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DIR:OUT; SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Jun 2022 23:10:38.6727 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 08acb551-e3b5-411a-1edf-08da5312170e 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: DM6NAM11FT051.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN8PR12MB3380 Precedence: bulk List-ID: X-Mailing-List: linux-crypto@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 --- 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 91d3d24e60d2..01ea257e17d6 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -2820,8 +2820,7 @@ 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) @@ -2909,6 +2908,9 @@ 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)); } @@ -3054,23 +3056,12 @@ 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); @@ -3111,9 +3102,8 @@ 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; @@ -3143,9 +3133,6 @@ 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 @@ -3156,29 +3143,36 @@ 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 7782312a1cda..bd0db4d4a61e 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -197,8 +197,9 @@ 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 {