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x86: KVM: Add common feature flag for AMD's PSFD

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Use a common X86_FEATURE_* flag for AMD's PSFD, and suppress it from
/proc/cpuinfo via the standard method of an empty string instead of
hacking in a one-off "private" #define in KVM.  The request that led to
KVM defining its own flag was really just that the feature not show up
in /proc/cpuinfo, and additional patches+discussions in the interim have
clarified that defining flags in cpufeatures.h purely so that KVM can
advertise features to userspace is ok so long as the kernel already uses
a word to track the associated CPUID leaf.

No functional change intended.

Link: https://lore.kernel.org/all/d1b1e0da-29f0-c443-6c86-9549bbe1c79d@redhat.como
Link: https://lore.kernel.org/all/YxGZH7aOXQF7Pu5q@nazgul.tnic
Link: https://lore.kernel.org/all/Y3O7UYWfOLfJkwM%2F@zn.tnic
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Link: https://lore.kernel.org/r/20230124194519.2893234-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2023-01-24 19:45:19 +00:00
parent 68f7c82ab1
commit 3d8f61bf8b
2 changed files with 2 additions and 7 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/include/asm/cpufeatures.h
View file

@ -337,6 +337,7 @@
#define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */ #define X86_FEATURE_VIRT_SSBD (13*32+25) /* Virtualized Speculative Store Bypass Disable */
#define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */ #define X86_FEATURE_AMD_SSB_NO (13*32+26) /* "" Speculative Store Bypass is fixed in hardware. */
#define X86_FEATURE_CPPC (13*32+27) /* Collaborative Processor Performance Control */ #define X86_FEATURE_CPPC (13*32+27) /* Collaborative Processor Performance Control */
#define X86_FEATURE_AMD_PSFD (13*32+28) /* "" Predictive Store Forwarding Disable */
#define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */ #define X86_FEATURE_BTC_NO (13*32+29) /* "" Not vulnerable to Branch Type Confusion */
#define X86_FEATURE_BRS (13*32+31) /* Branch Sampling available */ #define X86_FEATURE_BRS (13*32+31) /* Branch Sampling available */

8
arch/x86/kvm/cpuid.c
View file

@ -60,12 +60,6 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted)
return ret; return ret;
} }
/*
* This one is tied to SSB in the user API, and not
* visible in /proc/cpuinfo.
*/
#define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */
#define F feature_bit #define F feature_bit
/* Scattered Flag - For features that are scattered by cpufeatures.h. */ /* Scattered Flag - For features that are scattered by cpufeatures.h. */
@ -715,7 +709,7 @@ void kvm_set_cpu_caps(void)
F(CLZERO) | F(XSAVEERPTR) | F(CLZERO) | F(XSAVEERPTR) |
F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) | F(WBNOINVD) | F(AMD_IBPB) | F(AMD_IBRS) | F(AMD_SSBD) | F(VIRT_SSBD) |
F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) | F(AMD_SSB_NO) | F(AMD_STIBP) | F(AMD_STIBP_ALWAYS_ON) |
__feature_bit(KVM_X86_FEATURE_AMD_PSFD) F(AMD_PSFD)
); );
/* /*