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SubjectRE: [PATCH] kvm/fpu: Enable eager restore kvm FPU for MPX
Date
Li, Liang Z wrote on 2015-05-20:
> The MPX feature requires eager KVM FPU restore support. We have
> verified that MPX cannot work correctly with the current lazy KVM FPU
> restore mechanism. Eager KVM FPU restore should be enabled if the MPX
> feature is exposed to VM.
>
> Signed-off-by: Liang Li <liang.z.li@intel.com>
> ---
> arch/x86/kvm/vmx.c | 2 ++
> arch/x86/kvm/x86.c | 3 ++-
> 2 files changed, 4 insertions(+), 1 deletion(-)
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index
> f7b6168..e2cccbe 100644 --- a/arch/x86/kvm/vmx.c +++
> b/arch/x86/kvm/vmx.c @@ -8445,6 +8445,8 @@ static struct kvm_vcpu
> *vmx_create_vcpu(struct kvm *kvm, unsigned int id)
> goto free_vmcs;
> }
> + if (vmx_mpx_supported())

Is it better to use guest_cpuid_has_mpx() instead of vmx_mpx_supported()?

> + vmx_fpu_activate(&vmx->vcpu);
> return &vmx->vcpu;
>
> free_vmcs:
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index
> 5f38188..5993f5f 100644 --- a/arch/x86/kvm/x86.c +++
> b/arch/x86/kvm/x86.c @@ -7060,7 +7060,8 @@ void kvm_put_guest_fpu(struct
> kvm_vcpu *vcpu)
> fpu_save_init(&vcpu->arch.guest_fpu);
> __kernel_fpu_end();
> ++vcpu->stat.fpu_reload;
> - kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
> + if (!kvm_x86_ops->mpx_supported())
> + kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
> trace_kvm_fpu(0);
> }


Best regards,
Yang




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