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Wed, 18 Feb 2026 03:42:52 -0800 (PST) X-Received: by 2002:a17:903:1b67:b0:2a0:c35c:572e with SMTP id d9443c01a7336-2ad17501af0mr153308155ad.30.1771414972496; Wed, 18 Feb 2026 03:42:52 -0800 (PST) From: Ani Sinha To: Paolo Bonzini , Marcelo Tosatti , Zhao Liu Cc: Ani Sinha , kraxel@redhat.com, qemu-devel@nongnu.org, kvm@vger.kernel.org Subject: [PATCH v5 02/34] accel/kvm: add confidential class member to indicate guest rebuild capability Date: Wed, 18 Feb 2026 17:11:55 +0530 Message-ID: <20260218114233.266178-3-anisinha@redhat.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20260218114233.266178-1-anisinha@redhat.com> References: <20260218114233.266178-1-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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.043, 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=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham 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: 1771415096269158500 Content-Type: text/plain; charset="utf-8" As a part of the confidential guest reset process, the existing encrypted g= uest state must be made mutable since it would be discarded after reset. A new encrypted and locked guest state must be established after the reset. To th= is end, a new boolean member per confidential guest support class (eg, tdx or sev-snp) is added that will indicate whether its possible to rebuild guest state: bool can_rebuild_guest_state; This is true if rebuilding guest state is possible, false otherwise. A KVM based confidential guest reset is only possible when the existing state is locked but its possible to rebuild guest state. Otherwise, the guest is not resettable. Signed-off-by: Ani Sinha --- include/system/confidential-guest-support.h | 20 ++++++++++++++++++++ system/runstate.c | 6 +++--- target/i386/kvm/tdx.c | 1 + target/i386/sev.c | 1 + 4 files changed, 25 insertions(+), 3 deletions(-) diff --git a/include/system/confidential-guest-support.h b/include/system/c= onfidential-guest-support.h index 0cc8b26e64..5dca717308 100644 --- a/include/system/confidential-guest-support.h +++ b/include/system/confidential-guest-support.h @@ -152,6 +152,11 @@ typedef struct ConfidentialGuestSupportClass { */ int (*get_mem_map_entry)(int index, ConfidentialGuestMemoryMapEntry *e= ntry, Error **errp); + + /* + * is it possible to rebuild the guest state? + */ + bool can_rebuild_guest_state; } ConfidentialGuestSupportClass; =20 static inline int confidential_guest_kvm_init(ConfidentialGuestSupport *cg= s, @@ -167,6 +172,21 @@ static inline int confidential_guest_kvm_init(Confiden= tialGuestSupport *cgs, return 0; } =20 +static inline bool +confidential_guest_can_rebuild_state(ConfidentialGuestSupport *cgs) +{ + ConfidentialGuestSupportClass *klass; + + if (!cgs) { + /* non-confidential guests */ + return true; + } + + klass =3D CONFIDENTIAL_GUEST_SUPPORT_GET_CLASS(cgs); + return klass->can_rebuild_guest_state; + +} + static inline int confidential_guest_kvm_reset(ConfidentialGuestSupport *c= gs, Error **errp) { diff --git a/system/runstate.c b/system/runstate.c index d091a2bddd..13f32bed8c 100644 --- a/system/runstate.c +++ b/system/runstate.c @@ -57,6 +57,7 @@ #include "system/reset.h" #include "system/runstate.h" #include "system/runstate-action.h" +#include "system/confidential-guest-support.h" #include "system/system.h" #include "system/tpm.h" #include "trace.h" @@ -543,8 +544,6 @@ void qemu_system_reset(ShutdownCause reason) */ if (cpus_are_resettable()) { cpu_synchronize_all_post_reset(); - } else { - assert(runstate_check(RUN_STATE_PRELAUNCH)); } =20 vm_set_suspended(false); @@ -697,7 +696,8 @@ void qemu_system_reset_request(ShutdownCause reason) if (reboot_action =3D=3D REBOOT_ACTION_SHUTDOWN && reason !=3D SHUTDOWN_CAUSE_SUBSYSTEM_RESET) { shutdown_requested =3D reason; - } else if (!cpus_are_resettable()) { + } else if (!cpus_are_resettable() && + !confidential_guest_can_rebuild_state(current_machine->cgs)= ) { error_report("cpus are not resettable, terminating"); shutdown_requested =3D reason; } else { diff --git a/target/i386/kvm/tdx.c b/target/i386/kvm/tdx.c index 0161985768..a3e81e1c0c 100644 --- a/target/i386/kvm/tdx.c +++ b/target/i386/kvm/tdx.c @@ -1543,6 +1543,7 @@ static void tdx_guest_class_init(ObjectClass *oc, con= st void *data) X86ConfidentialGuestClass *x86_klass =3D X86_CONFIDENTIAL_GUEST_CLASS(= oc); =20 klass->kvm_init =3D tdx_kvm_init; + klass->can_rebuild_guest_state =3D true; x86_klass->kvm_type =3D tdx_kvm_type; x86_klass->cpu_instance_init =3D tdx_cpu_instance_init; x86_klass->adjust_cpuid_features =3D tdx_adjust_cpuid_features; diff --git a/target/i386/sev.c b/target/i386/sev.c index acdcb9c4e6..66e38ca32e 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -2760,6 +2760,7 @@ sev_common_instance_init(Object *obj) cgs->set_guest_state =3D cgs_set_guest_state; cgs->get_mem_map_entry =3D cgs_get_mem_map_entry; cgs->set_guest_policy =3D cgs_set_guest_policy; + cgs->can_rebuild_guest_state =3D true; =20 QTAILQ_INIT(&sev_common->launch_vmsa); } --=20 2.42.0