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Wed, 11 Feb 2026 22:27:07 -0800 (PST) X-Received: by 2002:a17:90b:1b0a:b0:343:e2ba:e8be with SMTP id 98e67ed59e1d1-3568f307a58mr1581626a91.10.1770877626939; Wed, 11 Feb 2026 22:27:06 -0800 (PST) From: Ani Sinha To: "Maciej S. Szmigiero" Cc: kraxel@redhat.com, Ani Sinha , qemu-devel@nongnu.org Subject: [PATCH v4 25/31] hw/hyperv/vmbus: add support for confidential guest reset Date: Thu, 12 Feb 2026 11:55:09 +0530 Message-ID: <20260212062522.99565-26-anisinha@redhat.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20260212062522.99565-1-anisinha@redhat.com> References: <20260212062522.99565-1-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_H5=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: 1770877767045158500 Content-Type: text/plain; charset="utf-8" On confidential guests when the KVM virtual machine file descriptor changes= as a part of the reset process, event file descriptors needs to be reassociated with the new KVM VM file descriptor. This is achieved with the help of a callback handler that gets called when KVM VM file descriptor changes during the confidential guest reset process. This patch is tested on non-confidential platform only. Signed-off-by: Ani Sinha --- hw/hyperv/trace-events | 1 + hw/hyperv/vmbus.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/hw/hyperv/trace-events b/hw/hyperv/trace-events index 7963c215b1..d8c96f18e9 100644 --- a/hw/hyperv/trace-events +++ b/hw/hyperv/trace-events @@ -16,6 +16,7 @@ vmbus_gpadl_torndown(uint32_t gpadl_id) "gpadl #%d" vmbus_open_channel(uint32_t chan_id, uint32_t gpadl_id, uint32_t target_vp= ) "channel #%d gpadl #%d target vp %d" vmbus_channel_open(uint32_t chan_id, uint32_t status) "channel #%d status = %d" vmbus_close_channel(uint32_t chan_id) "channel #%d" +vmbus_handle_vmfd_change(void) "" =20 # hv-balloon hv_balloon_state_change(const char *tostr) "-> %s" diff --git a/hw/hyperv/vmbus.c b/hw/hyperv/vmbus.c index c5bab5d245..64abe4c4c1 100644 --- a/hw/hyperv/vmbus.c +++ b/hw/hyperv/vmbus.c @@ -20,6 +20,7 @@ #include "hw/hyperv/vmbus-bridge.h" #include "hw/core/sysbus.h" #include "exec/cpu-common.h" +#include "system/kvm.h" #include "exec/target_page.h" #include "trace.h" =20 @@ -248,6 +249,12 @@ struct VMBus { * interrupt page */ EventNotifier notifier; + + /* + * Notifier to inform when vmfd is changed as a part of confidential g= uest + * reset mechanism. + */ + NotifierWithReturn vmbus_vmfd_change_notifier; }; =20 static bool gpadl_full(VMBusGpadl *gpadl) @@ -2347,6 +2354,33 @@ static void vmbus_dev_unrealize(DeviceState *dev) free_channels(vdev); } =20 +/* + * If the KVM fd changes because of VM reset in confidential guests, + * reassociate event fd with the new KVM fd. + */ +static int vmbus_handle_vmfd_change(NotifierWithReturn *notifier, + void *data, Error** errp) +{ + VMBus *vmbus =3D container_of(notifier, VMBus, + vmbus_vmfd_change_notifier); + int ret =3D 0; + + /* we are not interested in pre vmfd change notification */ + if (((VmfdChangeNotifier *)data)->pre) { + return 0; + } + + ret =3D hyperv_set_event_flag_handler(VMBUS_EVENT_CONNECTION_ID, + &vmbus->notifier); + /* if we are only using userland event handler, it may already exist */ + if (ret !=3D 0 && ret !=3D -EEXIST) { + error_setg(errp, "hyperv set event handler failed with %d", ret); + } + + trace_vmbus_handle_vmfd_change(); + return ret; +} + static const Property vmbus_dev_props[] =3D { DEFINE_PROP_UUID("instanceid", VMBusDevice, instanceid), }; @@ -2429,6 +2463,9 @@ static void vmbus_realize(BusState *bus, Error **errp) goto clear_event_notifier; } =20 + vmbus->vmbus_vmfd_change_notifier.notify =3D vmbus_handle_vmfd_change; + kvm_vmfd_add_change_notifier(&vmbus->vmbus_vmfd_change_notifier); + return; =20 clear_event_notifier: --=20 2.42.0