Il 18/09/2014 23:24, Marcelo Tosatti ha scritto:
>
> Initilization of L2 guest with -cpu host, on L1 guest with -cpu host
> triggers:
>
> (qemu) KVM: entry failed, hardware error 0x7
> ...
> nested_vmx_run: VMCS MSR_{LOAD,STORE} unsupported
>
> Nested VMX MSR load/store support is not sufficient to
> allow perf for L2 guest.
>
> Until properly fixed, trap CPUID and disable function 0xA.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index e28d798..976e3a5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -774,6 +774,12 @@ void kvm_cpuid(struct kvm_vcpu *vcpu, u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
> if (!best)
> best = check_cpuid_limit(vcpu, function, index);
>
> + /*
> + * Perfmon not yet supported for L2 guest.
> + */
> + if (is_guest_mode(vcpu) && function == 0xa)
> + best = NULL;
> +
> if (best) {
> *eax = best->eax;
> *ebx = best->ebx;
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index e8f08e9..2ab5047 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6986,6 +6986,8 @@ static bool nested_vmx_exit_handled(struct kvm_vcpu *vcpu)
> case EXIT_REASON_TASK_SWITCH:
> return 1;
> case EXIT_REASON_CPUID:
> + if (kvm_register_read(vcpu, VCPU_REGS_RAX) == 0xa)
> + return 0;
> return 1;
> case EXIT_REASON_HLT:
> return nested_cpu_has(vmcs12, CPU_BASED_HLT_EXITING);
>
Nice solution. :)
Paolo
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