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Wed, 14 Dec 2022 20:00:04 +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 CY4PEPF0000C96C.mail.protection.outlook.com (10.167.242.4) 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 20:00:04 +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 14:00:01 -0600 From: Michael Roth To: CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Brijesh Singh Subject: [PATCH RFC v7 43/64] KVM: SVM: Do not use long-lived GHCB map while setting scratch area Date: Wed, 14 Dec 2022 13:40:35 -0600 Message-ID: <20221214194056.161492-44-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: CY4PEPF0000C96C:EE_|CH3PR12MB8403:EE_ X-MS-Office365-Filtering-Correlation-Id: a7c49e37-5d7a-42fd-8f35-08dade0dcb00 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 20:00:04.7004 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: a7c49e37-5d7a-42fd-8f35-08dade0dcb00 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: CY4PEPF0000C96C.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR12MB8403 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Brijesh Singh The setup_vmgexit_scratch() function may rely on a long-lived GHCB mapping if the GHCB shared buffer area was used for the scratch area. In preparation for eliminating the long-lived GHCB mapping, always allocate a buffer for the scratch area so it can be accessed without the GHCB mapping. Signed-off-by: Brijesh Singh Signed-off-by: Ashish Kalra Signed-off-by: Michael Roth --- arch/x86/kvm/svm/sev.c | 74 +++++++++++++++++++----------------------- arch/x86/kvm/svm/svm.h | 3 +- 2 files changed, 36 insertions(+), 41 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 443c5c8aaaf3..d5c6e48055fb 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2918,8 +2918,7 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu) __free_page(virt_to_page(svm->sev_es.vmsa)); skip_vmsa_free: - if (svm->sev_es.ghcb_sa_free) - kvfree(svm->sev_es.ghcb_sa); + kvfree(svm->sev_es.ghcb_sa); } static void dump_ghcb(struct vcpu_svm *svm) @@ -3007,6 +3006,9 @@ static void sev_es_sync_from_ghcb(struct vcpu_svm *svm) control->exit_info_1 = ghcb_get_sw_exit_info_1(ghcb); control->exit_info_2 = ghcb_get_sw_exit_info_2(ghcb); + /* Copy the GHCB scratch area GPA */ + svm->sev_es.ghcb_sa_gpa = ghcb_get_sw_scratch(ghcb); + /* Clear the valid entries fields */ memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap)); } @@ -3152,23 +3154,12 @@ void sev_es_unmap_ghcb(struct vcpu_svm *svm) if (!svm->sev_es.ghcb) return; - if (svm->sev_es.ghcb_sa_free) { - /* - * The scratch area lives outside the GHCB, so there is a - * buffer that, depending on the operation performed, may - * need to be synced, then freed. - */ - if (svm->sev_es.ghcb_sa_sync) { - kvm_write_guest(svm->vcpu.kvm, - ghcb_get_sw_scratch(svm->sev_es.ghcb), - svm->sev_es.ghcb_sa, - svm->sev_es.ghcb_sa_len); - svm->sev_es.ghcb_sa_sync = false; - } - - kvfree(svm->sev_es.ghcb_sa); - svm->sev_es.ghcb_sa = NULL; - svm->sev_es.ghcb_sa_free = false; + /* Sync the scratch buffer area. */ + if (svm->sev_es.ghcb_sa_sync) { + kvm_write_guest(svm->vcpu.kvm, + ghcb_get_sw_scratch(svm->sev_es.ghcb), + svm->sev_es.ghcb_sa, svm->sev_es.ghcb_sa_len); + svm->sev_es.ghcb_sa_sync = false; } trace_kvm_vmgexit_exit(svm->vcpu.vcpu_id, svm->sev_es.ghcb); @@ -3209,9 +3200,8 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) struct ghcb *ghcb = svm->sev_es.ghcb; u64 ghcb_scratch_beg, ghcb_scratch_end; u64 scratch_gpa_beg, scratch_gpa_end; - void *scratch_va; - scratch_gpa_beg = ghcb_get_sw_scratch(ghcb); + scratch_gpa_beg = svm->sev_es.ghcb_sa_gpa; if (!scratch_gpa_beg) { pr_err("vmgexit: scratch gpa not provided\n"); goto e_scratch; @@ -3241,9 +3231,6 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) scratch_gpa_beg, scratch_gpa_end); goto e_scratch; } - - scratch_va = (void *)svm->sev_es.ghcb; - scratch_va += (scratch_gpa_beg - control->ghcb_gpa); } else { /* * The guest memory must be read into a kernel buffer, so @@ -3254,29 +3241,36 @@ static int setup_vmgexit_scratch(struct vcpu_svm *svm, bool sync, u64 len) len, GHCB_SCRATCH_AREA_LIMIT); goto e_scratch; } - scratch_va = kvzalloc(len, GFP_KERNEL_ACCOUNT); - if (!scratch_va) - return -ENOMEM; + } - if (kvm_read_guest(svm->vcpu.kvm, scratch_gpa_beg, scratch_va, len)) { - /* Unable to copy scratch area from guest */ - pr_err("vmgexit: kvm_read_guest for scratch area failed\n"); + if (svm->sev_es.ghcb_sa_alloc_len < len) { + void *scratch_va = kvzalloc(len, GFP_KERNEL_ACCOUNT); - kvfree(scratch_va); - return -EFAULT; - } + if (!scratch_va) + return -ENOMEM; /* - * The scratch area is outside the GHCB. The operation will - * dictate whether the buffer needs to be synced before running - * the vCPU next time (i.e. a read was requested so the data - * must be written back to the guest memory). + * Free the old scratch area and switch to using newly + * allocated. */ - svm->sev_es.ghcb_sa_sync = sync; - svm->sev_es.ghcb_sa_free = true; + kvfree(svm->sev_es.ghcb_sa); + + svm->sev_es.ghcb_sa_alloc_len = len; + svm->sev_es.ghcb_sa = scratch_va; } - svm->sev_es.ghcb_sa = scratch_va; + if (kvm_read_guest(svm->vcpu.kvm, scratch_gpa_beg, svm->sev_es.ghcb_sa, len)) { + /* Unable to copy scratch area from guest */ + pr_err("vmgexit: kvm_read_guest for scratch area failed\n"); + return -EFAULT; + } + + /* + * The operation will dictate whether the buffer needs to be synced + * before running the vCPU next time (i.e. a read was requested so + * the data must be written back to the guest memory). + */ + svm->sev_es.ghcb_sa_sync = sync; svm->sev_es.ghcb_sa_len = len; return 0; diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index ae733188cf87..f53a41e13033 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -209,8 +209,9 @@ struct vcpu_sev_es_state { /* SEV-ES scratch area support */ void *ghcb_sa; u32 ghcb_sa_len; + u64 ghcb_sa_gpa; + u32 ghcb_sa_alloc_len; bool ghcb_sa_sync; - bool ghcb_sa_free; }; struct vcpu_svm {