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Re: [Qemu-devel] [PATCH 3/4] KVM/X86: Enable Intel MPX for guest
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH 3/4] KVM/X86: Enable Intel MPX for guest |
Date: |
Fri, 29 Nov 2013 15:33:20 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130923 Thunderbird/17.0.9 |
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index a8ce117..e30d4ce 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -75,7 +75,7 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
> (best->eax | ((u64)best->edx << 32)) &
> host_xcr0 & KVM_SUPPORTED_XCR0;
> vcpu->arch.guest_xstate_size = best->ebx =
> - xstate_required_size(vcpu->arch.guest_supported_xcr0);
> + xstate_required_size(vcpu->arch.xcr0);
> }
>
> kvm_pmu_cpuid_update(vcpu);
> ...
> kvm_put_guest_xcr0(vcpu);
> vcpu->arch.xcr0 = xcr0;
> +
> + if ((xcr0 ^ old_xcr0) & XSTATE_EXTEND_MASK)
> + kvm_update_cpuid(vcpu);
> +
> return 0;
> }
These hunks should be part of the previous patch.
> @@ -5960,6 +5967,9 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
> preempt_disable();
>
> kvm_x86_ops->prepare_guest_switch(vcpu);
> + if (kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) &&
Shouldn't be necessary, setting xcr0 fails unless OSXSAVE=1.
> + (vcpu->arch.xcr0 & (u64)(XSTATE_BNDREGS | XSTATE_BNDCSR)))
> + kvm_x86_ops->fpu_activate(vcpu);
Can you explain this?
> if (vcpu->fpu_active)
> kvm_load_guest_fpu(vcpu);
> kvm_load_guest_xcr0(vcpu);
> diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> index 587fb9e..985e40e 100644
> --- a/arch/x86/kvm/x86.h
> +++ b/arch/x86/kvm/x86.h
> @@ -122,7 +122,8 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt
> *ctxt,
> gva_t addr, void *val, unsigned int bytes,
> struct x86_exception *exception);
>
> -#define KVM_SUPPORTED_XCR0 (XSTATE_FP | XSTATE_SSE | XSTATE_YMM)
> +#define KVM_SUPPORTED_XCR0 (XSTATE_FP | XSTATE_SSE | XSTATE_YMM \
> + | XSTATE_BNDREGS | XSTATE_BNDCSR)
> extern u64 host_xcr0;
>
> extern struct static_key kvm_no_apic_vcpu;
>
Otherwise looks straightforward.
Paolo