> -----Original Message----- > From: Avi Kivity [mailto:avi@xxxxxxxxxx] > Sent: Wednesday, September 19, 2012 6:24 PM > To: Hao, Xudong > Cc: Marcelo Tosatti; kvm@xxxxxxxxxxxxxxx; Zhang, Xiantao > Subject: Re: [PATCH v3] kvm/fpu: Enable fully eager restore kvm FPU > > That may be: > > > > static bool lazy_fpu_allowed() > > { > > return !(vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY)); > > } > > Shouldn't it depend on cr4.osxsave as well? > It do need to check cr4.osxsave due to a separate function. static bool lazy_fpu_allowed(struct kvm_vcpu *vcpu) { return !kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) || !(vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY)); } > > > >> On guest entry: > >> if (!lazy_fpu_allowed(vcpu)) > >> kvm_x86_ops->fpu_activate(vcpu); > > > > But we already have that: > > if (vcpu->fpu_active) > kvm_load_guest_fpu(vcpu); > > so why not manage fpu_active to be always set when needed? I don't want > more checks in the entry path. > I means add fpu_active() in kvm_set_xcr(), not in guest entry. Then the fpu_active will be set always when guest initialize xstate. @@ -574,6 +574,9 @@ int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) kvm_inject_gp(vcpu, 0); return 1; } + if (!lazy_fpu_allowed(vcpu)) + kvm_x86_ops->fpu_activate(vcpu); return 0; -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
