From: Sean Christopherson Date: Fri, 5 Apr 2024 23:55:54 +0000 (-0700) Subject: KVM: x86: Snapshot if a vCPU's vendor model is AMD vs. Intel compatible X-Git-Tag: v6.6.29~32 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=bdda0c17fe9024707b9a560c2a944e68e5730548;p=thirdparty%2Fkernel%2Fstable.git KVM: x86: Snapshot if a vCPU's vendor model is AMD vs. Intel compatible commit fd706c9b1674e2858766bfbf7430534c2b26fbef upstream. Add kvm_vcpu_arch.is_amd_compatible to cache if a vCPU's vendor model is compatible with AMD, i.e. if the vCPU vendor is AMD or Hygon, along with helpers to check if a vCPU is compatible AMD vs. Intel. To handle Intel vs. AMD behavior related to masking the LVTPC entry, KVM will need to check for vendor compatibility on every PMI injection, i.e. querying for AMD will soon be a moderately hot path. Note! This subtly (or maybe not-so-subtly) makes "Intel compatible" KVM's default behavior, both if userspace omits (or never sets) CPUID 0x0 and if userspace sets a completely unknown vendor. One could argue that KVM should treat such vCPUs as not being compatible with Intel *or* AMD, but that would add useless complexity to KVM. KVM needs to do *something* in the face of vendor specific behavior, and so unless KVM conjured up a magic third option, choosing to treat unknown vendors as neither Intel nor AMD means that checks on AMD compatibility would yield Intel behavior, and checks for Intel compatibility would yield AMD behavior. And that's far worse as it would effectively yield random behavior depending on whether KVM checked for AMD vs. Intel vs. !AMD vs. !Intel. And practically speaking, all x86 CPUs follow either Intel or AMD architecture, i.e. "supporting" an unknown third architecture adds no value. Deliberately don't convert any of the existing guest_cpuid_is_intel() checks, as the Intel side of things is messier due to some flows explicitly checking for exactly vendor==Intel, versus some flows assuming anything that isn't "AMD compatible" gets Intel behavior. The Intel code will be cleaned up in the future. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-ID: <20240405235603.1173076-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index fb9f5fa96cc96..ccba66da7a5d7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -828,6 +828,7 @@ struct kvm_vcpu_arch { int cpuid_nent; struct kvm_cpuid_entry2 *cpuid_entries; struct kvm_hypervisor_cpuid kvm_cpuid; + bool is_amd_compatible; /* * FIXME: Drop this macro and use KVM_NR_GOVERNED_FEATURES directly diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index d65f91d0a8bca..77458137cab17 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -362,6 +362,7 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) kvm_update_pv_runtime(vcpu); + vcpu->arch.is_amd_compatible = guest_cpuid_is_amd_or_hygon(vcpu); vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu); vcpu->arch.reserved_gpa_bits = kvm_vcpu_reserved_gpa_bits_raw(vcpu); diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h index 284fa4704553d..57ee789ada141 100644 --- a/arch/x86/kvm/cpuid.h +++ b/arch/x86/kvm/cpuid.h @@ -125,6 +125,16 @@ static inline bool guest_cpuid_is_intel(struct kvm_vcpu *vcpu) return best && is_guest_vendor_intel(best->ebx, best->ecx, best->edx); } +static inline bool guest_cpuid_is_amd_compatible(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.is_amd_compatible; +} + +static inline bool guest_cpuid_is_intel_compatible(struct kvm_vcpu *vcpu) +{ + return !guest_cpuid_is_amd_compatible(vcpu); +} + static inline int guest_cpuid_family(struct kvm_vcpu *vcpu) { struct kvm_cpuid_entry2 *best; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 11c484d72eab2..294775b7383b4 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -4788,7 +4788,7 @@ static void reset_guest_rsvds_bits_mask(struct kvm_vcpu *vcpu, context->cpu_role.base.level, is_efer_nx(context), guest_can_use(vcpu, X86_FEATURE_GBPAGES), is_cr4_pse(context), - guest_cpuid_is_amd_or_hygon(vcpu)); + guest_cpuid_is_amd_compatible(vcpu)); } static void __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 4ed8a7dc05369..cab7680f0d681 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3317,7 +3317,7 @@ static bool is_mci_status_msr(u32 msr) static bool can_set_mci_status(struct kvm_vcpu *vcpu) { /* McStatusWrEn enabled? */ - if (guest_cpuid_is_amd_or_hygon(vcpu)) + if (guest_cpuid_is_amd_compatible(vcpu)) return !!(vcpu->arch.msr_hwcr & BIT_ULL(18)); return false;