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Wed, 14 Dec 2022 20:02:10 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C Received: from SATLEXMB04.amd.com (165.204.84.17) by CY4PEPF0000C96E.mail.protection.outlook.com (10.167.242.6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.5924.10 via Frontend Transport; Wed, 14 Dec 2022 20:02:10 +0000 Received: from localhost (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.34; Wed, 14 Dec 2022 14:02:07 -0600 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Brijesh Singh , Jarkko Sakkinen Subject: [PATCH RFC v7 49/64] KVM: SVM: Introduce ops for the post gfn map and unmap Date: Wed, 14 Dec 2022 13:40:41 -0600 Message-ID: <20221214194056.161492-50-michael.roth@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221214194056.161492-1-michael.roth@amd.com> References: <20221214194056.161492-1-michael.roth@amd.com> MIME-Version: 1.0 X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB03.amd.com (10.181.40.144) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CY4PEPF0000C96E:EE_|SA3PR12MB7879:EE_ X-MS-Office365-Filtering-Correlation-Id: 92d0b10f-74ce-49a8-5f0a-08dade0e1623 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 14 Dec 2022 20:02:10.7578 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 92d0b10f-74ce-49a8-5f0a-08dade0e1623 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000C96E.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA3PR12MB7879 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Brijesh Singh When SEV-SNP is enabled in the guest VM, the guest memory pages can either be a private or shared. A write from the hypervisor goes through the RMP checks. If the CPU sees that hypervisor is attempting to write to a guest private page, then it will trigger an RMP violation #PF. To avoid the RMP violation with GHCB pages, added new post_{map,unmap}_gfn functions to verify if its safe to map GHCB pages. Use kvm->mmu_lock to guard the GHCB against invalidations while being accessed. Need to add generic post_{map,unmap}_gfn() ops that can be used to verify that it's safe to map a given guest page in the hypervisor. Link: https://lore.kernel.org/all/CABpDEukAEGwb9w12enO=fhSbHbchypsOdO2dkR4Jei3wDW6NWg@mail.gmail.com/ Signed-off-by: Brijesh Singh Signed-off-by: Jarkko Sakkinen Signed-off by: Ashish Kalra [mdr: use kvm->mmu_lock instead of a new spinlock, this should guard GHCB page against invalidations] Signed-off-by: Michael Roth --- arch/x86/kvm/svm/sev.c | 40 ++++++++++++++++++++++++++++++++++++++-- arch/x86/kvm/svm/svm.h | 3 +++ 2 files changed, 41 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index abe6444bf5d4..90b509fe1826 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2926,19 +2926,28 @@ static inline int svm_map_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) { struct vmcb_control_area *control = &svm->vmcb->control; u64 gfn = gpa_to_gfn(control->ghcb_gpa); + struct kvm_vcpu *vcpu = &svm->vcpu; - if (kvm_vcpu_map(&svm->vcpu, gfn, map)) { + if (kvm_vcpu_map(vcpu, gfn, map)) { /* Unable to map GHCB from guest */ pr_err("error mapping GHCB GFN [%#llx] from guest\n", gfn); return -EFAULT; } + if (sev_post_map_gfn(vcpu->kvm, map->gfn, map->pfn)) { + kvm_vcpu_unmap(vcpu, map, false); + return -EBUSY; + } + return 0; } static inline void svm_unmap_ghcb(struct vcpu_svm *svm, struct kvm_host_map *map) { - kvm_vcpu_unmap(&svm->vcpu, map, true); + struct kvm_vcpu *vcpu = &svm->vcpu; + + kvm_vcpu_unmap(vcpu, map, true); + sev_post_unmap_gfn(vcpu->kvm, map->gfn, map->pfn); } static void dump_ghcb(struct vcpu_svm *svm) @@ -3875,6 +3884,33 @@ void sev_rmp_page_level_adjust(struct kvm *kvm, gfn_t gfn, int *level) __func__, gfn, *level, rmp_level, ret); } +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) +{ + int level; + + if (!sev_snp_guest(kvm)) + return 0; + + read_lock(&(kvm)->mmu_lock); + + /* If pfn is not added as private then fail */ + if (snp_lookup_rmpentry(pfn, &level) == 1) { + read_unlock(&(kvm)->mmu_lock); + pr_err_ratelimited("failed to map private gfn 0x%llx pfn 0x%llx\n", gfn, pfn); + return -EBUSY; + } + + return 0; +} + +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn) +{ + if (!sev_snp_guest(kvm)) + return; + + read_unlock(&(kvm)->mmu_lock); +} + int sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault) { gfn_t gfn = gpa_to_gfn(gpa); diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index a4d48c3e0f89..aef13c120f2d 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -100,6 +100,7 @@ struct kvm_sev_info { atomic_t migration_in_progress; u64 snp_init_flags; void *snp_context; /* SNP guest context page */ + spinlock_t psc_lock; }; struct kvm_svm { @@ -727,6 +728,8 @@ void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa); void sev_es_unmap_ghcb(struct vcpu_svm *svm); struct page *snp_safe_alloc_page(struct kvm_vcpu *vcpu); void sev_rmp_page_level_adjust(struct kvm *kvm, gfn_t gfn, int *level); +int sev_post_map_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); +void sev_post_unmap_gfn(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn); int sev_fault_is_private(struct kvm *kvm, gpa_t gpa, u64 error_code, bool *private_fault);