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| author | Paolo Bonzini <pbonzini@redhat.com> | 2014-09-22 15:17:48 +0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2014-09-24 16:07:57 +0400 |
| commit | c1118b3602c2329671ad5ec8bdf8e374323d6343 (patch) | |
| tree | 57dce6397f2dbf19701fa1a7671abcde453e170b /arch/x86/include/asm/cpufeature.h | |
| parent | 81760dccf8d1fe5b128b58736fe3f56a566133cb (diff) | |
| download | linux-c1118b3602c2329671ad5ec8bdf8e374323d6343.tar.xz | |
x86: kvm: use alternatives for VMCALL vs. VMMCALL if kernel text is read-only
On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA.
In that case, KVM will fail to patch VMCALL instructions to VMMCALL
as required on AMD processors.
The failure mode is currently a divide-by-zero exception, which obviously
is a KVM bug that has to be fixed. However, picking the right instruction
between VMCALL and VMMCALL will be faster and will help if you cannot upgrade
the hypervisor.
Reported-by: Chris Webb <chris@arachsys.com>
Tested-by: Chris Webb <chris@arachsys.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/include/asm/cpufeature.h')
| -rw-r--r-- | arch/x86/include/asm/cpufeature.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index bb9b258d60e7..2075e6c34c78 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -202,6 +202,7 @@ #define X86_FEATURE_DECODEASSISTS ( 8*32+12) /* AMD Decode Assists support */ #define X86_FEATURE_PAUSEFILTER ( 8*32+13) /* AMD filtered pause intercept */ #define X86_FEATURE_PFTHRESHOLD ( 8*32+14) /* AMD pause filter threshold */ +#define X86_FEATURE_VMMCALL ( 8*32+15) /* Prefer vmmcall to vmcall */ /* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 9 */ |