Message ID | 1519714664-2649-1-git-send-email-Tianyu.Lan@microsoft.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
2018-02-27 06:57+0000, Tianyu Lan: > From: Lan Tianyu <Tianyu.Lan@microsoft.com> > > This patch is to check sreg value first and then load vcpu in order > to avoid redundant loading/putting vcpu. > > Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com> > --- Patch "KVM: x86: KVM_CAP_SYNC_REGS" made significant changes to the sregs setter, so the patch cannot be applied in current form. I think that moving the X86_CR4_OSXSAVE check to guest_cpuid_has still makes sense, but avoiding the vcpu_load/put would produce worse code elsewhere and avoiding the load/put is not critical as any error is probably going to be the end for this VM. Thanks.
Hi Radim: Thanks for your review. On 3/9/2018 12:15 AM, rkrcmar@redhat.com wrote: > 2018-02-27 06:57+0000, Tianyu Lan: >> From: Lan Tianyu <Tianyu.Lan@microsoft.com> >> >> This patch is to check sreg value first and then load vcpu in order >> to avoid redundant loading/putting vcpu. >> >> Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com> >> --- > > Patch "KVM: x86: KVM_CAP_SYNC_REGS" made significant changes to the > sregs setter, so the patch cannot be applied in current form. > > I think that moving the X86_CR4_OSXSAVE check to guest_cpuid_has still > makes sense, but avoiding the vcpu_load/put would produce worse code > elsewhere and avoiding the load/put is not critical as any error is > probably going to be the end for this VM. > OK. I will update patch.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c8a0b54..46da9ec 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7671,6 +7671,10 @@ EXPORT_SYMBOL_GPL(kvm_task_switch); int kvm_valid_sregs(struct kvm_vcpu *vcpu, struct kvm_sregs *sregs) { + if (!guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) && + (sregs->cr4 & X86_CR4_OSXSAVE)) + return -EINVAL; + if ((sregs->efer & EFER_LME) && (sregs->cr0 & X86_CR0_PG)) { /* * When EFER.LME and CR0.PG are set, the processor is in @@ -7701,14 +7705,10 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, struct desc_ptr dt; int ret = -EINVAL; - vcpu_load(vcpu); - - if (!guest_cpuid_has(vcpu, X86_FEATURE_XSAVE) && - (sregs->cr4 & X86_CR4_OSXSAVE)) - goto out; - if (kvm_valid_sregs(vcpu, sregs)) - goto out; + return ret; + + vcpu_load(vcpu); apic_base_msr.data = sregs->apic_base; apic_base_msr.host_initiated = true;