2018-02-27 9:30 GMT+08:00 Nadav Amit <nadav.amit@xxxxxxxxx>:
> Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
>
>> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>>
>> 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 <sironi@xxxxxxxxx>
>> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
>> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
>> Cc: Liran Alon <liran.alon@xxxxxxxxxx>
>> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
>> ---
>> 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/x86.c | 19 +++++++++++++++----
>> 2 files changed, 16 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>> index 938d453..6e13f2f 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;
>> + u32 microcode_version;
>>
>> /*
>> * Paging state of the vcpu
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index d4985a9..00af28e 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;
>> @@ -1067,8 +1068,14 @@ static int do_get_msr_feature(struct kvm_vcpu *vcpu, unsigned index, u64 *data)
>> struct kvm_msr_entry msr;
>>
>> msr.index = index;
>> - if (kvm_x86_ops->get_msr_feature(&msr))
>> - return 1;
>> + 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;
>> + }
>>
>> *data = msr.data;
>>
>> @@ -2248,7 +2255,6 @@ 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:
>> @@ -2256,6 +2262,10 @@ 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:
>> @@ -2551,7 +2561,7 @@ 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 = (u64)vcpu->arch.microcode_version;
>
> I think that the shifts are missing here (the version should be on the high
> bits according to intel_get_microcode_revision() ).
You are right, it seems that we all miss it before.
Regards,
Wanpeng Li
