Don't memcpy() all of boot_cpu_data.x86_capability, and instead explicitly
fill each kvm_cpu_cap_init leaf during kvm_cpu_cap_init(). While clever,
copying all kernel capabilities risks over-reporting KVM capabilities,
e.g. if KVM added support in __do_cpuid_func(), but neglected to init the
supported set of capabilities.
Note, explicitly grabbing leafs deliberately keeps Linux-defined leafs as
0! KVM should never advertise Linux-defined leafs; any relevant features
that are "real", but scattered, must be gathered in their correct hardware-
defined leaf.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 15 +++++++--------
1 file changed, 7 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2b05a7e61994..3b8ec5e7e39a 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -657,21 +657,23 @@ static __always_inline u32 raw_cpuid_get(struct cpuid_reg cpuid)
}
/*
- * For kernel-defined leafs, mask the boot CPU's pre-populated value. For KVM-
- * defined leafs, explicitly set the leaf, as KVM is the one and only authority.
+ * For kernel-defined leafs, mask KVM's supported feature set with the kernel's
+ * capabilities as well as raw CPUID. For KVM-defined leafs, consult only raw
+ * CPUID, as KVM is the one and only authority (in the kernel).
*/
#define kvm_cpu_cap_init(leaf, mask) \
do { \
const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32); \
const u32 __maybe_unused kvm_cpu_cap_init_in_progress = leaf; \
+ const u32 *kernel_cpu_caps = boot_cpu_data.x86_capability; \
u32 kvm_cpu_cap_passthrough = 0; \
u32 kvm_cpu_cap_synthesized = 0; \
u32 kvm_cpu_cap_emulated = 0; \
\
+ kvm_cpu_caps[leaf] = (mask); \
+ \
if (leaf < NCAPINTS) \
- kvm_cpu_caps[leaf] &= (mask); \
- else \
- kvm_cpu_caps[leaf] = (mask); \
+ kvm_cpu_caps[leaf] &= kernel_cpu_caps[leaf]; \
\
kvm_cpu_caps[leaf] |= kvm_cpu_cap_passthrough; \
kvm_cpu_caps[leaf] &= (raw_cpuid_get(cpuid) | \
@@ -769,9 +771,6 @@ void kvm_set_cpu_caps(void)
BUILD_BUG_ON(sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)) >
sizeof(boot_cpu_data.x86_capability));
- memcpy(&kvm_cpu_caps, &boot_cpu_data.x86_capability,
- sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)));
-
kvm_cpu_cap_init(CPUID_1_ECX,
F(XMM3) |
F(PCLMULQDQ) |
--
2.47.0.338.g60cca15819-goog
