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| author |   Jesse Larrew <jesse.larrew@amd.com> | 2015-03-13 11:03:39 -0500 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2015-03-23 10:16:43 +0100 |
| commit | f77ac507f893fc00c1b9ea0076f3c9e664b0f9ab (patch) | |
| tree | 746da99d0fb1efe66fc2061f34d51dfb71a3a51f /arch/x86/kernel/cpu/mcheck/mce.c | |
| parent | Merge tag 'ras_for_3.21' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras into x86/ras (diff) | |
| download | linux-dev-f77ac507f893fc00c1b9ea0076f3c9e664b0f9ab.tar.xz linux-dev-f77ac507f893fc00c1b9ea0076f3c9e664b0f9ab.zip | |
x86/mce: Use safe MSR accesses for AMD quirk
Certain MSRs are only relevant to a kernel in host mode, and kvm had
chosen not to implement these MSRs at all for guests. If a guest kernel
ever tried to access these MSRs, the result was a general protection
fault.
KVM will be separately patched to return 0 when these MSRs are read,
and this patch ensures that MSR accesses are tolerant of exceptions.
Signed-off-by: Jesse Larrew <jesse.larrew@amd.com>
[ Drop {} braces around loop ]
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Joel Schopp <joel.schopp@amd.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-edac@vger.kernel.org
Link: http://lkml.kernel.org/r/1426262619-5016-1-git-send-email-jesse.larrew@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/mcheck/mce.c')
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce.c | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index d760931a4546..196a1e34fe39 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1541,7 +1541,7 @@ static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c) if (c->x86 == 0x15 && (c->x86_model >= 0x10 && c->x86_model <= 0x1f)) { int i; - u64 val, hwcr; + u64 hwcr; bool need_toggle; u32 msrs[] = { 0x00000413, /* MC4_MISC0 */ @@ -1556,15 +1556,9 @@ static int __mcheck_cpu_apply_quirks(struct cpuinfo_x86 *c) if (need_toggle) wrmsrl(MSR_K7_HWCR, hwcr | BIT(18)); - for (i = 0; i < ARRAY_SIZE(msrs); i++) { - rdmsrl(msrs[i], val); - - /* CntP bit set? */ - if (val & BIT_64(62)) { - val &= ~BIT_64(62); - wrmsrl(msrs[i], val); - } - } + /* Clear CntP bit safely */ + for (i = 0; i < ARRAY_SIZE(msrs); i++) + msr_clear_bit(msrs[i], 62); /* restore old settings */ if (need_toggle) |