Commit e504c9098e (kvm, vmx: Fix lazy FPU on nested guest, 2013-11-13)
highlighted a real problem, but the fix was subtly wrong.
nested_read_cr0 is the CR0 as read by L2, but here we want to look at
the CR0 value reflecting L1's setup. In other words, L2 might think
that TS=0 (so nested_read_cr0 has the bit clear); but if L1 is actually
running it with TS=1, we should inject the fault into L1.
The effective value of CR0 in L2 is contained in vmcs12->guest_cr0, use
it.
Fixes: e504c9098e
Reported-by: Kashyap Chamarty <kchamart@redhat.com>
Reported-by: Stefan Bader <stefan.bader@canonical.com>
Tested-by: Kashyap Chamarty <kchamart@redhat.com>
Tested-by: Anthoine Bourgeois <bourgeois@bertin.fr>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The problem occurs when the guest performs a pusha with the stack
address pointing to an mmio address (or an invalid guest physical
address) to start with, but then extending into an ordinary guest
physical address. When doing repeated emulated pushes
emulator_read_write sets mmio_needed to 1 on the first one. On a
later push when the stack points to regular memory,
mmio_nr_fragments is set to 0, but mmio_is_needed is not set to 0.
As a result, KVM exits to userspace, and then returns to
complete_emulated_mmio. In complete_emulated_mmio
vcpu->mmio_cur_fragment is incremented. The termination condition of
vcpu->mmio_cur_fragment == vcpu->mmio_nr_fragments is never achieved.
The code bounces back and fourth to userspace incrementing
mmio_cur_fragment past it's buffer. If the guest does nothing else it
eventually leads to a a crash on a memcpy from invalid memory address.
However if a guest code can cause the vm to be destroyed in another
vcpu with excellent timing, then kvm_clear_async_pf_completion_queue
can be used by the guest to control the data that's pointed to by the
call to cancel_work_item, which can be used to gain execution.
Fixes: f78146b0f9
Signed-off-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org (3.5+)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Read-only large sptes can be created due to read-only faults as
follows:
- QEMU pagetable entry that maps guest memory is read-only
due to COW.
- Guest read faults such memory, COW is not broken, because
it is a read-only fault.
- Enable dirty logging, large spte not nuked because it is read-only.
- Write-fault on such memory causes guest to loop endlessly
(which must go down to level 1 because dirty logging is enabled).
Fix by dropping large spte when necessary.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Check for invalid state transitions on guest-initiated updates of
MSR_IA32_APICBASE. This address both enabling of the x2APIC when it is
not supported and all invalid transitions as described in SDM section
10.12.5. It also checks that no reserved bit is set in APICBASE by the
guest.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
[Use cpuid_maxphyaddr instead of guest_cpuid_get_phys_bits. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Nothing major here, just bugfixes all over the place. The most
interesting part is the ARM guys' virtualized interrupt controller
overhaul, which lets userspace get/set the state and thus enables
migration of ARM VMs.
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Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
"First round of KVM updates for 3.14; PPC parts will come next week.
Nothing major here, just bugfixes all over the place. The most
interesting part is the ARM guys' virtualized interrupt controller
overhaul, which lets userspace get/set the state and thus enables
migration of ARM VMs"
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (67 commits)
kvm: make KVM_MMU_AUDIT help text more readable
KVM: s390: Fix memory access error detection
KVM: nVMX: Update guest activity state field on L2 exits
KVM: nVMX: Fix nested_run_pending on activity state HLT
KVM: nVMX: Clean up handling of VMX-related MSRs
KVM: nVMX: Add tracepoints for nested_vmexit and nested_vmexit_inject
KVM: nVMX: Pass vmexit parameters to nested_vmx_vmexit
KVM: nVMX: Leave VMX mode on clearing of feature control MSR
KVM: VMX: Fix DR6 update on #DB exception
KVM: SVM: Fix reading of DR6
KVM: x86: Sync DR7 on KVM_SET_DEBUGREGS
add support for Hyper-V reference time counter
KVM: remove useless write to vcpu->hv_clock.tsc_timestamp
KVM: x86: fix tsc catchup issue with tsc scaling
KVM: x86: limit PIT timer frequency
KVM: x86: handle invalid root_hpa everywhere
kvm: Provide kvm_vcpu_eligible_for_directed_yield() stub
kvm: vfio: silence GCC warning
KVM: ARM: Remove duplicate include
arm/arm64: KVM: relax the requirements of VMA alignment for THP
...
Make KVM_MMU_AUDIT kconfig help text readable and collapse
two spaces between words down to one space.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Set guest activity state in L1's VMCS according to the VCPUs mp_state.
This ensures we report the correct state in case we L2 executed HLT or
if we put L2 into HLT state and it was now woken up by an event.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When we suspend the guest in HLT state, the nested run is no longer
pending - we emulated it completely. So only set nested_run_pending
after checking the activity state.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This simplifies the code and also stops issuing warning about writing to
unhandled MSRs when VMX is disabled or the Feature Control MSR is
locked - we do handle them all according to the spec.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Already used by nested SVM for tracing nested vmexit: kvm_nested_vmexit
marks exits from L2 to L0 while kvm_nested_vmexit_inject marks vmexits
that are reflected to L1.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Instead of fixing up the vmcs12 after the nested vmexit, pass key
parameters already when calling nested_vmx_vmexit. This will help
tracing those vmexits.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When userspace sets MSR_IA32_FEATURE_CONTROL to 0, make sure we leave
root and non-root mode, fully disabling VMX. The register state of the
VCPU is undefined after this step, so userspace has to set it to a
proper state afterward.
This enables to reboot a VM while it is running some hypervisor code.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
According to the SDM, only bits 0-3 of DR6 "may" be cleared by "certain"
debug exception. So do update them on #DB exception in KVM, but leave
the rest alone, only setting BD and BS in addition to already set bits
in DR6. This also aligns us with kvm_vcpu_check_singlestep.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In contrast to VMX, SVM dose not automatically transfer DR6 into the
VCPU's arch.dr6. So if we face a DR6 read, we must consult a new vendor
hook to obtain the current value. And as SVM now picks the DR6 state
from its VMCB, we also need a set callback in order to write updates of
DR6 back.
Fixes a regression of 020df0794f.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Whenever we change arch.dr7, we also have to call kvm_update_dr7. In
case guest debugging is off, this will synchronize the new state into
hardware.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off: Peter Lieven <pl@kamp.de>
Signed-off: Gleb Natapov
Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>
After some consideration I decided to submit only Hyper-V reference
counters support this time. I will submit iTSC support as a separate
patch as soon as it is ready.
v1 -> v2
1. mark TSC page dirty as suggested by
Eric Northup <digitaleric@google.com> and Gleb
2. disable local irq when calling get_kernel_ns,
as it was done by Peter Lieven <pl@amp.de>
3. move check for TSC page enable from second patch
to this one.
v3 -> v4
Get rid of ref counter offset.
v4 -> v5
replace __copy_to_user with kvm_write_guest
when updateing iTSC page.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After the previous patch from Marcelo, the comment before this write
became obsolete. In fact, the write is unnecessary. The calls to
kvm_write_tsc ultimately result in a master clock update as soon as
all TSCs agree and the master clock is re-enabled. This master
clock update will rewrite tsc_timestamp.
So, together with the comment, delete the dead write too.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
To fix a problem related to different resolution of TSC and system clock,
the offset in TSC units is approximated by
delta = vcpu->hv_clock.tsc_timestamp - vcpu->last_guest_tsc
(Guest TSC value at (Guest TSC value at last VM-exit)
the last kvm_guest_time_update
call)
Delta is then later scaled using mult,shift pair found in hv_clock
structure (which is correct against tsc_timestamp in that
structure).
However, if a frequency change is performed between these two points,
this delta is measured using different TSC frequencies, but scaled using
mult,shift pair for one frequency only.
The end result is an incorrect delta.
The bug which this code works around is not the only cause for
clock backwards events. The global accumulator is still
necessary, so remove the max_kernel_ns fix and rely on the
global accumulator for no clock backwards events.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit e66d2ae7c6 moved the assignment
vcpu->arch.apic_base = value above a condition with
(vcpu->arch.apic_base ^ value), causing that check
to always fail. Use old_value, vcpu->arch.apic_base's
old value, in the condition instead.
Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Limit PIT timer frequency similarly to the limit applied by
LAPIC timer.
Cc: stable@kernel.org
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
After free_loaded_vmcs executes, the "loaded_vmcs" structure
is kfreed, and now vmx->loaded_vmcs points to a kfreed area.
Subsequent free_loaded_vmcs then attempts to manipulate
vmx->loaded_vmcs.
Switch the order to avoid the problem.
https://bugzilla.redhat.com/show_bug.cgi?id=1047892
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
fix the 'vcpi' typos when apic_debug is enabled.
Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
According to Table C-1 of Intel SDM 3C, a VM exit happens on an I/O instruction when
"use I/O bitmaps" VM-execution control was 0 _and_ the "unconditional I/O exiting"
VM-execution control was 1. So we can't just check "unconditional I/O exiting" alone.
This patch was improved by suggestion from Jan Kiszka.
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Zhihui Zhang <zzhsuny@gmail.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Three reasons for doing this: 1. arch.walk_mmu points to arch.mmu anyway
in case nested EPT wasn't in use. 2. this aligns VMX with SVM. But 3. is
most important: nested_cpu_has_ept(vmcs12) queries the VMCS page, and if
one guest VCPU manipulates the page of another VCPU in L2, we may be
fooled to skip over the nested_ept_uninit_mmu_context, leaving mmu in
nested state. That can crash the host later on if nested_ept_get_cr3 is
invoked while L1 already left vmxon and nested.current_vmcs12 became
NULL therefore.
Cc: stable@kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Update arch.apic_base before triggering recalculate_apic_map. Otherwise
the recalculation will work against the previous state of the APIC and
will fail to build the correct map when an APIC is hardware-enabled
again.
This fixes a regression of 1e08ec4a13.
Cc: stable@vger.kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
It is possible for __direct_map to be called on invalid root_hpa
(-1), two examples:
1) try_async_pf -> can_do_async_pf
-> vmx_interrupt_allowed -> nested_vmx_vmexit
2) vmx_handle_exit -> vmx_interrupt_allowed -> nested_vmx_vmexit
Then to load_vmcs12_host_state and kvm_mmu_reset_context.
Check for this possibility, let fault exception be regenerated.
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=924916
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
If kvm_get_dr or kvm_set_dr reports that it raised a fault, we must not
advance the instruction pointer. Otherwise the exception will hit the
wrong instruction.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It's a pathological case, but still a valid one: If L1 disables APIC
virtualization and also allows L2 to directly write to the APIC page, we
have to forcibly enable APIC virtualization while in L2 if the in-kernel
APIC is in use.
This allows to run the direct interrupt test case in the vmx unit test
without x2APIC.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Giving proper names to the 0 and 1 was once suggested. But since 0 is
returned to the userspace, giving it another name can introduce extra
confusion. This patch just explains the meanings instead.
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Since the commit 15ad7146 ("KVM: Use the scheduler preemption notifiers
to make kvm preemptible"), the remaining stuff in this function is a
simple cond_resched() call with an extra need_resched() check which was
there to avoid dropping VCPUs unnecessarily. Now it is meaningless.
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A guest can cause a BUG_ON() leading to a host kernel crash.
When the guest writes to the ICR to request an IPI, while in x2apic
mode the following things happen, the destination is read from
ICR2, which is a register that the guest can control.
kvm_irq_delivery_to_apic_fast uses the high 16 bits of ICR2 as the
cluster id. A BUG_ON is triggered, which is a protection against
accessing map->logical_map with an out-of-bounds access and manages
to avoid that anything really unsafe occurs.
The logic in the code is correct from real HW point of view. The problem
is that KVM supports only one cluster with ID 0 in clustered mode, but
the code that has the bug does not take this into account.
Reported-by: Lars Bull <larsbull@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
In kvm_lapic_sync_from_vapic and kvm_lapic_sync_to_vapic there is the
potential to corrupt kernel memory if userspace provides an address that
is at the end of a page. This patches concerts those functions to use
kvm_write_guest_cached and kvm_read_guest_cached. It also checks the
vapic_address specified by userspace during ioctl processing and returns
an error to userspace if the address is not a valid GPA.
This is generally not guest triggerable, because the required write is
done by firmware that runs before the guest. Also, it only affects AMD
processors and oldish Intel that do not have the FlexPriority feature
(unless you disable FlexPriority, of course; then newer processors are
also affected).
Fixes: b93463aa59 ('KVM: Accelerated apic support')
Reported-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Under guest controllable circumstances apic_get_tmcct will execute a
divide by zero and cause a crash. If the guest cpuid support
tsc deadline timers and performs the following sequence of requests
the host will crash.
- Set the mode to periodic
- Set the TMICT to 0
- Set the mode bits to 11 (neither periodic, nor one shot, nor tsc deadline)
- Set the TMICT to non-zero.
Then the lapic_timer.period will be 0, but the TMICT will not be. If the
guest then reads from the TMCCT then the host will perform a divide by 0.
This patch ensures that if the lapic_timer.period is 0, then the division
does not occur.
Reported-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andrew Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We can easily emulate the HLT activity state for L1: If it decides that
L2 shall be halted on entry, just invoke the normal emulation of halt
after switching to L2. We do not depend on specific host features to
provide this, so we can expose the capability unconditionally.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
VM_(ENTRY|EXIT)_CONTROLS vmcs fields are read/written on each guest
entry but most times it can be avoided since values do not changes.
Keep fields copy in memory to avoid unnecessary reads from vmcs.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We should not be using jump labels before they were initialized. Push back
the callback to until after jump label initialization.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
If a nested guest does a NM fault but its CR0 doesn't contain the TS
flag (because it was already cleared by the guest with L1 aid) then we
have to activate FPU ourselves in L0 and then continue to L2. If TS flag
is set then we fallback on the previous behavior, forward the fault to
L1 if it asked for.
Signed-off-by: Anthoine Bourgeois <bourgeois@bertin.fr>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We need to copy padding to kernel space first before looking at it.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
I noticed that srcu_read_lock/unlock both have a memory barrier,
so just by moving srcu_read_unlock earlier we can get rid of
one call to smp_mb() using smp_mb__after_srcu_read_unlock instead.
Unsurprisingly, the gain is small but measureable using the unit test
microbenchmark:
before
vmcall in the ballpark of 1410 cycles
after
vmcall in the ballpark of 1360 cycles
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Currently cpuid emulation is traced only when executed by intercept.
Move trace point so that emulator invocation is traced too.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
All decode_register() callers check if instruction has rex prefix
to properly decode one byte operand. It make sense to move the check
inside.
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
When I was looking at RHEL5.9's failure to start with
unrestricted_guest=0/emulate_invalid_guest_state=1, I got it working with a
slightly older tree than kvm.git. I now debugged the remaining failure,
which was introduced by commit 660696d1 (KVM: X86 emulator: fix
source operand decoding for 8bit mov[zs]x instructions, 2013-04-24)
introduced a similar mis-emulation to the one in commit 8acb4207 (KVM:
fix sil/dil/bpl/spl in the mod/rm fields, 2013-05-30). The incorrect
decoding occurs in 8-bit movzx/movsx instructions whose 8-bit operand
is sil/dil/bpl/spl.
Needless to say, "movzbl %bpl, %eax" does occur in RHEL5.9's decompression
prolog, just a handful of instructions before finally giving control to
the decompressed vmlinux and getting out of the invalid guest state.
Because OpMem8 bypasses decode_modrm, the same handling of the REX prefix
must be applied to OpMem8.
Reported-by: Michele Baldessari <michele@redhat.com>
Cc: stable@vger.kernel.org
Cc: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Yet another instruction that we fail to emulate, this time found
in Windows 2008R2 32-bit.
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
mst can't be blamed for lack of switch entries: the
issue is with msrs actually.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
