Messages in this thread | | | Subject | Re: [PATCH v2] KVM: x86: Avoid guest page table walk when gpa_available is set | From | Brijesh Singh <> | Date | Mon, 17 Jul 2017 16:32:28 -0500 |
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Hi Paolo and Radim
Any comments on this patch, I could not find it in 4.13-2 branch.
Please let me know if you want to fix something, or want me to refresh and resend the patch.
- Brijesh
On 05/19/2017 10:12 AM, Brijesh Singh wrote: > From: Brijesh Singh <brijesh.singh@amd.com> > > On AMD hardware when a guest causes a NPF which requires emulation, > the vcpu->arch.gpa_available flag is set to indicate that cr2 contains > a valid GPA. > > Currently, emulator_read_write_onepage() makes use of gpa_available flag > to avoid a guest page walk for a known MMIO regions. Lets not limit > the gpa_available optimization to just MMIO region. The patch extends > the check to avoid page walk whenever gpa_available flag is set. > > Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> > --- > v1: http://marc.info/?l=kvm&m=149304930814202&w=2 > > Changes in v2: > - move gpa_val setting in pf_interception > > arch/x86/include/asm/kvm_host.h | 1 + > arch/x86/kvm/svm.c | 4 ++++ > arch/x86/kvm/x86.c | 14 +++++++------- > 3 files changed, 12 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 695605e..cc87e00 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -678,6 +678,7 @@ struct kvm_vcpu_arch { > > /* GPA available (AMD only) */ > bool gpa_available; > + gpa_t gpa_val; > }; > > struct kvm_lpage_info { > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index c27ac69..27fb563 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -2070,9 +2070,13 @@ static void svm_set_dr7(struct kvm_vcpu *vcpu, unsigned long value) > static int pf_interception(struct vcpu_svm *svm) > { > u64 fault_address = svm->vmcb->control.exit_info_2; > + struct kvm_vcpu *vcpu = &svm->vcpu; > u64 error_code; > int r = 1; > > + /* On #NPF, exit_info_2 contains a valid GPA */ > + vcpu->arch.gpa_val = fault_address; > + > switch (svm->apf_reason) { > default: > error_code = svm->vmcb->control.exit_info_1; > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b54125b..d2d88ed 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4634,16 +4634,16 @@ static int emulator_read_write_onepage(unsigned long addr, void *val, > */ > if (vcpu->arch.gpa_available && > emulator_can_use_gpa(ctxt) && > - vcpu_is_mmio_gpa(vcpu, addr, exception->address, write) && > (addr & ~PAGE_MASK) == (exception->address & ~PAGE_MASK)) { > - gpa = exception->address; > - goto mmio; > - } > + gpa = vcpu->arch.gpa_val; > + ret = vcpu_is_mmio_gpa(vcpu, addr, gpa, write); > + } else { > > - ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); > + ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); > > - if (ret < 0) > - return X86EMUL_PROPAGATE_FAULT; > + if (ret < 0) > + return X86EMUL_PROPAGATE_FAULT; > + } > > /* For APIC access vmexit */ > if (ret) >
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