| Message ID | 1495206749-25393-1-git-send-email-brijesh.singh@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Fri, May 19, 2017 at 11:12:29AM -0400, 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(-) I havn't checked in detail, but maybe you have: Does that take nesting into account, where we might run on a shadow nested page-table and we actually get a nested gpa (which still needs translation) instead of a normal gpa? Joerg
Hi Jorge, On 05/30/2017 04:05 AM, Joerg Roedel wrote: > On Fri, May 19, 2017 at 11:12:29AM -0400, 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(-) > > I havn't checked in detail, but maybe you have: Does that take nesting > into account, where we might run on a shadow nested page-table and we > actually get a nested gpa (which still needs translation) instead of a > normal gpa? > nesting should not be an issue. all we're doing is avoiding the GVA->GPA translation for the lowest level guest. The nested case should still use the original code path and perform the nested page walk. I have verified the nesting support and it all seem to work just fine. You can find the original gpa_available patch here [1] [1] https://git.kernel.org/pub/scm/virt/kvm/kvm.git/commit/?id=0f89b207b04a1a399e19d35293658e3a571da3d7 -Brijesh
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) >
2017-07-17 16:32-0500, Brijesh Singh: > 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. Sorry, I tried it during the merge window, but it didn't pass tests on VMX and I got distracted by other bugs before looking into the cause. Can you reproduce the fail?
On 07/19/2017 06:19 AM, Radim Krčmář wrote: > 2017-07-17 16:32-0500, Brijesh Singh: >> 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. > > Sorry, I tried it during the merge window, but it didn't pass tests on > VMX and I got distracted by other bugs before looking into the cause. > > Can you reproduce the fail? > No worries, thanks. I can try to reproduce it, are you running kvm-unittest or something different? IIRC, VMX does not set the gpa_available flag hence I am wondering what did I miss in the patch to trigger the failure. I will debug it and let you know. -Brijesh
2017-07-19 08:35-0500, Brijesh Singh: > On 07/19/2017 06:19 AM, Radim Krčmář wrote: > > 2017-07-17 16:32-0500, Brijesh Singh: > > > 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. > > > > Sorry, I tried it during the merge window, but it didn't pass tests on > > VMX and I got distracted by other bugs before looking into the cause. > > > > Can you reproduce the fail? > > > > No worries, thanks. > > I can try to reproduce it, are you running kvm-unittest or something different? I noticed that a linux guest hung in early boot, but at least (io)apic kvm-unit-tests failed as well, IIRC. > IIRC, VMX does not set the gpa_available flag hence I am wondering what did I miss > in the patch to trigger the failure. I will debug it and let you know. It does now, in ept_violation and ept_misconfig, thanks.
On 19/05/2017 17:12, Brijesh Singh wrote: > - vcpu_is_mmio_gpa(vcpu, addr, exception->address, write) && > (addr & ~PAGE_MASK) == (exception->address & ~PAGE_MASK)) { ^^^^^^^^^^^^^^^^^^ I think this should be vcpu->arch.gpa_val. Paolo > - gpa = exception->address; > - goto mmio; > - } > + gpa = vcpu->arch.gpa_val; > + ret = vcpu_is_mmio_gpa(vcpu, addr, gpa, write); > + } else { >
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)