On Tue, Apr 20, 2021, Paolo Bonzini wrote: > From 547d4d4edcd05fdfac6ce650d65db1d42bcd2807 Mon Sep 17 00:00:00 2001 > From: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Date: Tue, 20 Apr 2021 05:49:11 -0400 > Subject: [PATCH 1/3] KVM: SEV: mask CPUID[0x8000001F].eax according to > supported features Your mailer is obviously a bit wonky, took me a while to find this patch :-) > Do not return the SEV-ES bit from KVM_GET_SUPPORTED_CPUID unless > the corresponding module parameter is 1, and clear the memory encryption > leaf completely if SEV is disabled. Impeccable timing, I was planning on refreshing my SEV cleanup series[*] today. There's going to be an annoying conflict with the svm_set_cpu_caps() change (see below), any objecting to folding your unintentional feedback into my series? [*] https://lkml.kernel.org/r/20210306015905.186698-1-seanjc@xxxxxxxxxx > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> > --- > arch/x86/kvm/cpuid.c | 5 ++++- > arch/x86/kvm/cpuid.h | 1 + > arch/x86/kvm/svm/svm.c | 7 +++++++ > 3 files changed, 12 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > index 2ae061586677..d791d1f093ab 100644 > --- a/arch/x86/kvm/cpuid.c > +++ b/arch/x86/kvm/cpuid.c > @@ -944,8 +944,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) > break; > /* Support memory encryption cpuid if host supports it */ > case 0x8000001F: > - if (!boot_cpu_has(X86_FEATURE_SEV)) > + if (!kvm_cpu_cap_has(X86_FEATURE_SEV)) { > entry->eax = entry->ebx = entry->ecx = entry->edx = 0; > + break; > + } > + cpuid_entry_override(entry, CPUID_8000_001F_EAX); I find this easier to read: if (!kvm_cpu_cap_has(X86_FEATURE_SEV)) entry->eax = entry->ebx = entry->ecx = entry->edx = 0; else cpuid_entry_override(entry, CPUID_8000_001F_EAX); > break; > /*Add support for Centaur's CPUID instruction*/ > case 0xC0000000: > diff --git a/arch/x86/kvm/cpuid.h b/arch/x86/kvm/cpuid.h > index 888e88b42e8d..e873a60a4830 100644 > --- a/arch/x86/kvm/cpuid.h > +++ b/arch/x86/kvm/cpuid.h > @@ -99,6 +99,7 @@ static const struct cpuid_reg reverse_cpuid[] = { > [CPUID_7_EDX] = { 7, 0, CPUID_EDX}, > [CPUID_7_1_EAX] = { 7, 1, CPUID_EAX}, > [CPUID_12_EAX] = {0x00000012, 0, CPUID_EAX}, > + [CPUID_8000_001F_EAX] = {0x8000001F, 0, CPUID_EAX}, > }; > > /* > diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > index cd8c333ed2dc..acdb8457289e 100644 > --- a/arch/x86/kvm/svm/svm.c > +++ b/arch/x86/kvm/svm/svm.c > @@ -923,6 +923,13 @@ static __init void svm_set_cpu_caps(void) > if (boot_cpu_has(X86_FEATURE_LS_CFG_SSBD) || > boot_cpu_has(X86_FEATURE_AMD_SSBD)) > kvm_cpu_cap_set(X86_FEATURE_VIRT_SSBD); > + > + /* CPUID 0x8000001F */ > + if (sev) { > + kvm_cpu_cap_set(X86_FEATURE_SEV); > + if (sev_es) > + kvm_cpu_cap_set(X86_FEATURE_SEV_ES); Gah, I completely spaced on the module params in my series, which is more problematic than normal because it also moves "sev" and "sev_es" to sev.c. The easy solution is to add sev_set_cpu_caps(). On the other, this misses SME_COHERENT. I also think it makes sense to call kvm_cpu_cap_mask() for the leaf, even if it's just to crush KVM's caps to zero. However, because of SME_COHERENT and other potential bits in the future, I think I prefer starting with the bits carried over from boot_cpu_data. E.g. kvm_cpu_cap_mask(CPUID_8000_001F_EAX, 0 /* SME */ | F(SEV) | 0 /* VM_PAGE_FLUSH */ | F(SEV_ES) | F(SME_COHERENT)); and (with renamed module params): if (sev_enabled) kvm_cpu_cap_clear(X86_FEATURE_SEV); if (sev_es_enabled) kvm_cpu_cap_clear(X86_FEATURE_SEV_ES); > + } > } > > static __init int svm_hardware_setup(void)
