Currently SVM setup is done sequentially in init_vmcb() -> sev_init_vmcb() -> sev_es_init_vmcb() and tries keeping SVM/SEV/SEV-ES bits separated. One of the exceptions is DR intercepts which is for SEV-ES before sev_es_init_vmcb() runs. Move the SEV-ES intercept setup to sev_es_init_vmcb(). From now on set_dr_intercepts()/clr_dr_intercepts() handle SVM/SEV only. Extend the comment about intercepting DR7 which is to prevent the CPU from getting stuck in an infinite #DB loop as described in https://bugzilla.redhat.com/show_bug.cgi?id=1278496 No functional change intended. Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx> Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxx> Reviewed-by: Santosh Shukla <santosh.shukla@xxxxxxx> Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx> --- Changes: v6: * updated the commit log * updated the DR7 intercept comment in the code v5: * updated the comments * removed sev_es_guest() checks from set_dr_intercepts()/clr_dr_intercepts() * removed remaining intercepts from clr_dr_intercepts() --- arch/x86/kvm/svm/sev.c | 11 ++++++ arch/x86/kvm/svm/svm.c | 37 ++++++++------------ 2 files changed, 25 insertions(+), 23 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 981286359b72..744bcc2e6a05 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2948,6 +2948,7 @@ int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in) static void sev_es_init_vmcb(struct vcpu_svm *svm) { + struct vmcb *vmcb = svm->vmcb01.ptr; struct kvm_vcpu *vcpu = &svm->vcpu; svm->vmcb->control.nested_ctl |= SVM_NESTED_CTL_SEV_ES_ENABLE; @@ -2976,6 +2977,16 @@ static void sev_es_init_vmcb(struct vcpu_svm *svm) svm_set_intercept(svm, TRAP_CR4_WRITE); svm_set_intercept(svm, TRAP_CR8_WRITE); + /* + * DR7 access must remain intercepted for an SEV-ES guest to disallow + * the guest kernel set up a #DB on memory that's needed to vector a #DB + * as otherwise the CPU gets stuck in an infinite #DB loop. + */ + vmcb->control.intercepts[INTERCEPT_DR] = 0; + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE); + recalc_intercepts(svm); + /* Can't intercept XSETBV, HV can't modify XCR0 directly */ svm_clr_intercept(svm, INTERCEPT_XSETBV); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index bec6fb82f494..1df99e9f8655 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -694,23 +694,20 @@ static void set_dr_intercepts(struct vcpu_svm *svm) { struct vmcb *vmcb = svm->vmcb01.ptr; - if (!sev_es_guest(svm->vcpu.kvm)) { - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_WRITE); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_WRITE); - } - + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_READ); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR0_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR1_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR2_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR3_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR4_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR5_WRITE); + vmcb_set_intercept(&vmcb->control, INTERCEPT_DR6_WRITE); vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ); vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE); @@ -723,12 +720,6 @@ static void clr_dr_intercepts(struct vcpu_svm *svm) vmcb->control.intercepts[INTERCEPT_DR] = 0; - /* DR7 access must remain intercepted for an SEV-ES guest */ - if (sev_es_guest(svm->vcpu.kvm)) { - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_READ); - vmcb_set_intercept(&vmcb->control, INTERCEPT_DR7_WRITE); - } - recalc_intercepts(svm); } -- 2.40.1
