Re: [PATCH 4/6] KVM: x86: Move MSR_IA32_PRED_CMD WRMSR emulation to common code

Xiaoyao Li
2023-03-27T06:42:05Z

On 3/22/2023 9:14 AM, Sean Christopherson wrote:
> Dedup the handling of MSR_IA32_PRED_CMD across VMX and SVM by moving the
> logic to kvm_set_msr_common(). Now that the MSR interception toggling is
> handled as part of setting guest CPUID, the VMX and SVM paths are
> identical.
>
> Opportunistically massage the code to make it a wee bit denser.
>

Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>

> Signed-off-by: Sean Christopherson <seanjc@google.com>
> ---
> arch/x86/kvm/svm/svm.c | 14 --------------
> arch/x86/kvm/vmx/vmx.c | 14 --------------
> arch/x86/kvm/x86.c | 11 +++++++++++
> 3 files changed, 11 insertions(+), 28 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index f757b436ffae..85bb535fc321 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2942,20 +2942,6 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> */
> set_msr_interception(vcpu, svm->msrpm, MSR_IA32_SPEC_CTRL, 1, 1);
> break;
> - case MSR_IA32_PRED_CMD:
> - if (!msr->host_initiated &&
> - !guest_has_pred_cmd_msr(vcpu))
> - return 1;
> -
> - if (data & ~PRED_CMD_IBPB)
> - return 1;
> - if (!boot_cpu_has(X86_FEATURE_IBPB))
> - return 1;
> - if (!data)
> - break;
> -
> - wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);
> - break;
> case MSR_AMD64_VIRT_SPEC_CTRL:
> if (!msr->host_initiated &&
> !guest_cpuid_has(vcpu, X86_FEATURE_VIRT_SSBD))
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 5c01c76c0d45..29807be219b9 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -2285,20 +2285,6 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> if (data & ~(TSX_CTRL_RTM_DISABLE | TSX_CTRL_CPUID_CLEAR))
> return 1;
> goto find_uret_msr;
> - case MSR_IA32_PRED_CMD:
> - if (!msr_info->host_initiated &&
> - !guest_has_pred_cmd_msr(vcpu))
> - return 1;
> -
> - if (data & ~PRED_CMD_IBPB)
> - return 1;
> - if (!boot_cpu_has(X86_FEATURE_IBPB))
> - return 1;
> - if (!data)
> - break;
> -
> - wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);
> - break;
> case MSR_IA32_CR_PAT:
> if (!kvm_pat_valid(data))
> return 1;
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 237c483b1230..c83ec88da043 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -3617,6 +3617,17 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> vcpu->arch.perf_capabilities = data;
> kvm_pmu_refresh(vcpu);
> return 0;
> + case MSR_IA32_PRED_CMD:
> + if (!msr_info->host_initiated && !guest_has_pred_cmd_msr(vcpu))
> + return 1;
> +
> + if (!boot_cpu_has(X86_FEATURE_IBPB) || (data & ~PRED_CMD_IBPB))
> + return 1;
> + if (!data)
> + break;
> +
> + wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);
> + break;
> case MSR_EFER:
> return set_efer(vcpu, msr_info);
> case MSR_K7_HWCR: