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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id w9-20020a5d6089000000b0020e5b4ebaecsm13771290wrt.4.2022.06.28.06.28.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Jun 2022 06:28:15 -0700 (PDT) Date: Tue, 28 Jun 2022 14:28:12 +0100 From: "Dr. David Alan Gilbert" To: Ashish Kalra Cc: x86@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, michael.roth@amd.com, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, jarkko@kernel.org Subject: Re: [PATCH Part2 v6 36/49] KVM: SVM: Add support to handle GHCB GPA register VMGEXIT Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/2.2.6 (2022-06-05) Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org * Ashish Kalra (Ashish.Kalra@amd.com) wrote: > From: Brijesh Singh > > 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 > --- > 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) Are the magic 51's in here fixed ? Dave > +#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 c70f3f7e06a8..6de48130e414 100644 > --- a/arch/x86/kvm/svm/sev.c > +++ b/arch/x86/kvm/svm/sev.c > @@ -3331,6 +3331,27 @@ 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; > > @@ -3381,6 +3402,12 @@ int sev_handle_vmgexit(struct kvm_vcpu *vcpu) > return 1; > } > > + /* 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, &exit_code); > if (ret) > return ret; > diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h > index c80352c9c0d6..54ff56cb6125 100644 > --- a/arch/x86/kvm/svm/svm.h > +++ b/arch/x86/kvm/svm/svm.h > @@ -206,6 +206,8 @@ struct vcpu_sev_es_state { > */ > u64 ghcb_sw_exit_info_1; > u64 ghcb_sw_exit_info_2; > + > + u64 ghcb_registered_gpa; > }; > > struct vcpu_svm { > @@ -334,6 +336,11 @@ 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 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK