Commit Graph

26907 Commits

Author SHA1 Message Date
Linus Torvalds
32627645e9 Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull key subsystem fixes from James Morris:
 "Here are a bunch of fixes for Linux keyrings, including:

   - Fix up the refcount handling now that key structs use the
     refcount_t type and the refcount_t ops don't allow a 0->1
     transition.

   - Fix a potential NULL deref after error in x509_cert_parse().

   - Don't put data for the crypto algorithms to use on the stack.

   - Fix the handling of a null payload being passed to add_key().

   - Fix incorrect cleanup an uninitialised key_preparsed_payload in
     key_update().

   - Explicit sanitisation of potentially secure data before freeing.

   - Fixes for the Diffie-Helman code"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (23 commits)
  KEYS: fix refcount_inc() on zero
  KEYS: Convert KEYCTL_DH_COMPUTE to use the crypto KPP API
  crypto : asymmetric_keys : verify_pefile:zero memory content before freeing
  KEYS: DH: add __user annotations to keyctl_kdf_params
  KEYS: DH: ensure the KDF counter is properly aligned
  KEYS: DH: don't feed uninitialized "otherinfo" into KDF
  KEYS: DH: forbid using digest_null as the KDF hash
  KEYS: sanitize key structs before freeing
  KEYS: trusted: sanitize all key material
  KEYS: encrypted: sanitize all key material
  KEYS: user_defined: sanitize key payloads
  KEYS: sanitize add_key() and keyctl() key payloads
  KEYS: fix freeing uninitialized memory in key_update()
  KEYS: fix dereferencing NULL payload with nonzero length
  KEYS: encrypted: use constant-time HMAC comparison
  KEYS: encrypted: fix race causing incorrect HMAC calculations
  KEYS: encrypted: fix buffer overread in valid_master_desc()
  KEYS: encrypted: avoid encrypting/decrypting stack buffers
  KEYS: put keyring if install_session_keyring_to_cred() fails
  KEYS: Delete an error message for a failed memory allocation in get_derived_key()
  ...
2017-06-11 16:17:29 -07:00
Linus Torvalds
9d0eb46246 Bug fixes (ARM, s390, x86)
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "Bug fixes (ARM, s390, x86)"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: async_pf: avoid async pf injection when in guest mode
  KVM: cpuid: Fix read/write out-of-bounds vulnerability in cpuid emulation
  arm: KVM: Allow unaligned accesses at HYP
  arm64: KVM: Allow unaligned accesses at EL2
  arm64: KVM: Preserve RES1 bits in SCTLR_EL2
  KVM: arm/arm64: Handle possible NULL stage2 pud when ageing pages
  KVM: nVMX: Fix exception injection
  kvm: async_pf: fix rcu_irq_enter() with irqs enabled
  KVM: arm/arm64: vgic-v3: Fix nr_pre_bits bitfield extraction
  KVM: s390: fix ais handling vs cpu model
  KVM: arm/arm64: Fix isues with GICv2 on GICv3 migration
2017-06-11 11:07:25 -07:00
Wanpeng Li
9bc1f09f6f KVM: async_pf: avoid async pf injection when in guest mode
INFO: task gnome-terminal-:1734 blocked for more than 120 seconds.
       Not tainted 4.12.0-rc4+ #8
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 gnome-terminal- D    0  1734   1015 0x00000000
 Call Trace:
  __schedule+0x3cd/0xb30
  schedule+0x40/0x90
  kvm_async_pf_task_wait+0x1cc/0x270
  ? __vfs_read+0x37/0x150
  ? prepare_to_swait+0x22/0x70
  do_async_page_fault+0x77/0xb0
  ? do_async_page_fault+0x77/0xb0
  async_page_fault+0x28/0x30

This is triggered by running both win7 and win2016 on L1 KVM simultaneously,
and then gives stress to memory on L1, I can observed this hang on L1 when
at least ~70% swap area is occupied on L0.

This is due to async pf was injected to L2 which should be injected to L1,
L2 guest starts receiving pagefault w/ bogus %cr2(apf token from the host
actually), and L1 guest starts accumulating tasks stuck in D state in
kvm_async_pf_task_wait() since missing PAGE_READY async_pfs.

This patch fixes the hang by doing async pf when executing L1 guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-11 08:39:24 +02:00
Bilal Amarni
47b2c3fff4 security/keys: add CONFIG_KEYS_COMPAT to Kconfig
CONFIG_KEYS_COMPAT is defined in arch-specific Kconfigs and is missing for
several 64-bit architectures : mips, parisc, tile.

At the moment and for those architectures, calling in 32-bit userspace the
keyctl syscall would return an ENOSYS error.

This patch moves the CONFIG_KEYS_COMPAT option to security/keys/Kconfig, to
make sure the compatibility wrapper is registered by default for any 64-bit
architecture as long as it is configured with CONFIG_COMPAT.

[DH: Modified to remove arm64 compat enablement also as requested by Eric
 Biggers]

Signed-off-by: Bilal Amarni <bilal.amarni@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
cc: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-06-09 13:29:45 +10:00
Wanpeng Li
a3641631d1 KVM: cpuid: Fix read/write out-of-bounds vulnerability in cpuid emulation
If "i" is the last element in the vcpu->arch.cpuid_entries[] array, it
potentially can be exploited the vulnerability. this will out-of-bounds
read and write.  Luckily, the effect is small:

	/* when no next entry is found, the current entry[i] is reselected */
	for (j = i + 1; ; j = (j + 1) % nent) {
		struct kvm_cpuid_entry2 *ej = &vcpu->arch.cpuid_entries[j];
		if (ej->function == e->function) {

It reads ej->maxphyaddr, which is user controlled.  However...

			ej->flags |= KVM_CPUID_FLAG_STATE_READ_NEXT;

After cpuid_entries there is

	int maxphyaddr;
	struct x86_emulate_ctxt emulate_ctxt;  /* 16-byte aligned */

So we have:

- cpuid_entries at offset 1B50 (6992)
- maxphyaddr at offset 27D0 (6992 + 3200 = 10192)
- padding at 27D4...27DF
- emulate_ctxt at 27E0

And it writes in the padding.  Pfew, writing the ops field of emulate_ctxt
would have been much worse.

This patch fixes it by modding the index to avoid the out-of-bounds
access. Worst case, i == j and ej->function == e->function,
the loop can bail out.

Reported-by: Moguofang <moguofang@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Guofang Mo <moguofang@huawei.com>
Cc: stable@vger.kernel.org
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-08 15:38:21 +02:00
Dominik Brodowski
5b0bc9ac2c x86/microcode/intel: Clear patch pointer before jettisoning the initrd
During early boot, load_ucode_intel_ap() uses __load_ucode_intel()
to obtain a pointer to the relevant microcode patch (embedded in the
initrd), and stores this value in 'intel_ucode_patch' to speed up the
microcode patch application for subsequent CPUs.

On resuming from suspend-to-RAM, however, load_ucode_ap() calls
load_ucode_intel_ap() for each non-boot-CPU. By then the initramfs is
long gone so the pointer stored in 'intel_ucode_patch' no longer points to
a valid microcode patch.

Clear that pointer so that we effectively fall back to the CPU hotplug
notifier callbacks to update the microcode.

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
[ Edit and massage commit message. ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org> # 4.10..
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170607095819.9754-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-08 10:03:05 +02:00
Wanpeng Li
d4912215d1 KVM: nVMX: Fix exception injection
WARNING: CPU: 3 PID: 2840 at arch/x86/kvm/vmx.c:10966 nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel]
 CPU: 3 PID: 2840 Comm: qemu-system-x86 Tainted: G           OE   4.12.0-rc3+ #23
 RIP: 0010:nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel]
 Call Trace:
  ? kvm_check_async_pf_completion+0xef/0x120 [kvm]
  ? rcu_read_lock_sched_held+0x79/0x80
  vmx_queue_exception+0x104/0x160 [kvm_intel]
  ? vmx_queue_exception+0x104/0x160 [kvm_intel]
  kvm_arch_vcpu_ioctl_run+0x1171/0x1ce0 [kvm]
  ? kvm_arch_vcpu_load+0x47/0x240 [kvm]
  ? kvm_arch_vcpu_load+0x62/0x240 [kvm]
  kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? __fget+0xf3/0x210
  do_vfs_ioctl+0xa4/0x700
  ? __fget+0x114/0x210
  SyS_ioctl+0x79/0x90
  do_syscall_64+0x81/0x220
  entry_SYSCALL64_slow_path+0x25/0x25

This is triggered occasionally by running both win7 and win2016 in L2, in
addition, EPT is disabled on both L1 and L2. It can't be reproduced easily.

Commit 0b6ac343fc (KVM: nVMX: Correct handling of exception injection) mentioned
that "KVM wants to inject page-faults which it got to the guest. This function
assumes it is called with the exit reason in vmcs02 being a #PF exception".
Commit e011c663 (KVM: nVMX: Check all exceptions for intercept during delivery to
L2) allows to check all exceptions for intercept during delivery to L2. However,
there is no guarantee the exit reason is exception currently, when there is an
external interrupt occurred on host, maybe a time interrupt for host which should
not be injected to guest, and somewhere queues an exception, then the function
nested_vmx_check_exception() will be called and the vmexit emulation codes will
try to emulate the "Acknowledge interrupt on exit" behavior, the warning is
triggered.

Reusing the exit reason from the L2->L0 vmexit is wrong in this case,
the reason must always be EXCEPTION_NMI when injecting an exception into
L1 as a nested vmexit.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Fixes: e011c663b9 ("KVM: nVMX: Check all exceptions for intercept during delivery to L2")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-06-06 15:21:50 +02:00
Paolo Bonzini
bbaf0e2b1c kvm: async_pf: fix rcu_irq_enter() with irqs enabled
native_safe_halt enables interrupts, and you just shouldn't
call rcu_irq_enter() with interrupts enabled.  Reorder the
call with the following local_irq_disable() to respect the
invariant.

Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-06-06 14:43:16 +02:00
Christian Sünkenberg
ae1d557d8f x86/cpu/cyrix: Add alternative Device ID of Geode GX1 SoC
A SoC variant of Geode GX1, notably NSC branded SC1100, seems to
report an inverted Device ID in its DIR0 configuration register,
specifically 0xb instead of the expected 0x4.

Catch this presumably quirky version so it's properly recognized
as GX1 and has its cache switched to write-back mode, which provides
a significant performance boost in most workloads.

SC1100's datasheet "Geode™ SC1100 Information Appliance On a Chip",
states in section 1.1.7.1 "Device ID" that device identification
values are specified in SC1100's device errata. These, however,
seem to not have been publicly released.

Wading through a number of boot logs and /proc/cpuinfo dumps found on
pastebin and blogs, this patch should mostly be relevant for a number
of now admittedly aging Soekris NET4801 and PC Engines WRAP devices,
the latter being the platform this issue was discovered on.
Performance impact was verified using "openssl speed", with
write-back caching scaling throughput between -3% and +41%.

Signed-off-by: Christian Sünkenberg <christian.suenkenberg@student.kit.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1496596719.26725.14.camel@student.kit.edu
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-05 08:34:20 +02:00
Linus Torvalds
f2a025defd Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Ingo Molnar:
 "Misc fixes:

   - revert a broken PAT commit that broke a number of systems

   - fix two preemptability warnings/bugs that can trigger under certain
     circumstances, in the debug code and in the microcode loader"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Revert "x86/PAT: Fix Xorg regression on CPUs that don't support PAT"
  x86/debug/32: Convert a smp_processor_id() call to raw to avoid DEBUG_PREEMPT warning
  x86/microcode/AMD: Change load_microcode_amd()'s param to bool to fix preemptibility bug
2017-06-02 08:53:42 -07:00
Linus Torvalds
f56f88ee3f Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull EFI fixes from Ingo Molnar:
 "Misc fixes:

   - three boot crash fixes for uncommon configurations

   - silence a boot warning under virtualization

   - plus a GCC 7 related (harmless) build warning fix"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/bgrt: Skip efi_bgrt_init() in case of non-EFI boot
  x86/efi: Correct EFI identity mapping under 'efi=old_map' when KASLR is enabled
  x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
  efi: Remove duplicate 'const' specifiers
  efi: Don't issue error message when booted under Xen
2017-06-02 08:51:53 -07:00
Linus Torvalds
9ea15a59c3 Many small x86 bug fixes: SVM segment registers access rights, nested VMX,
preempt notifiers, LAPIC virtual wire mode, NMI injection.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Paolo Bonzini:
 "Many small x86 bug fixes: SVM segment registers access rights, nested
  VMX, preempt notifiers, LAPIC virtual wire mode, NMI injection"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Fix nmi injection failure when vcpu got blocked
  KVM: SVM: do not zero out segment attributes if segment is unusable or not present
  KVM: SVM: ignore type when setting segment registers
  KVM: nVMX: fix nested_vmx_check_vmptr failure paths under debugging
  KVM: x86: Fix virtual wire mode
  KVM: nVMX: Fix handling of lmsw instruction
  KVM: X86: Fix preempt the preemption timer cancel
2017-06-01 10:48:09 -07:00
Ingo Molnar
c08d517480 Revert "x86/PAT: Fix Xorg regression on CPUs that don't support PAT"
This reverts commit cbed27cdf0.

As Andy Lutomirski observed:

 "I think this patch is bogus. pat_enabled() sure looks like it's
  supposed to return true if PAT is *enabled*, and these days PAT is
  'enabled' even if there's no HW PAT support."

Reported-by: Bernhard Held <berny156@gmx.de>
Reported-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Andy Lutomirski <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: stable@vger.kernel.org # v4.2+
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-06-01 15:52:23 +02:00
ZhuangYanying
47a66eed99 KVM: x86: Fix nmi injection failure when vcpu got blocked
When spin_lock_irqsave() deadlock occurs inside the guest, vcpu threads,
other than the lock-holding one, would enter into S state because of
pvspinlock. Then inject NMI via libvirt API "inject-nmi", the NMI could
not be injected into vm.

The reason is:
1 It sets nmi_queued to 1 when calling ioctl KVM_NMI in qemu, and sets
cpu->kvm_vcpu_dirty to true in do_inject_external_nmi() meanwhile.
2 It sets nmi_queued to 0 in process_nmi(), before entering guest, because
cpu->kvm_vcpu_dirty is true.

It's not enough just to check nmi_queued to decide whether to stay in
vcpu_block() or not. NMI should be injected immediately at any situation.
Add checking nmi_pending, and testing KVM_REQ_NMI replaces nmi_queued
in vm_vcpu_has_events().

Do the same change for SMIs.

Signed-off-by: Zhuang Yanying <ann.zhuangyanying@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-01 11:23:10 +02:00
Roman Pen
d9c1b5431d KVM: SVM: do not zero out segment attributes if segment is unusable or not present
This is a fix for the problem [1], where VMCB.CPL was set to 0 and interrupt
was taken on userspace stack.  The root cause lies in the specific AMD CPU
behaviour which manifests itself as unusable segment attributes on SYSRET.
The corresponding work around for the kernel is the following:

61f01dd941 ("x86_64, asm: Work around AMD SYSRET SS descriptor attribute issue")

In other turn virtualization side treated unusable segment incorrectly and
restored CPL from SS attributes, which were zeroed out few lines above.

In current patch it is assured only that P bit is cleared in VMCB.save state
and segment attributes are not zeroed out if segment is not presented or is
unusable, therefore CPL can be safely restored from DPL field.

This is only one part of the fix, since QEMU side should be fixed accordingly
not to zero out attributes on its side.  Corresponding patch will follow.

[1] Message id: CAJrWOzD6Xq==b-zYCDdFLgSRMPM-NkNuTSDFEtX=7MreT45i7Q@mail.gmail.com

Signed-off-by: Roman Pen <roman.penyaev@profitbricks.com>
Signed-off-by: Mikhail Sennikovskii <mikhail.sennikovskii@profitbricks.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim KrÄmář <rkrcmar@redhat.com>
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-06-01 11:21:17 +02:00
Gioh Kim
8eae9570d1 KVM: SVM: ignore type when setting segment registers
Commit 19bca6ab75 ("KVM: SVM: Fix cross vendor migration issue with
unusable bit") added checking type when setting unusable.
So unusable can be set if present is 0 OR type is 0.
According to the AMD processor manual, long mode ignores the type value
in segment descriptor. And type can be 0 if it is read-only data segment.
Therefore type value is not related to unusable flag.

This patch is based on linux-next v4.12.0-rc3.

Signed-off-by: Gioh Kim <gi-oh.kim@profitbricks.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-30 17:17:22 +02:00
Radim Krčmář
cbf712792b KVM: nVMX: fix nested_vmx_check_vmptr failure paths under debugging
kvm_skip_emulated_instruction() will return 0 if userspace is
single-stepping the guest.

kvm_skip_emulated_instruction() uses return status convention of exit
handler: 0 means "exit to userspace" and 1 means "continue vm entries".
The problem is that nested_vmx_check_vmptr() return status means
something else: 0 is ok, 1 is error.

This means we would continue executing after a failure.  Static checker
noticed it because vmptr was not initialized.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 6affcbedca ("KVM: x86: Add kvm_skip_emulated_instruction and use it.")
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-30 17:17:21 +02:00
Borislav Petkov
5d9070b1f0 x86/debug/32: Convert a smp_processor_id() call to raw to avoid DEBUG_PREEMPT warning
... to raw_smp_processor_id() to not trip the

  BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1

check. The reasoning behind it is that __warn() already uses the raw_
variants but the show_regs() path on 32-bit doesn't.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170528092212.fiod7kygpjm23m3o@pd.tnic
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-29 08:22:49 +02:00
Borislav Petkov
dac6ca243c x86/microcode/AMD: Change load_microcode_amd()'s param to bool to fix preemptibility bug
With CONFIG_DEBUG_PREEMPT enabled, I get:

  BUG: using smp_processor_id() in preemptible [00000000] code: swapper/0/1
  caller is debug_smp_processor_id
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.12.0-rc2+ #2
  Call Trace:
   dump_stack
   check_preemption_disabled
   debug_smp_processor_id
   save_microcode_in_initrd_amd
   ? microcode_init
   save_microcode_in_initrd
   ...

because, well, it says it above, we're using smp_processor_id() in
preemptible code.

But passing the CPU number is not really needed. It is only used to
determine whether we're on the BSP, and, if so, to save the microcode
patch for early loading.

 [ We don't absolutely need to do it on the BSP but we do that
   customarily there. ]

Instead, convert that function parameter to a boolean which denotes
whether the patch should be saved or not, thereby avoiding the use of
smp_processor_id() in preemptible code.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20170528200414.31305-1-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-29 08:22:48 +02:00
Baoquan He
94133e46a0 x86/efi: Correct EFI identity mapping under 'efi=old_map' when KASLR is enabled
For EFI with the 'efi=old_map' kernel option specified, the kernel will panic
when KASLR is enabled:

  BUG: unable to handle kernel paging request at 000000007febd57e
  IP: 0x7febd57e
  PGD 1025a067
  PUD 0

  Oops: 0010 [#1] SMP
  Call Trace:
   efi_enter_virtual_mode()
   start_kernel()
   x86_64_start_reservations()
   x86_64_start_kernel()
   start_cpu()

The root cause is that the identity mapping is not built correctly
in the 'efi=old_map' case.

On 'nokaslr' kernels, PAGE_OFFSET is 0xffff880000000000 which is PGDIR_SIZE
aligned. We can borrow the PUD table from the direct mappings safely. Given a
physical address X, we have pud_index(X) == pud_index(__va(X)).

However, on KASLR kernels, PAGE_OFFSET is PUD_SIZE aligned. For a given physical
address X, pud_index(X) != pud_index(__va(X)). We can't just copy the PGD entry
from direct mapping to build identity mapping, instead we need to copy the
PUD entries one by one from the direct mapping.

Fix it.

Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Bhupesh Sharma <bhsharma@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Young <dyoung@redhat.com>
Cc: Frank Ramsay <frank.ramsay@hpe.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Russ Anderson <rja@sgi.com>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170526113652.21339-5-matt@codeblueprint.co.uk
[ Fixed and reworded the changelog and code comments to be more readable. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-28 11:06:16 +02:00
Sai Praneeth
4e52797d2e x86/efi: Disable runtime services on kexec kernel if booted with efi=old_map
Booting kexec kernel with "efi=old_map" in kernel command line hits
kernel panic as shown below.

 BUG: unable to handle kernel paging request at ffff88007fe78070
 IP: virt_efi_set_variable.part.7+0x63/0x1b0
 PGD 7ea28067
 PUD 7ea2b067
 PMD 7ea2d067
 PTE 0
 [...]
 Call Trace:
  virt_efi_set_variable()
  efi_delete_dummy_variable()
  efi_enter_virtual_mode()
  start_kernel()
  x86_64_start_reservations()
  x86_64_start_kernel()
  start_cpu()

[ efi=old_map was never intended to work with kexec. The problem with
  using efi=old_map is that the virtual addresses are assigned from the
  memory region used by other kernel mappings; vmalloc() space.
  Potentially there could be collisions when booting kexec if something
  else is mapped at the virtual address we allocated for runtime service
  regions in the initial boot - Matt Fleming ]

Since kexec was never intended to work with efi=old_map, disable
runtime services in kexec if booted with efi=old_map, so that we don't
panic.

Tested-by: Lee Chun-Yi <jlee@suse.com>
Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Acked-by: Dave Young <dyoung@redhat.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Shankar <ravi.v.shankar@intel.com>
Cc: Ricardo Neri <ricardo.neri@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170526113652.21339-4-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-28 11:06:16 +02:00
Juergen Gross
1ea34adb87 efi: Don't issue error message when booted under Xen
When booted as Xen dom0 there won't be an EFI memmap allocated. Avoid
issuing an error message in this case:

  [    0.144079] efi: Failed to allocate new EFI memmap

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Cc: <stable@vger.kernel.org> # v4.9+
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170526113652.21339-2-matt@codeblueprint.co.uk
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-28 11:06:16 +02:00
Linus Torvalds
38e6bf238d Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fixes from Thomas Gleixner:
 "A series of fixes for X86:

   - The final fix for the end-of-stack issue in the unwinder
   - Handle non PAT systems gracefully
   - Prevent access to uninitiliazed memory
   - Move early delay calaibration after basic init
   - Fix Kconfig help text
   - Fix a cross compile issue
   - Unbreak older make versions"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/timers: Move simple_udelay_calibration past init_hypervisor_platform
  x86/alternatives: Prevent uninitialized stack byte read in apply_alternatives()
  x86/PAT: Fix Xorg regression on CPUs that don't support PAT
  x86/watchdog: Fix Kconfig help text file path reference to lockup watchdog documentation
  x86/build: Permit building with old make versions
  x86/unwind: Add end-of-stack check for ftrace handlers
  Revert "x86/entry: Fix the end of the stack for newly forked tasks"
  x86/boot: Use CROSS_COMPILE prefix for readelf
2017-05-27 09:17:58 -07:00
Linus Torvalds
de0b9d751b Merge branch 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RAS fixes from Thomas Gleixner:
 "Two fixlets for RAS:

   - Export memory_error() so the NFIT module can utilize it

   - Handle memory errors in NFIT correctly"

* 'ras-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  acpi, nfit: Fix the memory error check in nfit_handle_mce()
  x86/MCE: Export memory_error()
2017-05-27 09:06:43 -07:00
Thomas Gleixner
6ee98ffeea x86/ftrace: Make sure that ftrace trampolines are not RWX
ftrace use module_alloc() to allocate trampoline pages. The mapping of
module_alloc() is RWX, which makes sense as the memory is written to right
after allocation. But nothing makes these pages RO after writing to them.

Add proper set_memory_rw/ro() calls to protect the trampolines after
modification.

Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1705251056410.1862@nanos

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-05-26 22:37:02 -04:00
Steven Rostedt (VMware)
a53276e282 x86/mm/ftrace: Do not bug in early boot on irqs_disabled in cpu_flush_range()
With function tracing starting in early bootup and having its trampoline
pages being read only, a bug triggered with the following:

kernel BUG at arch/x86/mm/pageattr.c:189!
invalid opcode: 0000 [#1] SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 4.12.0-rc2-test+ #3
Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014
task: ffffffffb4222500 task.stack: ffffffffb4200000
RIP: 0010:change_page_attr_set_clr+0x269/0x302
RSP: 0000:ffffffffb4203c88 EFLAGS: 00010046
RAX: 0000000000000046 RBX: 0000000000000000 RCX: 00000001b6000000
RDX: ffffffffb4203d40 RSI: 0000000000000000 RDI: ffffffffb4240d60
RBP: ffffffffb4203d18 R08: 00000001b6000000 R09: 0000000000000001
R10: ffffffffb4203aa8 R11: 0000000000000003 R12: ffffffffc029b000
R13: ffffffffb4203d40 R14: 0000000000000001 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff9a639ea00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff9a636b384000 CR3: 00000001ea21d000 CR4: 00000000000406b0
Call Trace:
 change_page_attr_clear+0x1f/0x21
 set_memory_ro+0x1e/0x20
 arch_ftrace_update_trampoline+0x207/0x21c
 ? ftrace_caller+0x64/0x64
 ? 0xffffffffc029b000
 ftrace_startup+0xf4/0x198
 register_ftrace_function+0x26/0x3c
 function_trace_init+0x5e/0x73
 tracer_init+0x1e/0x23
 tracing_set_tracer+0x127/0x15a
 register_tracer+0x19b/0x1bc
 init_function_trace+0x90/0x92
 early_trace_init+0x236/0x2b3
 start_kernel+0x200/0x3f5
 x86_64_start_reservations+0x29/0x2b
 x86_64_start_kernel+0x17c/0x18f
 secondary_startup_64+0x9f/0x9f
 ? secondary_startup_64+0x9f/0x9f

Interrupts should not be enabled at this early in the boot process. It is
also fine to leave interrupts enabled during this time as there's only one
CPU running, and on_each_cpu() means to only run on the current CPU.

If early_boot_irqs_disabled is set, it is safe to run cpu_flush_range() with
interrupts disabled. Don't trigger a BUG_ON() in that case.

Link: http://lkml.kernel.org/r/20170526093717.0be3b849@gandalf.local.home
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-05-26 22:37:01 -04:00
Masami Hiramatsu
c93f5cf571 kprobes/x86: Fix to set RWX bits correctly before releasing trampoline
Fix kprobes to set(recover) RWX bits correctly on trampoline
buffer before releasing it. Releasing readonly page to
module_memfree() crash the kernel.

Without this fix, if kprobes user register a bunch of kprobes
in function body (since kprobes on function entry usually
use ftrace) and unregister it, kernel hits a BUG and crash.

Link: http://lkml.kernel.org/r/149570868652.3518.14120169373590420503.stgit@devbox

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Fixes: d0381c81c2 ("kprobes/x86: Set kprobes pages read-only")
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2017-05-26 22:37:00 -04:00
Jan H. Schönherr
52b5419016 KVM: x86: Fix virtual wire mode
Intel SDM says, that at most one LAPIC should be configured with ExtINT
delivery. KVM configures all LAPICs this way. This causes pic_unlock()
to kick the first available vCPU from the internal KVM data structures.
If this vCPU is not the BSP, but some not-yet-booted AP, the BSP may
never realize that there is an interrupt.

Fix that by enabling ExtINT delivery only for the BSP.

This allows booting a Linux guest without a TSC in the above situation.
Otherwise the BSP gets stuck in calibrate_delay_converge().

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-26 18:01:21 +02:00
Jan H. Schönherr
e1d39b17e0 KVM: nVMX: Fix handling of lmsw instruction
The decision whether or not to exit from L2 to L1 on an lmsw instruction is
based on bogus values: instead of using the information encoded within the
exit qualification, it uses the data also used for the mov-to-cr
instruction, which boils down to using whatever is in %eax at that point.

Use the correct values instead.

Without this fix, an L1 may not get notified when a 32-bit Linux L2
switches its secondary CPUs to protected mode; the L1 is only notified on
the next modification of CR0. This short time window poses a problem, when
there is some other reason to exit to L1 in between. Then, L2 will be
resumed in real mode and chaos ensues.

Signed-off-by: Jan H. Schönherr <jschoenh@amazon.de>
Reviewed-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-26 17:59:27 +02:00
Wanpeng Li
5acc1ca4fb KVM: X86: Fix preempt the preemption timer cancel
Preemption can occur during cancel preemption timer, and there will be
inconsistent status in lapic, vmx and vmcs field.

          CPU0                    CPU1

  preemption timer vmexit
  handle_preemption_timer(vCPU0)
    kvm_lapic_expired_hv_timer
      vmx_cancel_hv_timer
        vmx->hv_deadline_tsc = -1
        vmcs_clear_bits
        /* hv_timer_in_use still true */
  sched_out
                           sched_in
                           kvm_arch_vcpu_load
                             vmx_set_hv_timer
                               write vmx->hv_deadline_tsc
                               vmcs_set_bits
                           /* back in kvm_lapic_expired_hv_timer */
                           hv_timer_in_use = false
                           ...
                           vmx_vcpu_run
                             vmx_arm_hv_run
                               write preemption timer deadline
                             spurious preemption timer vmexit
                               handle_preemption_timer(vCPU0)
                                 kvm_lapic_expired_hv_timer
                                   WARN_ON(!apic->lapic_timer.hv_timer_in_use);

This can be reproduced sporadically during boot of L2 on a
preemptible L1, causing a splat on L1.

 WARNING: CPU: 3 PID: 1952 at arch/x86/kvm/lapic.c:1529 kvm_lapic_expired_hv_timer+0xb5/0xd0 [kvm]
 CPU: 3 PID: 1952 Comm: qemu-system-x86 Not tainted 4.12.0-rc1+ #24 RIP: 0010:kvm_lapic_expired_hv_timer+0xb5/0xd0 [kvm]
  Call Trace:
  handle_preemption_timer+0xe/0x20 [kvm_intel]
  vmx_handle_exit+0xc9/0x15f0 [kvm_intel]
  ? lock_acquire+0xdb/0x250
  ? lock_acquire+0xdb/0x250
  ? kvm_arch_vcpu_ioctl_run+0xdf3/0x1ce0 [kvm]
  kvm_arch_vcpu_ioctl_run+0xe55/0x1ce0 [kvm]
  kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? __fget+0xf3/0x210
  do_vfs_ioctl+0xa4/0x700
  ? __fget+0x114/0x210
  SyS_ioctl+0x79/0x90
  do_syscall_64+0x8f/0x750
  ? trace_hardirqs_on_thunk+0x1a/0x1c
  entry_SYSCALL64_slow_path+0x25/0x25

This patch fixes it by disabling preemption while cancelling
preemption timer.  This way cancel_hv_timer is atomic with
respect to kvm_arch_vcpu_load.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-05-26 17:46:20 +02:00
Jan Kiszka
702644ec1c x86/timers: Move simple_udelay_calibration past init_hypervisor_platform
This ensures that adjustments to x86_platform done by the hypervisor
setup is already respected by this simple calibration.

The current user of this, introduced by 1b5aeebf3a ("x86/earlyprintk:
Add support for earlyprintk via USB3 debug port"), comes much later
into play.

Fixes: dd759d93f4 ("x86/timers: Add simple udelay calibration")
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: http://lkml.kernel.org/r/5e89fe60-aab3-2c1c-aba8-32f8ad376189@siemens.com
2017-05-26 13:04:09 +02:00
Mateusz Jurczyk
fc152d22d6 x86/alternatives: Prevent uninitialized stack byte read in apply_alternatives()
In the current form of the code, if a->replacementlen is 0, the reference
to *insnbuf for comparison touches potentially garbage memory. While it
doesn't affect the execution flow due to the subsequent a->replacementlen
comparison, it is (rightly) detected as use of uninitialized memory by a
runtime instrumentation currently under my development, and could be
detected as such by other tools in the future, too (e.g. KMSAN).

Fix the "false-positive" by reordering the conditions to first check the
replacement instruction length before referencing specific opcode bytes.

Signed-off-by: Mateusz Jurczyk <mjurczyk@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Cc: Andy Lutomirski <luto@kernel.org>
Link: http://lkml.kernel.org/r/20170524135500.27223-1-mjurczyk@google.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-05-24 16:18:12 +02:00
Mikulas Patocka
cbed27cdf0 x86/PAT: Fix Xorg regression on CPUs that don't support PAT
In the file arch/x86/mm/pat.c, there's a '__pat_enabled' variable. The
variable is set to 1 by default and the function pat_init() sets
__pat_enabled to 0 if the CPU doesn't support PAT.

However, on AMD K6-3 CPUs, the processor initialization code never calls
pat_init() and so __pat_enabled stays 1 and the function pat_enabled()
returns true, even though the K6-3 CPU doesn't support PAT.

The result of this bug is that a kernel warning is produced when attempting to
start the Xserver and the Xserver doesn't start (fork() returns ENOMEM).
Another symptom of this bug is that the framebuffer driver doesn't set the
K6-3 MTRR registers:

  x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 3891 at arch/x86/mm/pat.c:1020 untrack_pfn+0x5c/0x9f
  ...
  x86/PAT: Xorg:3891 map pfn expected mapping type uncached-minus for [mem 0xe4000000-0xe5ffffff], got write-combining

To fix the bug change pat_enabled() so that it returns true only if PAT
initialization was actually done.

Also, I changed boot_cpu_has(X86_FEATURE_PAT) to
this_cpu_has(X86_FEATURE_PAT) in pat_ap_init(), so that we check the PAT
feature on the processor that is being initialized.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: stable@vger.kernel.org # v4.2+
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1704181501450.26399@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 10:17:23 +02:00
Benjamin Peterson
c9525a3fab x86/watchdog: Fix Kconfig help text file path reference to lockup watchdog documentation
Signed-off-by: Benjamin Peterson <bp@benjamin.pe>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Fixes: 9919cba7ff ("watchdog: Update documentation")
Link: http://lkml.kernel.org/r/20170521002016.13258-1-bp@benjamin.pe
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 09:06:32 +02:00
Jan Kiszka
7e6091209f x86/build: Permit building with old make versions
At least Make 3.82 dislikes the tab in front of the $(warning) function:

  arch/x86/Makefile:162: *** recipe commences before first target.  Stop.

Let's be gentle.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1944fcd8-e3df-d1f7-c0e4-60aeb1917a24@siemens.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 09:05:17 +02:00
Josh Poimboeuf
519fb5c335 x86/unwind: Add end-of-stack check for ftrace handlers
Dave Jones and Steven Rostedt reported unwinder warnings like the
following:

  WARNING: kernel stack frame pointer at ffff8800bda0ff30 in sshd:1090 has bad value 000055b32abf1fa8

In both cases, the unwinder was attempting to unwind from an ftrace
handler into entry code.  The callchain was something like:

  syscall entry code
    C function
      ftrace handler
        save_stack_trace()

The problem is that the unwinder's end-of-stack logic gets confused by
the way ftrace lays out the stack frame (with fentry enabled).

I was able to recreate this warning with:

  echo call_usermodehelper_exec_async:stacktrace > /sys/kernel/debug/tracing/set_ftrace_filter
  (exit login session)

I considered fixing this by changing the ftrace code to rewrite the
stack to make the unwinder happy.  But that seemed too intrusive after I
implemented it.  Instead, just add another check to the unwinder's
end-of-stack logic to detect this special case.

Side note: We could probably get rid of these end-of-stack checks by
encoding the frame pointer for syscall entry just like we do for
interrupt entry.  That would be simpler, but it would also be a lot more
intrusive since it would slightly affect the performance of every
syscall.

Reported-by: Dave Jones <davej@codemonkey.org.uk>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: live-patching@vger.kernel.org
Fixes: c32c47c68a ("x86/unwind: Warn on bad frame pointer")
Link: http://lkml.kernel.org/r/671ba22fbc0156b8f7e0cfa5ab2a795e08bc37e1.1495553739.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 09:05:16 +02:00
Josh Poimboeuf
ebd574994c Revert "x86/entry: Fix the end of the stack for newly forked tasks"
Petr Mladek reported the following warning when loading the livepatch
sample module:

  WARNING: CPU: 1 PID: 3699 at arch/x86/kernel/stacktrace.c:132 save_stack_trace_tsk_reliable+0x133/0x1a0
  ...
  Call Trace:
   __schedule+0x273/0x820
   schedule+0x36/0x80
   kthreadd+0x305/0x310
   ? kthread_create_on_cpu+0x80/0x80
   ? icmp_echo.part.32+0x50/0x50
   ret_from_fork+0x2c/0x40

That warning means the end of the stack is no longer recognized as such
for newly forked tasks.  The problem was introduced with the following
commit:

  ff3f7e2475 ("x86/entry: Fix the end of the stack for newly forked tasks")

... which was completely misguided.  It only partially fixed the
reported issue, and it introduced another bug in the process.  None of
the other entry code saves the frame pointer before calling into C code,
so it doesn't make sense for ret_from_fork to do so either.

Contrary to what I originally thought, the original issue wasn't related
to newly forked tasks.  It was actually related to ftrace.  When entry
code calls into a function which then calls into an ftrace handler, the
stack frame looks different than normal.

The original issue will be fixed in the unwinder, in a subsequent patch.

Reported-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Dave Jones <davej@codemonkey.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: live-patching@vger.kernel.org
Fixes: ff3f7e2475 ("x86/entry: Fix the end of the stack for newly forked tasks")
Link: http://lkml.kernel.org/r/f350760f7e82f0750c8d1dd093456eb212751caa.1495553739.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-05-24 09:05:16 +02:00
Linus Torvalds
33c9e97290 x86: fix 32-bit case of __get_user_asm_u64()
The code to fetch a 64-bit value from user space was entirely buggered,
and has been since the code was merged in early 2016 in commit
b2f680380d ("x86/mm/32: Add support for 64-bit __get_user() on 32-bit
kernels").

Happily the buggered routine is almost certainly entirely unused, since
the normal way to access user space memory is just with the non-inlined
"get_user()", and the inlined version didn't even historically exist.

The normal "get_user()" case is handled by external hand-written asm in
arch/x86/lib/getuser.S that doesn't have either of these issues.

There were two independent bugs in __get_user_asm_u64():

 - it still did the STAC/CLAC user space access marking, even though
   that is now done by the wrapper macros, see commit 11f1a4b975
   ("x86: reorganize SMAP handling in user space accesses").

   This didn't result in a semantic error, it just means that the
   inlined optimized version was hugely less efficient than the
   allegedly slower standard version, since the CLAC/STAC overhead is
   quite high on modern Intel CPU's.

 - the double register %eax/%edx was marked as an output, but the %eax
   part of it was touched early in the asm, and could thus clobber other
   inputs to the asm that gcc didn't expect it to touch.

   In particular, that meant that the generated code could look like
   this:

        mov    (%eax),%eax
        mov    0x4(%eax),%edx

   where the load of %edx obviously was _supposed_ to be from the 32-bit
   word that followed the source of %eax, but because %eax was
   overwritten by the first instruction, the source of %edx was
   basically random garbage.

The fixes are trivial: remove the extraneous STAC/CLAC entries, and mark
the 64-bit output as early-clobber to let gcc know that no inputs should
alias with the output register.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable@kernel.org   # v4.8+
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-21 18:26:54 -07:00
Linus Torvalds
334a023ee5 Clean up x86 unsafe_get/put_user() type handling
Al noticed that unsafe_put_user() had type problems, and fixed them in
commit a7cc722fff ("fix unsafe_put_user()"), which made me look more
at those functions.

It turns out that unsafe_get_user() had a type issue too: it limited the
largest size of the type it could handle to "unsigned long".  Which is
fine with the current users, but doesn't match our existing normal
get_user() semantics, which can also handle "u64" even when that does
not fit in a long.

While at it, also clean up the type cast in unsafe_put_user().  We
actually want to just make it an assignment to the expected type of the
pointer, because we actually do want warnings from types that don't
convert silently.  And it makes the code more readable by not having
that one very long and complex line.

[ This patch might become stable material if we ever end up back-porting
  any new users of the unsafe uaccess code, but as things stand now this
  doesn't matter for any current existing uses. ]

Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-21 15:25:46 -07:00
Borislav Petkov
2d1f406139 x86/MCE: Export memory_error()
Export the function which checks whether an MCE is a memory error to
other users so that we can reuse the logic. Drop the boot_cpu_data use,
while at it, as mce.cpuvendor already has the CPU vendor in there.

Integrate a piece from a patch from Vishal Verma
<vishal.l.verma@intel.com> to export it for modules (nfit).

The main reason we're exporting it is that the nfit handler
nfit_handle_mce() needs to detect a memory error properly before doing
its recovery actions.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/20170519093915.15413-2-bp@alien8.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-05-21 21:39:58 +02:00
Linus Torvalds
f3926e4c2a Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull misc uaccess fixes from Al Viro:
 "Fix for unsafe_put_user() (no callers currently in mainline, but
  anyone starting to use it will step into that) + alpha osf_wait4()
  infoleak fix"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  osf_wait4(): fix infoleak
  fix unsafe_put_user()
2017-05-21 12:06:44 -07:00
Al Viro
a7cc722fff fix unsafe_put_user()
__put_user_size() relies upon its first argument having the same type as what
the second one points to; the only other user makes sure of that and
unsafe_put_user() should do the same.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-05-21 13:09:57 -04:00
Rob Landley
3780578761 x86/boot: Use CROSS_COMPILE prefix for readelf
The boot code Makefile contains a straight 'readelf' invocation. This
causes build warnings in cross compile environments, when there is no
unprefixed readelf accessible via $PATH.

Add the missing $(CROSS_COMPILE) prefix.

[ tglx: Rewrote changelog ]

Fixes: 98f7852537 ("x86/boot: Refuse to build with data relocations")
Signed-off-by: Rob Landley <rob@landley.net>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Paul Bolle <pebolle@tiscali.nl>
Cc: "H.J. Lu" <hjl.tools@gmail.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/ced18878-693a-9576-a024-113ef39a22c0@landley.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2017-05-21 13:04:27 +02:00
Linus Torvalds
4217fdde34 KVM fixes for v4.12-rc2
ARM:
  - A fix for a build failure introduced in -rc1 when tracepoints are
    enabled on 32-bit ARM.
  - Disabling use of stack pointer protection in the hyp code which can
    cause panics.
  - A handful of VGIC fixes.
  - A fix to the init of the redistributors on GICv3 systems that
    prevented boot with kvmtool on GICv3 systems introduced in -rc1.
  - A number of race conditions fixed in our MMU handling code.
  - A fix for the guest being able to program the debug extensions for
    the host on the 32-bit side.
 
 PPC:
  - Fixes for build failures with PR KVM configurations.
  - A fix for a host crash that can occur on POWER9 with radix guests.
 
 x86:
  - Fixes for nested PML and nested EPT.
  - A fix for crashes caused by reserved bits in SSE MXCSR that could
    have been set by userspace.
  - An optimization of halt polling that fixes high CPU overhead.
  - Fixes for four reports from Dan Carpenter's static checker.
  - A protection around code that shouldn't have been preemptible.
  - A fix for port IO emulation.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull KVM fixes from Radim Krčmář:
 "ARM:
   - a fix for a build failure introduced in -rc1 when tracepoints are
     enabled on 32-bit ARM.

   - disable use of stack pointer protection in the hyp code which can
     cause panics.

   - a handful of VGIC fixes.

   - a fix to the init of the redistributors on GICv3 systems that
     prevented boot with kvmtool on GICv3 systems introduced in -rc1.

   - a number of race conditions fixed in our MMU handling code.

   - a fix for the guest being able to program the debug extensions for
     the host on the 32-bit side.

  PPC:
   - fixes for build failures with PR KVM configurations.

   - a fix for a host crash that can occur on POWER9 with radix guests.

  x86:
   - fixes for nested PML and nested EPT.

   - a fix for crashes caused by reserved bits in SSE MXCSR that could
     have been set by userspace.

   - an optimization of halt polling that fixes high CPU overhead.

   - fixes for four reports from Dan Carpenter's static checker.

   - a protection around code that shouldn't have been preemptible.

   - a fix for port IO emulation"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (27 commits)
  KVM: x86: prevent uninitialized variable warning in check_svme()
  KVM: x86/vPMU: fix undefined shift in intel_pmu_refresh()
  KVM: x86: zero base3 of unusable segments
  KVM: X86: Fix read out-of-bounds vulnerability in kvm pio emulation
  KVM: x86: Fix potential preemption when get the current kvmclock timestamp
  KVM: Silence underflow warning in avic_get_physical_id_entry()
  KVM: arm/arm64: Hold slots_lock when unregistering kvm io bus devices
  KVM: arm/arm64: Fix bug when registering redist iodevs
  KVM: x86: lower default for halt_poll_ns
  kvm: arm/arm64: Fix use after free of stage2 page table
  kvm: arm/arm64: Force reading uncached stage2 PGD
  KVM: nVMX: fix EPT permissions as reported in exit qualification
  KVM: VMX: Don't enable EPT A/D feature if EPT feature is disabled
  KVM: x86: Fix load damaged SSEx MXCSR register
  kvm: nVMX: off by one in vmx_write_pml_buffer()
  KVM: arm: rename pm_fake handler to trap_raz_wi
  KVM: arm: plug potential guest hardware debug leakage
  kvm: arm/arm64: Fix race in resetting stage2 PGD
  KVM: arm/arm64: vgic-v3: Use PREbits to infer the number of ICH_APxRn_EL2 registers
  KVM: arm/arm64: vgic-v3: Do not use Active+Pending state for a HW interrupt
  ...
2017-05-19 15:13:13 -07:00
Linus Torvalds
9e856e4b47 xen: fixes for 4.12 rc2
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Merge tag 'for-linus-4.12b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen fixes from Juergen Gross:
 "Some fixes for the new Xen 9pfs frontend and some minor cleanups"

* tag 'for-linus-4.12b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: make xen_flush_tlb_all() static
  xen: cleanup pvh leftovers from pv-only sources
  xen/9pfs: p9_trans_xen_init and p9_trans_xen_exit can be static
  xen/9pfs: fix return value check in xen_9pfs_front_probe()
2017-05-19 15:06:48 -07:00
Radim Krčmář
92ceb7679a KVM: x86: prevent uninitialized variable warning in check_svme()
get_msr() of MSR_EFER is currently always going to succeed, but static
checker doesn't see that far.

Don't complicate stuff and just use 0 for the fallback -- it means that
the feature is not present.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-19 19:59:28 +02:00
Radim Krčmář
34b0dadbdf KVM: x86/vPMU: fix undefined shift in intel_pmu_refresh()
Static analysis noticed that pmu->nr_arch_gp_counters can be 32
(INTEL_PMC_MAX_GENERIC) and therefore cannot be used to shift 'int'.

I didn't add BUILD_BUG_ON for it as we have a better checker.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 25462f7f52 ("KVM: x86/vPMU: Define kvm_pmu_ops to support vPMU function dispatch")
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-19 19:59:27 +02:00
Radim Krčmář
f0367ee1d6 KVM: x86: zero base3 of unusable segments
Static checker noticed that base3 could be used uninitialized if the
segment was not present (useable).  Random stack values probably would
not pass VMCS entry checks.

Reported-by:  Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 1aa366163b ("KVM: x86 emulator: consolidate segment accessors")
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-19 19:59:27 +02:00
Wanpeng Li
cbfc6c9184 KVM: X86: Fix read out-of-bounds vulnerability in kvm pio emulation
Huawei folks reported a read out-of-bounds vulnerability in kvm pio emulation.

- "inb" instruction to access PIT Mod/Command register (ioport 0x43, write only,
  a read should be ignored) in guest can get a random number.
- "rep insb" instruction to access PIT register port 0x43 can control memcpy()
  in emulator_pio_in_emulated() to copy max 0x400 bytes but only read 1 bytes,
  which will disclose the unimportant kernel memory in host but no crash.

The similar test program below can reproduce the read out-of-bounds vulnerability:

void hexdump(void *mem, unsigned int len)
{
        unsigned int i, j;

        for(i = 0; i < len + ((len % HEXDUMP_COLS) ? (HEXDUMP_COLS - len % HEXDUMP_COLS) : 0); i++)
        {
                /* print offset */
                if(i % HEXDUMP_COLS == 0)
                {
                        printf("0x%06x: ", i);
                }

                /* print hex data */
                if(i < len)
                {
                        printf("%02x ", 0xFF & ((char*)mem)[i]);
                }
                else /* end of block, just aligning for ASCII dump */
                {
                        printf("   ");
                }

                /* print ASCII dump */
                if(i % HEXDUMP_COLS == (HEXDUMP_COLS - 1))
                {
                        for(j = i - (HEXDUMP_COLS - 1); j <= i; j++)
                        {
                                if(j >= len) /* end of block, not really printing */
                                {
                                        putchar(' ');
                                }
                                else if(isprint(((char*)mem)[j])) /* printable char */
                                {
                                        putchar(0xFF & ((char*)mem)[j]);
                                }
                                else /* other char */
                                {
                                        putchar('.');
                                }
                        }
                        putchar('\n');
                }
        }
}

int main(void)
{
	int i;
	if (iopl(3))
	{
		err(1, "set iopl unsuccessfully\n");
		return -1;
	}
	static char buf[0x40];

	/* test ioport 0x40,0x41,0x42,0x43,0x44,0x45 */

	memset(buf, 0xab, sizeof(buf));

	asm volatile("push %rdi;");
	asm volatile("mov %0, %%rdi;"::"q"(buf));

	asm volatile ("mov $0x40, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("mov $0x41, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("mov $0x42, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("mov $0x43, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("mov $0x44, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("mov $0x45, %rdx;");
	asm volatile ("in %dx,%al;");
	asm volatile ("stosb;");

	asm volatile ("pop %rdi;");
	hexdump(buf, 0x40);

	printf("\n");

	/* ins port 0x40 */

	memset(buf, 0xab, sizeof(buf));

	asm volatile("push %rdi;");
	asm volatile("mov %0, %%rdi;"::"q"(buf));

	asm volatile ("mov $0x20, %rcx;");
	asm volatile ("mov $0x40, %rdx;");
	asm volatile ("rep insb;");

	asm volatile ("pop %rdi;");
	hexdump(buf, 0x40);

	printf("\n");

	/* ins port 0x43 */

	memset(buf, 0xab, sizeof(buf));

	asm volatile("push %rdi;");
	asm volatile("mov %0, %%rdi;"::"q"(buf));

	asm volatile ("mov $0x20, %rcx;");
	asm volatile ("mov $0x43, %rdx;");
	asm volatile ("rep insb;");

	asm volatile ("pop %rdi;");
	hexdump(buf, 0x40);

	printf("\n");
	return 0;
}

The vcpu->arch.pio_data buffer is used by both in/out instrutions emulation
w/o clear after using which results in some random datas are left over in
the buffer. Guest reads port 0x43 will be ignored since it is write only,
however, the function kernel_pio() can't distigush this ignore from successfully
reads data from device's ioport. There is no new data fill the buffer from
port 0x43, however, emulator_pio_in_emulated() will copy the stale data in
the buffer to the guest unconditionally. This patch fixes it by clearing the
buffer before in instruction emulation to avoid to grant guest the stale data
in the buffer.

In addition, string I/O is not supported for in kernel device. So there is no
iteration to read ioport %RCX times for string I/O. The function kernel_pio()
just reads one round, and then copy the io size * %RCX to the guest unconditionally,
actually it copies the one round ioport data w/ other random datas which are left
over in the vcpu->arch.pio_data buffer to the guest. This patch fixes it by
introducing the string I/O support for in kernel device in order to grant the right
ioport datas to the guest.

Before the patch:

0x000000: fe 38 93 93 ff ff ab ab .8......
0x000008: ab ab ab ab ab ab ab ab ........
0x000010: ab ab ab ab ab ab ab ab ........
0x000018: ab ab ab ab ab ab ab ab ........
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

0x000000: f6 00 00 00 00 00 00 00 ........
0x000008: 00 00 00 00 00 00 00 00 ........
0x000010: 00 00 00 00 4d 51 30 30 ....MQ00
0x000018: 30 30 20 33 20 20 20 20 00 3
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

0x000000: f6 00 00 00 00 00 00 00 ........
0x000008: 00 00 00 00 00 00 00 00 ........
0x000010: 00 00 00 00 4d 51 30 30 ....MQ00
0x000018: 30 30 20 33 20 20 20 20 00 3
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

After the patch:

0x000000: 1e 02 f8 00 ff ff ab ab ........
0x000008: ab ab ab ab ab ab ab ab ........
0x000010: ab ab ab ab ab ab ab ab ........
0x000018: ab ab ab ab ab ab ab ab ........
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

0x000000: d2 e2 d2 df d2 db d2 d7 ........
0x000008: d2 d3 d2 cf d2 cb d2 c7 ........
0x000010: d2 c4 d2 c0 d2 bc d2 b8 ........
0x000018: d2 b4 d2 b0 d2 ac d2 a8 ........
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

0x000000: 00 00 00 00 00 00 00 00 ........
0x000008: 00 00 00 00 00 00 00 00 ........
0x000010: 00 00 00 00 00 00 00 00 ........
0x000018: 00 00 00 00 00 00 00 00 ........
0x000020: ab ab ab ab ab ab ab ab ........
0x000028: ab ab ab ab ab ab ab ab ........
0x000030: ab ab ab ab ab ab ab ab ........
0x000038: ab ab ab ab ab ab ab ab ........

Reported-by: Moguofang <moguofang@huawei.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Moguofang <moguofang@huawei.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-19 19:59:26 +02:00
Wanpeng Li
e2c2206a18 KVM: x86: Fix potential preemption when get the current kvmclock timestamp
BUG: using __this_cpu_read() in preemptible [00000000] code: qemu-system-x86/2809
 caller is __this_cpu_preempt_check+0x13/0x20
 CPU: 2 PID: 2809 Comm: qemu-system-x86 Not tainted 4.11.0+ #13
 Call Trace:
  dump_stack+0x99/0xce
  check_preemption_disabled+0xf5/0x100
  __this_cpu_preempt_check+0x13/0x20
  get_kvmclock_ns+0x6f/0x110 [kvm]
  get_time_ref_counter+0x5d/0x80 [kvm]
  kvm_hv_process_stimers+0x2a1/0x8a0 [kvm]
  ? kvm_hv_process_stimers+0x2a1/0x8a0 [kvm]
  ? kvm_arch_vcpu_ioctl_run+0xac9/0x1ce0 [kvm]
  kvm_arch_vcpu_ioctl_run+0x5bf/0x1ce0 [kvm]
  kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm]
  ? __fget+0xf3/0x210
  do_vfs_ioctl+0xa4/0x700
  ? __fget+0x114/0x210
  SyS_ioctl+0x79/0x90
  entry_SYSCALL_64_fastpath+0x23/0xc2
 RIP: 0033:0x7f9d164ed357
  ? __this_cpu_preempt_check+0x13/0x20

This can be reproduced by run kvm-unit-tests/hyperv_stimer.flat w/
CONFIG_PREEMPT and CONFIG_DEBUG_PREEMPT enabled.

Safe access to per-CPU data requires a couple of constraints, though: the
thread working with the data cannot be preempted and it cannot be migrated
while it manipulates per-CPU variables. If the thread is preempted, the
thread that replaces it could try to work with the same variables; migration
to another CPU could also cause confusion. However there is no preemption
disable when reads host per-CPU tsc rate to calculate the current kvmclock
timestamp.

This patch fixes it by utilizing get_cpu/put_cpu pair to guarantee both
__this_cpu_read() and rdtsc() are not preempted.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
2017-05-19 19:59:25 +02:00