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

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>

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 73c9672..42abcd3 100644 (file)
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -337,6 +337,7 @@
 #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_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_BRS                        (13*32+31) /* Branch Sampling available */
 

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 1ad3bde..6972e0b 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -60,12 +60,6 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted)
        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
 
 /* 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(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) |
-               __feature_bit(KVM_X86_FEATURE_AMD_PSFD)
+               F(AMD_PSFD)
        );
 
        /*