From: Brijesh Singh <brijesh.singh@xxxxxxx> SEV-SNP guests are required to perform a GHCB GPA registration. Before using a GHCB GPA for a vCPU the first time, a guest must register the vCPU GHCB GPA. If hypervisor can work with the guest requested GPA then it must respond back with the same GPA otherwise return -1. On VMEXIT, Verify that GHCB GPA matches with the registered value. If a mismatch is detected then abort the guest. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx> Signed-off-by: Michael Roth <michael.roth@xxxxxxx> --- arch/x86/include/asm/sev-common.h | 8 ++++++++ arch/x86/kvm/svm/sev.c | 27 +++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.h | 7 +++++++ 3 files changed, 42 insertions(+) diff --git a/arch/x86/include/asm/sev-common.h b/arch/x86/include/asm/sev-common.h index 539de6b93420..0a9055cdfae2 100644 --- a/arch/x86/include/asm/sev-common.h +++ b/arch/x86/include/asm/sev-common.h @@ -59,6 +59,14 @@ #define GHCB_MSR_AP_RESET_HOLD_RESULT_POS 12 #define GHCB_MSR_AP_RESET_HOLD_RESULT_MASK GENMASK_ULL(51, 0) +/* Preferred GHCB GPA Request */ +#define GHCB_MSR_PREF_GPA_REQ 0x010 +#define GHCB_MSR_GPA_VALUE_POS 12 +#define GHCB_MSR_GPA_VALUE_MASK GENMASK_ULL(51, 0) + +#define GHCB_MSR_PREF_GPA_RESP 0x011 +#define GHCB_MSR_PREF_GPA_NONE 0xfffffffffffff + /* GHCB GPA Register */ #define GHCB_MSR_REG_GPA_REQ 0x012 #define GHCB_MSR_REG_GPA_REQ_VAL(v) \ diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index e8740c35be39..2613311f4fcc 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3424,6 +3424,27 @@ static int sev_handle_vmgexit_msr_protocol(struct vcpu_svm *svm) GHCB_MSR_INFO_MASK, GHCB_MSR_INFO_POS); break; } + case GHCB_MSR_PREF_GPA_REQ: { + set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_NONE, GHCB_MSR_GPA_VALUE_MASK, + GHCB_MSR_GPA_VALUE_POS); + set_ghcb_msr_bits(svm, GHCB_MSR_PREF_GPA_RESP, GHCB_MSR_INFO_MASK, + GHCB_MSR_INFO_POS); + break; + } + case GHCB_MSR_REG_GPA_REQ: { + u64 gfn; + + gfn = get_ghcb_msr_bits(svm, GHCB_MSR_GPA_VALUE_MASK, + GHCB_MSR_GPA_VALUE_POS); + + svm->sev_es.ghcb_registered_gpa = gfn_to_gpa(gfn); + + set_ghcb_msr_bits(svm, gfn, GHCB_MSR_GPA_VALUE_MASK, + GHCB_MSR_GPA_VALUE_POS); + set_ghcb_msr_bits(svm, GHCB_MSR_REG_GPA_RESP, GHCB_MSR_INFO_MASK, + GHCB_MSR_INFO_POS); + break; + } case GHCB_MSR_TERM_REQ: { u64 reason_set, reason_code; @@ -3490,6 +3511,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) exit_code = ghcb_get_sw_exit_code(ghcb); + /* SEV-SNP guest requires that the GHCB GPA must be registered */ + if (sev_snp_guest(svm->vcpu.kvm) && !ghcb_gpa_is_registered(svm, ghcb_gpa)) { + vcpu_unimpl(&svm->vcpu, "vmgexit: GHCB GPA [%#llx] is not registered.\n", ghcb_gpa); + return -EINVAL; + } + ret = sev_es_validate_vmgexit(svm); if (ret) return ret; diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index cbd4594f1cca..0c655a4d32d5 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -204,6 +204,8 @@ struct vcpu_sev_es_state { u32 ghcb_sa_len; bool ghcb_sa_sync; bool ghcb_sa_free; + + u64 ghcb_registered_gpa; }; struct vcpu_svm { @@ -336,6 +338,11 @@ static inline bool sev_snp_guest(struct kvm *kvm) return sev_es_guest(kvm) && sev->snp_active; } +static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val) +{ + return svm->sev_es.ghcb_registered_gpa == val; +} + static inline void vmcb_mark_all_dirty(struct vmcb *vmcb) { vmcb->control.clean = 0; -- 2.25.1