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SubjectRe: [PATCH v6 2/5] KVM: x86: Add IBPB support
On Thu, Feb 1, 2018 at 1:59 PM, KarimAllah Ahmed <karahmed@amazon.de> wrote:

> @@ -3684,6 +3696,22 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
> case MSR_IA32_TSC:
> kvm_write_tsc(vcpu, msr);
> break;
> + case MSR_IA32_PRED_CMD:
> + if (!msr->host_initiated &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_IBPB))
> + return 1;
> +
> + if (data & ~PRED_CMD_IBPB)
> + return 1;
> +
> + if (!data)
> + break;
> +
> + wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);

Should this be wrmsrl_safe? I don't see where we've verified host
support of this MSR.

> @@ -3342,6 +3369,34 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> case MSR_IA32_TSC:
> kvm_write_tsc(vcpu, msr_info);
> break;
> + case MSR_IA32_PRED_CMD:
> + if (!msr_info->host_initiated &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_IBPB) &&
> + !guest_cpuid_has(vcpu, X86_FEATURE_SPEC_CTRL))
> + return 1;
> +
> + if (data & ~PRED_CMD_IBPB)
> + return 1;
> +
> + if (!data)
> + break;
> +
> + wrmsrl(MSR_IA32_PRED_CMD, PRED_CMD_IBPB);

And here too...wrmsrl_safe?

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