diff options
| author | Sean Christopherson <seanjc@google.com> | 2024-11-27 17:34:20 -0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-12-18 14:20:19 -0800 |
| commit | 3fd55b52279531c6211cb1037e929ea890fbeb59 (patch) | |
| tree | 9e483cc2a1448245c422a9cb4a5acab99d859fc6 | |
| parent | 75c489e12d4b90d8aa5ffb34c3c907ef717fe38e (diff) | |
KVM: x86: Pull CPUID capabilities from boot_cpu_data only as needed
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.
Link: https://lore.kernel.org/r/20241128013424.4096668-54-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/cpuid.c | 15 |
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 465e2c1a63e3..55aaa5cb53cf 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -678,21 +678,23 @@ 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) | \ @@ -790,9 +792,6 @@ 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) | |