Intel enumerates support for PSFD in CPUID.(EAX=7,ECX=2):EDX.PSFD[bit
0]. Report support for this feature in KVM if it is available on the
host.
Presumably, this feature bit, like its AMD counterpart, is not welcome
in cpufeatures.h, so add a local definition of this feature in KVM.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 23 +++++++++++++++++------
1 file changed, 17 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 07be45c5bb93..b5af9e451bef 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -62,6 +62,7 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted)
* This one is tied to SSB in the user API, and not
* visible in /proc/cpuinfo.
*/
+#define KVM_X86_FEATURE_PSFD 0 /* Predictive Store Forwarding Disable */
#define KVM_X86_FEATURE_AMD_PSFD (13*32+28) /* Predictive Store Forwarding Disable */
#define F feature_bit
@@ -677,9 +678,9 @@ void kvm_set_cpu_caps(void)
);
/*
- * AMD has separate bits for each SPEC_CTRL bit.
- * arch/x86/kernel/cpu/bugs.c is kind enough to
- * record that in cpufeatures so use them.
+ * AMD has separate bits for each SPEC_CTRL bit. Except for
+ * PSFD, arch/x86/kernel/cpu/bugs.c is kind enough to record
+ * that in cpufeatures so use them.
*/
if (boot_cpu_has(X86_FEATURE_IBPB))
kvm_cpu_cap_set(X86_FEATURE_AMD_IBPB);
@@ -880,13 +881,13 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
break;
/* function 7 has additional index. */
case 7:
- entry->eax = min(entry->eax, 1u);
+ /* KVM only supports leaf 7 indices 0 through 2. */
+ max_idx = entry->eax = min(entry->eax, 2u);
cpuid_entry_override(entry, CPUID_7_0_EBX);
cpuid_entry_override(entry, CPUID_7_ECX);
cpuid_entry_override(entry, CPUID_7_EDX);
- /* KVM only supports 0x7.0 and 0x7.1, capped above via min(). */
- if (entry->eax == 1) {
+ if (max_idx >= 1) {
entry = do_host_cpuid(array, function, 1);
if (!entry)
goto out;
@@ -896,6 +897,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
entry->ecx = 0;
entry->edx = 0;
}
+ if (max_idx >= 2) {
+ entry = do_host_cpuid(array, function, 2);
+ if (!entry)
+ goto out;
+
+ entry->eax = 0;
+ entry->ebx = 0;
+ entry->ecx = 0;
+ entry->edx &= BIT(KVM_X86_FEATURE_PSFD);
+ }
break;
case 9:
break;
--
2.37.2.672.g94769d06f0-goog
