On 28/02/2018 07:03, Wanpeng Li wrote:
> From: Wanpeng Li <wanpen...@tencent.com>
>
> Linux (among the others) has checks to make sure that certain features
> aren't enabled on a certain family/model/stepping if the microcode version
> isn't greater than or equal to a known good version.
>
> By exposing the real microcode version, we're preventing buggy guests that
> don't check that they are running virtualized (i.e., they should trust the
> hypervisor) from disabling features that are effectively not buggy.
>
> Suggested-by: Filippo Sironi <sir...@amazon.de>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Radim Krčmář <rkrc...@redhat.com>
> Cc: Liran Alon <liran.a...@oracle.com>
> Cc: Nadav Amit <nadav.a...@gmail.com>
> Cc: Borislav Petkov <b...@alien8.de>
> Cc: Tom Lendacky <thomas.lenda...@amd.com>
> Signed-off-by: Wanpeng Li <wanpen...@tencent.com>
> ---
> v4 -> v5:
> * microcode_version be u64 and initialized suitable, remote hte shifts
> v3 -> v4:
> * add the shifts back
> v2 -> v3:
> * remove the shifts
> * add the MSR_IA32_UCODE_REV version to the "feature MSRs"
> v1 -> v2:
> * add MSR_IA32_UCODE_REV to emulated_msrs
>
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/svm.c | 4 +---
> arch/x86/kvm/vmx.c | 1 +
> arch/x86/kvm/x86.c | 11 +++++++++--
> 4 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 938d453..df6720f 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -507,6 +507,7 @@ struct kvm_vcpu_arch {
> u64 smi_count;
> bool tpr_access_reporting;
> u64 ia32_xss;
> + u64 microcode_version;
>
> /*
> * Paging state of the vcpu
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f874798..312f33f 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1907,6 +1907,7 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool
> init_event)
> u32 dummy;
> u32 eax = 1;
>
> + vcpu->arch.microcode_version = 0x01000065;
> svm->spec_ctrl = 0;
>
> if (!init_event) {
> @@ -3962,9 +3963,6 @@ static int svm_get_msr(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
>
> msr_info->data = svm->spec_ctrl;
> break;
> - case MSR_IA32_UCODE_REV:
> - msr_info->data = 0x01000065;
> - break;
> case MSR_F15H_IC_CFG: {
>
> int family, model;
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 9968906..2cdbea7 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -5781,6 +5781,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool
> init_event)
> vmx->rmode.vm86_active = 0;
> vmx->spec_ctrl = 0;
>
> + vcpu->arch.microcode_version = 0x100000000ULL;
> vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();
> kvm_set_cr8(vcpu, 0);
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index efc8554..5c93cbc 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1058,6 +1058,7 @@ static unsigned num_emulated_msrs;
> static u32 msr_based_features[] = {
> MSR_IA32_ARCH_CAPABILITIES,
> MSR_F10H_DECFG,
> + MSR_IA32_UCODE_REV,
> };
>
> static unsigned int num_msr_based_features;
> @@ -1065,6 +1066,9 @@ static unsigned int num_msr_based_features;
> static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
> {
> switch (msr->index) {
> + case MSR_IA32_UCODE_REV:
> + rdmsrl(msr->index, msr->data);
> + break;
> default:
> if (kvm_x86_ops->get_msr_feature(msr))
> return 1;
> @@ -2260,7 +2264,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
>
> switch (msr) {
> case MSR_AMD64_NB_CFG:
> - case MSR_IA32_UCODE_REV:
> case MSR_IA32_UCODE_WRITE:
> case MSR_VM_HSAVE_PA:
> case MSR_AMD64_PATCH_LOADER:
> @@ -2268,6 +2271,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> case MSR_AMD64_DC_CFG:
> break;
>
> + case MSR_IA32_UCODE_REV:
> + if (msr_info->host_initiated)
> + vcpu->arch.microcode_version = data;
> + break;
> case MSR_EFER:
> return set_efer(vcpu, data);
> case MSR_K7_HWCR:
> @@ -2563,7 +2570,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct
> msr_data *msr_info)
> msr_info->data = 0;
> break;
> case MSR_IA32_UCODE_REV:
> - msr_info->data = 0x100000000ULL;
> + msr_info->data = vcpu->arch.microcode_version;
> break;
> case MSR_MTRRcap:
> case 0x200 ... 0x2ff:
>
Reviewed-by: Paolo Bonzini <pbonz...@redhat.com>
