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([2a01:e0a:280:24f0:9db0:474c:ff43:9f5c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-442f4a9bed3sm62403055e9.21.2025.05.15.05.59.04 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 May 2025 05:59:05 -0700 (PDT) Message-ID: <90ee0578-44f7-4e42-b69e-934833199eaf@redhat.com> Date: Thu, 15 May 2025 14:59:04 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH V3 07/42] vfio/container: preserve descriptors To: Steve Sistare , qemu-devel@nongnu.org Cc: Alex Williamson , Yi Liu , Eric Auger , Zhenzhong Duan , "Michael S. Tsirkin" , Marcel Apfelbaum , Peter Xu , Fabiano Rosas References: <1747063973-124548-1-git-send-email-steven.sistare@oracle.com> <1747063973-124548-8-git-send-email-steven.sistare@oracle.com> Content-Language: en-US, fr From: =?UTF-8?Q?C=C3=A9dric_Le_Goater?= Autocrypt: addr=clg@redhat.com; keydata= xsFNBFu8o3UBEADP+oJVJaWm5vzZa/iLgpBAuzxSmNYhURZH+guITvSySk30YWfLYGBWQgeo 8NzNXBY3cH7JX3/a0jzmhDc0U61qFxVgrPqs1PQOjp7yRSFuDAnjtRqNvWkvlnRWLFq4+U5t yzYe4SFMjFb6Oc0xkQmaK2flmiJNnnxPttYwKBPd98WfXMmjwAv7QfwW+OL3VlTPADgzkcqj 53bfZ4VblAQrq6Ctbtu7JuUGAxSIL3XqeQlAwwLTfFGrmpY7MroE7n9Rl+hy/kuIrb/TO8n0 ZxYXvvhT7OmRKvbYuc5Jze6o7op/bJHlufY+AquYQ4dPxjPPVUT/DLiUYJ3oVBWFYNbzfOrV RxEwNuRbycttMiZWxgflsQoHF06q/2l4ttS3zsV4TDZudMq0TbCH/uJFPFsbHUN91qwwaN/+ gy1j7o6aWMz+Ib3O9dK2M/j/O/Ube95mdCqN4N/uSnDlca3YDEWrV9jO1mUS/ndOkjxa34ia 70FjwiSQAsyIwqbRO3CGmiOJqDa9qNvd2TJgAaS2WCw/TlBALjVQ7AyoPEoBPj31K74Wc4GS Rm+FSch32ei61yFu6ACdZ12i5Edt+To+hkElzjt6db/UgRUeKfzlMB7PodK7o8NBD8outJGS tsL2GRX24QvvBuusJdMiLGpNz3uqyqwzC5w0Fd34E6G94806fwARAQABzSJDw6lkcmljIExl IEdvYXRlciA8Y2xnQHJlZGhhdC5jb20+wsGRBBMBCAA7FiEEoPZlSPBIlev+awtgUaNDx8/7 7KEFAmTLlVECGwMFCwkIBwICIgIGFQoJCAsCBBYCAwECHgcCF4AACgkQUaNDx8/77KG0eg// S0zIzTcxkrwJ/9XgdcvVTnXLVF9V4/tZPfB7sCp8rpDCEseU6O0TkOVFoGWM39sEMiQBSvyY lHrP7p7E/JYQNNLh441MfaX8RJ5Ul3btluLapm8oHp/vbHKV2IhLcpNCfAqaQKdfk8yazYhh EdxTBlzxPcu+78uE5fF4wusmtutK0JG0sAgq0mHFZX7qKG6LIbdLdaQalZ8CCFMKUhLptW71 xe+aNrn7hScBoOj2kTDRgf9CE7svmjGToJzUxgeh9mIkxAxTu7XU+8lmL28j2L5uNuDOq9vl hM30OT+pfHmyPLtLK8+GXfFDxjea5hZLF+2yolE/ATQFt9AmOmXC+YayrcO2ZvdnKExZS1o8 VUKpZgRnkwMUUReaF/mTauRQGLuS4lDcI4DrARPyLGNbvYlpmJWnGRWCDguQ/LBPpbG7djoy k3NlvoeA757c4DgCzggViqLm0Bae320qEc6z9o0X0ePqSU2f7vcuWN49Uhox5kM5L86DzjEQ RHXndoJkeL8LmHx8DM+kx4aZt0zVfCHwmKTkSTQoAQakLpLte7tWXIio9ZKhUGPv/eHxXEoS 0rOOAZ6np1U/xNR82QbF9qr9TrTVI3GtVe7Vxmff+qoSAxJiZQCo5kt0YlWwti2fFI4xvkOi V7lyhOA3+/3oRKpZYQ86Frlo61HU3r6d9wzOwU0EW7yjdQEQALyDNNMw/08/fsyWEWjfqVhW pOOrX2h+z4q0lOHkjxi/FRIRLfXeZjFfNQNLSoL8j1y2rQOs1j1g+NV3K5hrZYYcMs0xhmrZ KXAHjjDx7FW3sG3jcGjFW5Xk4olTrZwFsZVUcP8XZlArLmkAX3UyrrXEWPSBJCXxDIW1hzwp bV/nVbo/K9XBptT/wPd+RPiOTIIRptjypGY+S23HYBDND3mtfTz/uY0Jytaio9GETj+fFis6 TxFjjbZNUxKpwftu/4RimZ7qL+uM1rG1lLWc9SPtFxRQ8uLvLOUFB1AqHixBcx7LIXSKZEFU CSLB2AE4wXQkJbApye48qnZ09zc929df5gU6hjgqV9Gk1rIfHxvTsYltA1jWalySEScmr0iS YBZjw8Nbd7SxeomAxzBv2l1Fk8fPzR7M616dtb3Z3HLjyvwAwxtfGD7VnvINPbzyibbe9c6g LxYCr23c2Ry0UfFXh6UKD83d5ybqnXrEJ5n/t1+TLGCYGzF2erVYGkQrReJe8Mld3iGVldB7 JhuAU1+d88NS3aBpNF6TbGXqlXGF6Yua6n1cOY2Yb4lO/mDKgjXd3aviqlwVlodC8AwI0Sdu jWryzL5/AGEU2sIDQCHuv1QgzmKwhE58d475KdVX/3Vt5I9kTXpvEpfW18TjlFkdHGESM/Jx IqVsqvhAJkalABEBAAHCwV8EGAECAAkFAlu8o3UCGwwACgkQUaNDx8/77KEhwg//WqVopd5k 8hQb9VVdk6RQOCTfo6wHhEqgjbXQGlaxKHoXywEQBi8eULbeMQf5l4+tHJWBxswQ93IHBQjK yKyNr4FXseUI5O20XVNYDJZUrhA4yn0e/Af0IX25d94HXQ5sMTWr1qlSK6Zu79lbH3R57w9j hQm9emQEp785ui3A5U2Lqp6nWYWXz0eUZ0Tad2zC71Gg9VazU9MXyWn749s0nXbVLcLS0yop s302Gf3ZmtgfXTX/W+M25hiVRRKCH88yr6it+OMJBUndQVAA/fE9hYom6t/zqA248j0QAV/p LHH3hSirE1mv+7jpQnhMvatrwUpeXrOiEw1nHzWCqOJUZ4SY+HmGFW0YirWV2mYKoaGO2YBU wYF7O9TI3GEEgRMBIRT98fHa0NPwtlTktVISl73LpgVscdW8yg9Gc82oe8FzU1uHjU8b10lU XOMHpqDDEV9//r4ZhkKZ9C4O+YZcTFu+mvAY3GlqivBNkmYsHYSlFsbxc37E1HpTEaSWsGfA HQoPn9qrDJgsgcbBVc1gkUT6hnxShKPp4PlsZVMNjvPAnr5TEBgHkk54HQRhhwcYv1T2QumQ izDiU6iOrUzBThaMhZO3i927SG2DwWDVzZltKrCMD1aMPvb3NU8FOYRhNmIFR3fcalYr+9gD uVKe8BVz4atMOoktmt0GWTOC8P4= In-Reply-To: <1747063973-124548-8-git-send-email-steven.sistare@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=clg@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -37 X-Spam_score: -3.8 X-Spam_bar: --- X-Spam_report: (-3.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1.686, 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_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=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+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 5/12/25 17:32, Steve Sistare wrote: > At vfio creation time, save the value of vfio container, group, and device > descriptors in CPR state. On qemu restart, vfio_realize() finds and uses > the saved descriptors, and remembers the reused status for subsequent > patches. The reused status is cleared when vmstate load finishes. > > During reuse, device and iommu state is already configured, so operations > in vfio_realize that would modify the configuration, such as vfio ioctl's, > are skipped. The result is that vfio_realize constructs qemu data > structures that reflect the current state of the device. > > Signed-off-by: Steve Sistare > --- > hw/vfio/container.c | 65 ++++++++++++++++++++++++++++++++++++------- > hw/vfio/cpr-legacy.c | 46 ++++++++++++++++++++++++++++++ > include/hw/vfio/vfio-cpr.h | 9 ++++++ > include/hw/vfio/vfio-device.h | 2 ++ > 4 files changed, 112 insertions(+), 10 deletions(-) > > diff --git a/hw/vfio/container.c b/hw/vfio/container.c > index 85c76da..278a220 100644 > --- a/hw/vfio/container.c > +++ b/hw/vfio/container.c > @@ -31,6 +31,8 @@ > #include "system/reset.h" > #include "trace.h" > #include "qapi/error.h" > +#include "migration/cpr.h" > +#include "migration/blocker.h" > #include "pci.h" > #include "hw/vfio/vfio-container.h" > #include "hw/vfio/vfio-cpr.h" > @@ -414,7 +416,7 @@ static bool vfio_set_iommu(int container_fd, int group_fd, > } > > static VFIOContainer *vfio_create_container(int fd, VFIOGroup *group, > - Error **errp) > + bool cpr_reused, Error **errp) > { > int iommu_type; > const char *vioc_name; > @@ -425,7 +427,11 @@ static VFIOContainer *vfio_create_container(int fd, VFIOGroup *group, > return NULL; > } > > - if (!vfio_set_iommu(fd, group->fd, &iommu_type, errp)) { > + /* > + * If container is reused, just set its type and skip the ioctls, as the > + * container and group are already configured in the kernel. > + */ > + if (!cpr_reused && !vfio_set_iommu(fd, group->fd, &iommu_type, errp)) { > return NULL; > } > > @@ -433,6 +439,7 @@ static VFIOContainer *vfio_create_container(int fd, VFIOGroup *group, > > container = VFIO_IOMMU_LEGACY(object_new(vioc_name)); > container->fd = fd; > + container->cpr.reused = cpr_reused; > container->iommu_type = iommu_type; > return container; > } > @@ -584,7 +591,7 @@ static bool vfio_container_attach_discard_disable(VFIOContainer *container, > } > > static bool vfio_container_group_add(VFIOContainer *container, VFIOGroup *group, > - Error **errp) > + bool cpr_reused, Error **errp) > { > if (!vfio_container_attach_discard_disable(container, group, errp)) { > return false; > @@ -592,6 +599,9 @@ static bool vfio_container_group_add(VFIOContainer *container, VFIOGroup *group, > group->container = container; > QLIST_INSERT_HEAD(&container->group_list, group, container_next); > vfio_group_add_kvm_device(group); > + if (!cpr_reused) { > + cpr_save_fd("vfio_container_for_group", group->groupid, container->fd); > + } Could we avoid the test on cpr_reused always call cpr_save_fd() ? > return true; > } > > @@ -601,6 +611,7 @@ static void vfio_container_group_del(VFIOContainer *container, VFIOGroup *group) > group->container = NULL; > vfio_group_del_kvm_device(group); > vfio_ram_block_discard_disable(container, false); > + cpr_delete_fd("vfio_container_for_group", group->groupid); > } > > static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as, > @@ -613,17 +624,37 @@ static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as, > VFIOIOMMUClass *vioc = NULL; > bool new_container = false; > bool group_was_added = false; > + bool cpr_reused; > > space = vfio_address_space_get(as); > + fd = cpr_find_fd("vfio_container_for_group", group->groupid); > + cpr_reused = (fd > 0); The code above is doing 2 things : it grabs a restored fd and deduces from the fd value that the VM is doing are doing a CPR reboot. Instead of adding this cpr_reused flag, I would prefer to duplicate the code into something like: if (!cpr_reboot) { QLIST_FOREACH(bcontainer, &space->containers, next) { container = container_of(bcontainer, VFIOContainer, bcontainer); if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) { return vfio_container_group_add(container, group, errp); } } fd = qemu_open("/dev/vfio/vfio", O_RDWR, errp); if (fd < 0) { goto fail; } ret = ioctl(fd, VFIO_GET_API_VERSION); if (ret != VFIO_API_VERSION) { error_setg(errp, "supported vfio version: %d, " "reported version: %d", VFIO_API_VERSION, ret); goto fail; } container = vfio_create_container(fd, group, errp); } else { /* ... */ } > + /* > + * If the container is reused, then the group is already attached in the > + * kernel. If a container with matching fd is found, then update the > + * userland group list and return. If not, then after the loop, create > + * the container struct and group list. > + */ > > QLIST_FOREACH(bcontainer, &space->containers, next) { > container = container_of(bcontainer, VFIOContainer, bcontainer); > - if (!ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) { > - return vfio_container_group_add(container, group, errp); > + > + if (cpr_reused) { > + if (!vfio_cpr_container_match(container, group, &fd)) { why do we need to modify fd ? > + continue; > + } > + } else if (ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &container->fd)) { > + continue; > } > + return vfio_container_group_add(container, group, cpr_reused, errp); > + } > + > + if (!cpr_reused) { > + fd = qemu_open("/dev/vfio/vfio", O_RDWR, errp); > } > > - fd = qemu_open("/dev/vfio/vfio", O_RDWR, errp); > if (fd < 0) {> goto fail; > } > @@ -635,7 +666,7 @@ static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as, > goto fail; > } > > - container = vfio_create_container(fd, group, errp); > + container = vfio_create_container(fd, group, cpr_reused, errp); > if (!container) { > goto fail; > } > @@ -655,7 +686,7 @@ static bool vfio_container_connect(VFIOGroup *group, AddressSpace *as, > > vfio_address_space_insert(space, bcontainer); > > - if (!vfio_container_group_add(container, group, errp)) { > + if (!vfio_container_group_add(container, group, cpr_reused, errp)) { > goto fail; > } > group_was_added = true; > @@ -697,6 +728,7 @@ static void vfio_container_disconnect(VFIOGroup *group) > > QLIST_REMOVE(group, container_next); > group->container = NULL; > + cpr_delete_fd("vfio_container_for_group", group->groupid); > > /* > * Explicitly release the listener first before unset container, > @@ -750,7 +782,7 @@ static VFIOGroup *vfio_group_get(int groupid, AddressSpace *as, Error **errp) > group = g_malloc0(sizeof(*group)); > > snprintf(path, sizeof(path), "/dev/vfio/%d", groupid); > - group->fd = qemu_open(path, O_RDWR, errp); > + group->fd = cpr_open_fd(path, O_RDWR, "vfio_group", groupid, NULL, errp); > if (group->fd < 0) { > goto free_group_exit; > } > @@ -782,6 +814,7 @@ static VFIOGroup *vfio_group_get(int groupid, AddressSpace *as, Error **errp) > return group; > > close_fd_exit: > + cpr_delete_fd("vfio_group", groupid); > close(group->fd); > > free_group_exit: > @@ -803,6 +836,7 @@ static void vfio_group_put(VFIOGroup *group) > vfio_container_disconnect(group); > QLIST_REMOVE(group, next); > trace_vfio_group_put(group->fd); > + cpr_delete_fd("vfio_group", group->groupid); > close(group->fd); > g_free(group); > } > @@ -812,8 +846,14 @@ static bool vfio_device_get(VFIOGroup *group, const char *name, > { > g_autofree struct vfio_device_info *info = NULL; > int fd; > + bool cpr_reused; > + > + fd = cpr_find_fd(name, 0); > + cpr_reused = (fd >= 0); > + if (!cpr_reused) { > + fd = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name); > + } > Could we introduce an helper routine to open this file, like we have cpr_open_fd() ? > - fd = ioctl(group->fd, VFIO_GROUP_GET_DEVICE_FD, name); > if (fd < 0) { > error_setg_errno(errp, errno, "error getting device from group %d", > group->groupid); > @@ -857,6 +897,10 @@ static bool vfio_device_get(VFIOGroup *group, const char *name, > vbasedev->group = group; > QLIST_INSERT_HEAD(&group->device_list, vbasedev, next); > > + vbasedev->cpr.reused = cpr_reused; > + if (!cpr_reused) { > + cpr_save_fd(name, 0, fd); Could we avoid the test on cpr_reused always call cpr_save_fd() ? > + } > trace_vfio_device_get(name, info->flags, info->num_regions, info->num_irqs); > > return true; > @@ -870,6 +914,7 @@ static void vfio_device_put(VFIODevice *vbasedev) > QLIST_REMOVE(vbasedev, next); > vbasedev->group = NULL; > trace_vfio_device_put(vbasedev->fd); > + cpr_delete_fd(vbasedev->name, 0); > close(vbasedev->fd); > } > > diff --git a/hw/vfio/cpr-legacy.c b/hw/vfio/cpr-legacy.c > index fac323c..638a8e0 100644 > --- a/hw/vfio/cpr-legacy.c > +++ b/hw/vfio/cpr-legacy.c > @@ -10,6 +10,7 @@ > #include "qemu/osdep.h" > #include "hw/vfio/vfio-container.h" > #include "hw/vfio/vfio-cpr.h" > +#include "hw/vfio/vfio-device.h" > #include "migration/blocker.h" > #include "migration/cpr.h" > #include "migration/migration.h" > @@ -31,10 +32,27 @@ static bool vfio_cpr_supported(VFIOContainer *container, Error **errp) > } > } > > +static int vfio_container_post_load(void *opaque, int version_id) > +{ > + VFIOContainer *container = opaque; > + VFIOGroup *group; > + VFIODevice *vbasedev; > + > + container->cpr.reused = false; > + > + QLIST_FOREACH(group, &container->group_list, container_next) { > + QLIST_FOREACH(vbasedev, &group->device_list, next) { > + vbasedev->cpr.reused = false; > + } > + } > + return 0; > +} > + > static const VMStateDescription vfio_container_vmstate = { > .name = "vfio-container", > .version_id = 0, > .minimum_version_id = 0, > + .post_load = vfio_container_post_load, > .needed = cpr_needed_for_reuse, > .fields = (VMStateField[]) { > VMSTATE_END_OF_LIST() > @@ -68,3 +86,31 @@ void vfio_legacy_cpr_unregister_container(VFIOContainer *container) > migrate_del_blocker(&container->cpr.blocker); > vmstate_unregister(NULL, &vfio_container_vmstate, container); > } > + > +static bool same_device(int fd1, int fd2) > +{ > + struct stat st1, st2; > + > + return !fstat(fd1, &st1) && !fstat(fd2, &st2) && st1.st_dev == st2.st_dev; > +} > + > +bool vfio_cpr_container_match(VFIOContainer *container, VFIOGroup *group, > + int *pfd) > +{ > + if (container->fd == *pfd) { > + return true; > + } > + if (!same_device(container->fd, *pfd)) { > + return false; > + } > + /* > + * Same device, different fd. This occurs when the container fd is > + * cpr_save'd multiple times, once for each groupid, so SCM_RIGHTS > + * produces duplicates. De-dup it. > + */ > + cpr_delete_fd("vfio_container_for_group", group->groupid); > + close(*pfd); > + cpr_save_fd("vfio_container_for_group", group->groupid, container->fd); > + *pfd = container->fd; I am not sure 'pfd' is used afterwards. Is it ? > + return true; > +} > diff --git a/include/hw/vfio/vfio-cpr.h b/include/hw/vfio/vfio-cpr.h > index f864547..1c4f070 100644 > --- a/include/hw/vfio/vfio-cpr.h > +++ b/include/hw/vfio/vfio-cpr.h > @@ -13,10 +13,16 @@ > > typedef struct VFIOContainerCPR { > Error *blocker; > + bool reused; > } VFIOContainerCPR; > > +typedef struct VFIODeviceCPR { > + bool reused; > +} VFIODeviceCPR; > + > struct VFIOContainer; > struct VFIOContainerBase; > +struct VFIOGroup; > > bool vfio_legacy_cpr_register_container(struct VFIOContainer *container, > Error **errp); > @@ -29,4 +35,7 @@ bool vfio_cpr_register_container(struct VFIOContainerBase *bcontainer, > Error **errp); > void vfio_cpr_unregister_container(struct VFIOContainerBase *bcontainer); > > +bool vfio_cpr_container_match(struct VFIOContainer *container, > + struct VFIOGroup *group, int *fd); > + > #endif /* HW_VFIO_VFIO_CPR_H */ > diff --git a/include/hw/vfio/vfio-device.h b/include/hw/vfio/vfio-device.h > index 8bcb3c1..4e4d0b6 100644 > --- a/include/hw/vfio/vfio-device.h > +++ b/include/hw/vfio/vfio-device.h > @@ -28,6 +28,7 @@ > #endif > #include "system/system.h" > #include "hw/vfio/vfio-container-base.h" > +#include "hw/vfio/vfio-cpr.h" > #include "system/host_iommu_device.h" > #include "system/iommufd.h" > > @@ -84,6 +85,7 @@ typedef struct VFIODevice { > VFIOIOASHwpt *hwpt; > QLIST_ENTRY(VFIODevice) hwpt_next; > struct vfio_region_info **reginfo; > + VFIODeviceCPR cpr; > } VFIODevice; > > struct VFIODeviceOps { Thanks, C.