On 04/24/2017 10:52 AM, Brijesh Singh wrote:
On AMD hardware when a guest causes a NFP which requires emulation,
Just realized a typo in patch description, s/NFP/NPF
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 <[email protected]> --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/svm.c | 4 ++++ arch/x86/kvm/x86.c | 26 +++++++++++++++----------- 3 files changed, 20 insertions(+), 11 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 74ef58c..491326d 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -677,6 +677,7 @@ 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 5fba706..8827e4b 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -4159,6 +4159,10 @@ static int handle_exit(struct kvm_vcpu *vcpu) vcpu->arch.gpa_available = (exit_code == SVM_EXIT_NPF); + /* On #NPF, exit_info_2 contain a valid GPA */ + if (vcpu->arch.gpa_available) + vcpu->arch.gpa_val = svm->vmcb->control.exit_info_2; + if (!is_cr_intercept(svm, INTERCEPT_CR0_WRITE)) vcpu->arch.cr0 = svm->vmcb->save.cr0; if (npt_enabled) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ccbd45e..18ec746 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4653,18 +4653,16 @@ static int emulator_read_write_onepage(unsigned long addr, void *val, * occurred. */ 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)) { + emulator_can_use_gpa(ctxt) && + (addr & ~PAGE_MASK) == (exception->address & ~PAGE_MASK)) { gpa = exception->address; - goto mmio; + ret = vcpu_is_mmio_gpa(vcpu, addr, gpa, write); + } else { + ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); + if (ret < 0) + return X86EMUL_PROPAGATE_FAULT; } - ret = vcpu_mmio_gva_to_gpa(vcpu, addr, &gpa, exception, write); - - if (ret < 0) - return X86EMUL_PROPAGATE_FAULT; - /* For APIC access vmexit */ if (ret) goto mmio; @@ -5675,8 +5673,14 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, } restart: - /* Save the faulting GPA (cr2) in the address field */ - ctxt->exception.address = cr2; + /* + * Save the faulting GPA (cr2) in the address field + * NOTE: If gpa_available is set then gpa_val will contain a valid GPA + */ + if (vcpu->arch.gpa_available) + ctxt->exception.address = vcpu->arch.gpa_val; + else + ctxt->exception.address = cr2; r = x86_emulate_insn(ctxt);
