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5d7c631d92
linux_dsm_epyc7002/arch/x86/kernel
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Shaohua Li 5d7c631d92 x86/apic: Serialize LVTT and TSC_DEADLINE writes 
The APIC LVTT register is MMIO mapped but the TSC_DEADLINE register is an
MSR. The write to the TSC_DEADLINE MSR is not serializing, so it's not
guaranteed that the write to LVTT has reached the APIC before the
TSC_DEADLINE MSR is written. In such a case the write to the MSR is
ignored and as a consequence the local timer interrupt never fires.

The SDM decribes this issue for xAPIC and x2APIC modes. The
serialization methods recommended by the SDM differ.

xAPIC:
 "1. Memory-mapped write to LVT Timer Register, setting bits 18:17 to 10b.
  2. WRMSR to the IA32_TSC_DEADLINE MSR a value much larger than current time-stamp counter.
  3. If RDMSR of the IA32_TSC_DEADLINE MSR returns zero, go to step 2.
  4. WRMSR to the IA32_TSC_DEADLINE MSR the desired deadline."

x2APIC:
 "To allow for efficient access to the APIC registers in x2APIC mode,
  the serializing semantics of WRMSR are relaxed when writing to the
  APIC registers. Thus, system software should not use 'WRMSR to APIC
  registers in x2APIC mode' as a serializing instruction. Read and write
  accesses to the APIC registers will occur in program order. A WRMSR to
  an APIC register may complete before all preceding stores are globally
  visible; software can prevent this by inserting a serializing
  instruction, an SFENCE, or an MFENCE before the WRMSR."

The xAPIC method is to just wait for the memory mapped write to hit
the LVTT by checking whether the MSR write has reached the hardware.
There is no reason why a proper MFENCE after the memory mapped write would
not do the same. Andi Kleen confirmed that MFENCE is sufficient for the
xAPIC case as well.

Issue MFENCE before writing to the TSC_DEADLINE MSR. This can be done
unconditionally as all CPUs which have TSC_DEADLINE also have MFENCE
support.

[ tglx: Massaged the changelog ]

Signed-off-by: Shaohua Li <shli@fb.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
Cc: <Kernel-team@fb.com>
Cc: <lenb@kernel.org>
Cc: <fenghua.yu@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: stable@vger.kernel.org #v3.7+
Link: http://lkml.kernel.org/r/20150909041352.GA2059853@devbig257.prn2.facebook.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2015-09-14 18:29:59 +02:00
..
acpi x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
apic x86/apic: Serialize LVTT and TSC_DEADLINE writes 2015-09-14 18:29:59 +02:00
cpu x86/cpu: Print family/model/stepping in hex 2015-09-13 09:30:07 +02:00
fpu x86/fpu/math-emu: Fix crash in fork() 2015-08-22 10:23:03 +02:00
kprobes Merge branch 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-14 14:37:47 -07:00
.gitignore
alternative.c x86/alternatives: Make optimize_nops() interrupt safe and synced 2015-09-03 21:27:47 +02:00
amd_gart_64.c
amd_nb.c x86/gart: Check for GART support before accessing GART registers 2015-05-06 11:15:53 +02:00
apb_timer.c x86/asm/tsc: Rename native_read_tsc() to rdtsc() 2015-07-06 15:23:28 +02:00
aperture_64.c x86/gart: Check for GART support before accessing GART registers 2015-05-06 11:15:53 +02:00
apm_32.c apm32: Fix cputime == jiffies assumption 2015-07-29 15:44:58 +02:00
asm-offsets_32.c x86: Remove unused TI_cpu 2015-05-05 20:48:02 +02:00
asm-offsets_64.c x86/asm/entry: (Re-)rename __NR_entry_INT80_compat_max to __NR_syscall_compat_max 2015-06-08 23:43:38 +02:00
asm-offsets.c x86: Merge common 32-bit values in asm-offsets.c 2015-05-05 20:48:02 +02:00
audit_64.c
bootflag.c x86: don't use module_init for non-modular core bootflag code 2015-06-16 14:12:34 -04:00
check.c Linux 4.2-rc8 2015-08-25 09:59:19 +02:00
cpuid.c x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
crash_dump_32.c
crash_dump_64.c
crash.c x86/mm: Decouple <linux/vmalloc.h> from <asm/io.h> 2015-06-03 12:02:00 +02:00
devicetree.c Replace module_init with equivalent device_initcall in non modules. 2015-07-02 10:30:48 -07:00
doublefault.c
dumpstack_32.c Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-13 13:23:34 -07:00
dumpstack_64.c x86/kernel: Use kstack_end() in dumpstack_64.c 2015-02-23 18:37:13 +01:00
dumpstack.c Merge branch 'x86-debug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-04-13 13:23:34 -07:00
e820.c The libnvdimm sub-system introduces, in addition to the libnvdimm-core, 2015-06-29 10:34:42 -07:00
early_printk.c x86/earlyprintk: Allow early_printk() to use console style parameters like '115200n8' 2015-07-06 17:33:47 +02:00
early-quirks.c Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-06-26 13:18:51 -07:00
espfix_64.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
ftrace.c
head32.c
head64.c x86/kasan: Fix KASAN shadow region page tables 2015-07-06 14:53:13 +02:00
head_32.S Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-06-22 17:59:09 -07:00
head_64.S x86/kasan: Fix KASAN shadow region page tables 2015-07-06 14:53:13 +02:00
head.c
hpet.c Merge branch 'x86-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 15:42:28 -07:00
hw_breakpoint.c perf/x86/hw_breakpoints: Fix check for kernel-space breakpoints 2015-08-04 10:16:55 +02:00
i386_ksyms_32.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00
i8237.c
i8253.c clockevents/drivers/i8253: Migrate to new 'set-state' interface 2015-08-10 11:40:30 +02:00
i8259.c x86/asm/entry/irq: Clean up IRQn_VECTOR macros 2015-05-10 12:34:28 +02:00
io_delay.c
ioport.c x86/asm/entry: Rename 'init_tss' to 'cpu_tss' 2015-03-06 08:32:58 +01:00
irq_32.c x86/irq: Do not dereference irq descriptor before checking it 2015-08-28 10:30:15 +02:00
irq_64.c x86/irq: Store irq descriptor in vector array 2015-08-06 00:14:59 +02:00
irq_work.c x86: Consolidate irq entering inlines 2015-05-15 16:04:49 +02:00
irq.c Merge branch 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 15:20:51 -07:00
irqinit.c x86/irq: Store irq descriptor in vector array 2015-08-06 00:14:59 +02:00
jump_label.c
kdebugfs.c
kexec-bzimage64.c x86/boot: Obsolete the MCA sys_desc_table 2015-07-21 10:55:11 +02:00
kgdb.c Linux 4.0-rc7 2015-04-08 09:01:54 +02:00
ksysfs.c
kvm.c The bulk of the changes here is for x86. And for once it's not 2015-06-24 09:36:49 -07:00
kvmclock.c x86: kvmclock: set scheduler clock stable 2015-05-29 14:01:52 +02:00
ldt.c x86/ldt: Fix small LDT allocation for Xen 2015-09-14 12:10:50 +02:00
livepatch.c
machine_kexec_32.c
machine_kexec_64.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2015-06-23 14:07:26 -07:00
Makefile Merge branch 'x86-platform-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 10:33:31 -07:00
mcount_64.S
mmconf-fam10h_64.c
module.c x86/mm/KASLR: Propagate KASLR status to kernel proper 2015-04-03 15:26:15 +02:00
mpparse.c x86: Cleanup irq_domain ops 2015-04-24 15:36:55 +02:00
msr.c
nmi_selftest.c
nmi.c Merge branch 'x86/urgent' into x86/asm, before applying dependent patches 2015-07-31 10:23:35 +02:00
paravirt_patch_32.c x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks 2015-07-06 15:23:26 +02:00
paravirt_patch_64.c Merge branch 'locking/core' into x86/core, to prepare for dependent patch 2015-06-03 10:07:35 +02:00
paravirt-spinlocks.c locking/pvqspinlock: Rename QUEUED_SPINLOCK to QUEUED_SPINLOCKS 2015-05-11 09:52:09 +02:00
paravirt.c x86/asm/tsc, x86/paravirt: Remove read_tsc() and read_tscp() paravirt hooks 2015-07-06 15:23:26 +02:00
pci-calgary_64.c
pci-dma.c x86: Deinline dma_free_attrs() 2015-05-05 20:48:02 +02:00
pci-iommu_table.c
pci-nommu.c
pci-swiotlb.c x86/swiotlb: Try coherent allocations with __GFP_NOWARN 2015-06-11 08:28:38 +02:00
pcspeaker.c
perf_regs.c perf/x86/64: Report regs_user->ax too in get_regs_user() 2015-04-11 13:08:53 +02:00
pmem.c libnvdimm: Set numa_node to NVDIMM devices 2015-06-26 11:23:38 -04:00
probe_roms.c
process_32.c x86/vm86: Clean up vm86.h includes 2015-07-31 13:31:10 +02:00
process_64.c x86/ldt: Make modify_ldt() optional 2015-07-31 13:30:45 +02:00
process.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
ptrace.c x86/entry: Move C entry and exit code to arch/x86/entry/common.c 2015-07-07 10:59:05 +02:00
pvclock.c x86: pvclock: Really remove the sched notifier for cross-cpu migrations 2015-04-27 15:49:30 +02:00
quirks.c
reboot_fixups_32.c
reboot.c x86/reboot: Add ASRock Q1900DC-ITX mainboard reboot quirk 2015-04-01 14:08:09 +02:00
relocate_kernel_32.S x86/asm: Optimize unnecessarily wide TEST instructions 2015-03-07 11:12:43 +01:00
relocate_kernel_64.S x86/asm: Replace "MOVQ $imm, %reg" with MOVL 2015-04-01 13:17:39 +02:00
resource.c
rtc.c kernel.h: remove ancient __FUNCTION__ hack 2015-02-12 18:54:13 -08:00
setup_percpu.c
setup.c x86/boot: Obsolete the MCA sys_desc_table 2015-07-21 10:55:11 +02:00
signal_compat.c x86/compat: Move copy_siginfo_*_user32() to signal_compat.c 2015-07-06 15:28:55 +02:00
signal.c Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes 2015-08-18 09:39:47 +02:00
smp.c x86/mce: Clear Local MCE opt-in before kexec 2015-08-13 10:12:52 +02:00
smpboot.c Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 09:33:26 -07:00
stacktrace.c
step.c Merge branch 'x86/urgent' into x86/asm to fix up conflicts and to pick up fixes 2015-08-18 09:39:47 +02:00
sys_x86_64.c x86/mm: Improve AMD Bulldozer ASLR workaround 2015-03-31 10:01:17 +02:00
sysfb_efi.c
sysfb_simplefb.c
sysfb.c
tboot.c
tce_64.c
test_nx.c
test_rodata.c treewide: Fix typo in printk messages 2015-03-06 23:05:39 +01:00
time.c x86/asm/entry: Change all 'user_mode_vm()' calls to 'user_mode()' 2015-03-23 11:14:17 +01:00
tls.c
tls.h
topology.c x86: Drop bogus __ref / __refdata annotations 2015-07-20 18:57:20 +02:00
trace_clock.c x86/asm/tsc: Add rdtsc_ordered() and use it in trivial call sites 2015-07-06 15:23:29 +02:00
tracepoint.c
traps.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
tsc_msr.c
tsc_sync.c x86/asm/tsc/sync: Use rdtsc_ordered() in check_tsc_warp() and drop extra barriers 2015-07-06 15:23:29 +02:00
tsc.c Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2015-09-01 08:40:25 -07:00
uprobes.c uprobes/x86: Make arch_uretprobe_is_alive(RP_CHECK_CALL) more clever 2015-07-31 10:38:06 +02:00
verify_cpu.S
vm86_32.c x86/vm86: Block non-root vm86(old) if mmap_min_addr != 0 2015-09-05 09:01:16 +02:00
vmlinux.lds.S
vsmp_64.c x86: replace __init_or_module with __init in non-modular vsmp_64.c 2015-06-16 14:12:41 -04:00
x86_init.c PCI changes for the v4.2 merge window: 2015-06-23 13:41:24 -07:00
x8664_ksyms_64.c preempt: Use preempt_schedule_context() as the official tracing preemption point 2015-06-07 15:57:42 +02:00