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Fri, 12 Dec 2025 07:05:59 -0800 (PST) X-Google-Smtp-Source: AGHT+IGWsNzyOmhbI8ozEemOrWUsjBMSfwDTixVU/Mg4HYy0dEV3BRd5UWFrhNoGQ5KVYFJW7LkTYQ== X-Received: by 2002:a05:6a20:72a5:b0:342:378e:44af with SMTP id adf61e73a8af0-369afa01e6emr2327917637.41.1765551956702; Fri, 12 Dec 2025 07:05:56 -0800 (PST) From: Ani Sinha To: Paolo Bonzini , Richard Henderson , Eduardo Habkost , "Michael S. Tsirkin" , Marcel Apfelbaum Cc: vkuznets@redhat.com, kraxel@redhat.com, qemu-devel@nongnu.org, Ani Sinha Subject: [PATCH v1 28/28] kvm/clock: add support for confidential guest reset Date: Fri, 12 Dec 2025 20:33:56 +0530 Message-ID: <20251212150359.548787-29-anisinha@redhat.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20251212150359.548787-1-anisinha@redhat.com> References: <20251212150359.548787-1-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=-0.001, 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_H2=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: 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: 1765552154557158500 Content-Type: text/plain; charset="utf-8" Confidential guests change the KVM VM file descriptor upon reset and also c= reate new VCPU file descriptors against the new KVM VM file descriptor. We need to save the clock state from kvm before KVM VM file descriptor changes and res= tore it after. Also after VCPU file descriptors changed, we must call KVM_KVMCLOCK_CTRL on the VCPU file descriptor to inform KVM that the VCPU is in paused state. Signed-off-by: Ani Sinha --- hw/i386/kvm/clock.c | 56 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index f56382717f..91a5a08f05 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -49,6 +49,9 @@ struct KVMClockState { /* whether the 'clock' value was obtained in a host with * reliable KVM_GET_CLOCK */ bool clock_is_reliable; + + NotifierWithReturn kvmclock_vcpufd_change_notifier; + NotifierWithReturn kvmclock_vmfd_pre_change_notifier; }; =20 struct pvclock_vcpu_time_info { @@ -62,6 +65,9 @@ struct pvclock_vcpu_time_info { uint8_t pad[2]; } __attribute__((__packed__)); /* 32 bytes */ =20 +static int kvmclock_set_clock(NotifierWithReturn *notifier, + void *data, Error** errp); + static uint64_t kvmclock_current_nsec(KVMClockState *s) { CPUState *cpu =3D first_cpu; @@ -218,6 +224,51 @@ static void kvmclock_vm_state_change(void *opaque, boo= l running, } } =20 +static int kvmclock_save_clock(NotifierWithReturn *notifier, + void *data, Error** errp) +{ + KVMClockState *s =3D container_of(notifier, KVMClockState, + kvmclock_vmfd_pre_change_notifier); + kvm_update_clock(s); + return 0; +} + +static int kvmclock_set_clock(NotifierWithReturn *notifier, + void *data, Error** errp) +{ + struct kvm_clock_data clock_data =3D {}; + CPUState *cpu; + int ret; + KVMClockState *s =3D container_of(notifier, KVMClockState, + kvmclock_vcpufd_change_notifier); + int cap_clock_ctrl =3D kvm_check_extension(kvm_state, KVM_CAP_KVMCLOCK= _CTRL); + + if (!s->clock_is_reliable) { + uint64_t pvclock_via_mem =3D kvmclock_current_nsec(s); + /* saved clock value before vmfd change is not reliable */ + if (pvclock_via_mem) { + s->clock =3D pvclock_via_mem; + } + } + + clock_data.clock =3D s->clock; + ret =3D kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &clock_data); + if (ret < 0) { + fprintf(stderr, "KVM_SET_CLOCK failed: %s\n", strerror(-ret)); + abort(); + } + + if (!cap_clock_ctrl) { + return 0; + } + CPU_FOREACH(cpu) { + run_on_cpu(cpu, do_kvmclock_ctrl, RUN_ON_CPU_NULL); + } + + return 0; +} + + static void kvmclock_realize(DeviceState *dev, Error **errp) { KVMClockState *s =3D KVM_CLOCK(dev); @@ -229,7 +280,12 @@ static void kvmclock_realize(DeviceState *dev, Error *= *errp) =20 kvm_update_clock(s); =20 + s->kvmclock_vcpufd_change_notifier.notify =3D kvmclock_set_clock; + s->kvmclock_vmfd_pre_change_notifier.notify =3D kvmclock_save_clock; + qemu_add_vm_change_state_handler(kvmclock_vm_state_change, s); + kvm_vcpufd_add_change_notifier(&s->kvmclock_vcpufd_change_notifier); + kvm_vmfd_add_pre_change_notifier(&s->kvmclock_vmfd_pre_change_notifier= ); } =20 static bool kvmclock_clock_is_reliable_needed(void *opaque) --=20 2.42.0