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Tue, 24 Feb 2026 19:51:22 -0800 (PST) X-Received: by 2002:a17:90b:17c8:b0:354:a284:3fff with SMTP id 98e67ed59e1d1-358ae8cfe96mr11145638a91.25.1771991482539; Tue, 24 Feb 2026 19:51:22 -0800 (PST) From: Ani Sinha To: Paolo Bonzini , Marcelo Tosatti , Zhao Liu Cc: Ani Sinha , kraxel@redhat.com, ani@anisinha.ca, kvm@vger.kernel.org, qemu-devel@nongnu.org Subject: [PATCH v6 22/35] i386/sev: add support for confidential guest reset Date: Wed, 25 Feb 2026 09:19:27 +0530 Message-ID: <20260225035000.385950-23-anisinha@redhat.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20260225035000.385950-1-anisinha@redhat.com> References: <20260225035000.385950-1-anisinha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=anisinha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -10 X-Spam_score: -1.1 X-Spam_bar: - X-Spam_report: (-1.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.358, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.659, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1771991562756158500 Content-Type: text/plain; charset="utf-8" When the KVM VM file descriptor changes as a part of the confidential guest reset mechanism, it necessary to create a new confidential guest context and re-encrypt the VM memory. This happens for SEV-ES and SEV-SNP virtual machi= nes as a part of SEV_LAUNCH_FINISH, SEV_SNP_LAUNCH_FINISH operations. A new resettable interface for SEV module has been added. A new reset callb= ack for the reset 'exit' state has been implemented to perform the above operat= ions when the VM file descriptor has changed during VM reset. Tracepoints has been added also for tracing purpose. Signed-off-by: Ani Sinha --- target/i386/sev.c | 58 ++++++++++++++++++++++++++++++++++++++++ target/i386/trace-events | 1 + 2 files changed, 59 insertions(+) diff --git a/target/i386/sev.c b/target/i386/sev.c index b3893e431c..549e624176 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -30,8 +30,10 @@ #include "system/kvm.h" #include "kvm/kvm_i386.h" #include "sev.h" +#include "system/cpus.h" #include "system/system.h" #include "system/runstate.h" +#include "system/reset.h" #include "trace.h" #include "migration/blocker.h" #include "qom/object.h" @@ -86,6 +88,10 @@ typedef struct QEMU_PACKED PaddedSevHashTable { uint8_t padding[ROUND_UP(sizeof(SevHashTable), 16) - sizeof(SevHashTab= le)]; } PaddedSevHashTable; =20 +static void sev_handle_reset(Object *obj, ResetType type); + +SevKernelLoaderContext sev_load_ctx =3D {}; + QEMU_BUILD_BUG_ON(sizeof(PaddedSevHashTable) % 16 !=3D 0); =20 #define SEV_INFO_BLOCK_GUID "00f771de-1a7e-4fcb-890e-68c77e2fb44e" @@ -129,6 +135,7 @@ struct SevCommonState { uint8_t build_id; int sev_fd; SevState state; + ResettableState reset_state; =20 QTAILQ_HEAD(, SevLaunchVmsa) launch_vmsa; }; @@ -1666,6 +1673,11 @@ sev_vm_state_change(void *opaque, bool running, RunS= tate state) error_setg(&sev_mig_blocker, "SEV: Migration is not implemented"); migrate_add_blocker(&sev_mig_blocker, &error_fatal); + /* + * mark SEV guest as resettable so that we can reinitialize + * SEV upon reset. + */ + qemu_register_resettable(OBJECT(sev_common)); } } } @@ -1991,6 +2003,41 @@ static int sev_snp_kvm_init(ConfidentialGuestSupport= *cgs, Error **errp) return 0; } =20 +/* + * handle sev vm reset + */ +static void sev_handle_reset(Object *obj, ResetType type) +{ + SevCommonState *sev_common =3D SEV_COMMON(MACHINE(qdev_get_machine())-= >cgs); + SevCommonStateClass *klass =3D SEV_COMMON_GET_CLASS(sev_common); + + if (!sev_common) { + return; + } + + if (!runstate_is_running()) { + return; + } + + sev_add_kernel_loader_hashes(&sev_load_ctx, &error_fatal); + if (sev_es_enabled() && !sev_snp_enabled()) { + sev_launch_get_measure(NULL, NULL); + } + if (!sev_check_state(sev_common, SEV_STATE_RUNNING)) { + /* this calls sev_snp_launch_finish() etc */ + klass->launch_finish(sev_common); + } + + trace_sev_handle_reset(); + return; +} + +static ResettableState *sev_reset_state(Object *obj) +{ + SevCommonState *sev_common =3D SEV_COMMON(obj); + return &sev_common->reset_state; +} + int sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp) { @@ -2469,6 +2516,8 @@ bool sev_add_kernel_loader_hashes(SevKernelLoaderCont= ext *ctx, Error **errp) return false; } =20 + /* save the context here so that it can be re-used when vm is reset */ + memcpy(&sev_load_ctx, ctx, sizeof(*ctx)); return klass->build_kernel_loader_hashes(sev_common, area, ctx, errp); } =20 @@ -2729,8 +2778,16 @@ static void sev_common_class_init(ObjectClass *oc, const void *data) { ConfidentialGuestSupportClass *klass =3D CONFIDENTIAL_GUEST_SUPPORT_CL= ASS(oc); + ResettableClass *rc =3D RESETTABLE_CLASS(oc); =20 klass->kvm_init =3D sev_common_kvm_init; + /* + * the exit phase makes sure sev handles reset after all legacy resets + * have taken place (in the hold phase) and IGVM has also properly + * set up the boot state. + */ + rc->phases.exit =3D sev_handle_reset; + rc->get_state =3D sev_reset_state; =20 object_class_property_add_str(oc, "sev-device", sev_common_get_sev_device, @@ -2780,6 +2837,7 @@ static const TypeInfo sev_common_info =3D { .abstract =3D true, .interfaces =3D (const InterfaceInfo[]) { { TYPE_USER_CREATABLE }, + { TYPE_RESETTABLE_INTERFACE }, { } } }; diff --git a/target/i386/trace-events b/target/i386/trace-events index 51301673f0..b320f655ee 100644 --- a/target/i386/trace-events +++ b/target/i386/trace-events @@ -14,3 +14,4 @@ kvm_sev_attestation_report(const char *mnonce, const char= *data) "mnonce %s data kvm_sev_snp_launch_start(uint64_t policy, char *gosvw) "policy 0x%" PRIx64= " gosvw %s" kvm_sev_snp_launch_update(uint64_t src, uint64_t gpa, uint64_t len, const = char *type) "src 0x%" PRIx64 " gpa 0x%" PRIx64 " len 0x%" PRIx64 " (%s page= )" kvm_sev_snp_launch_finish(char *id_block, char *id_auth, char *host_data) = "id_block %s id_auth %s host_data %s" +sev_handle_reset(void) "" --=20 2.42.0