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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id j28-20020a05620a147c00b007743671a41fsm2024685qkl.72.2023.09.27.05.38.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Sep 2023 05:38:31 -0700 (PDT) Message-ID: <933baed7-5a07-246f-7068-fd722d4d2963@redhat.com> Date: Wed, 27 Sep 2023 14:38:27 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v2 06/12] vfio/pci: Introduce vfio_[attach/detach]_device Content-Language: en-US To: "Duan, Zhenzhong" , "qemu-devel@nongnu.org" Cc: "alex.williamson@redhat.com" , "clg@redhat.com" , "jgg@nvidia.com" , "nicolinc@nvidia.com" , "Martins, Joao" , "peterx@redhat.com" , "jasowang@redhat.com" , "Tian, Kevin" , "Liu, Yi L" , "Sun, Yi Y" , "Peng, Chao P" References: <20230926113255.1177834-1-zhenzhong.duan@intel.com> <20230926113255.1177834-7-zhenzhong.duan@intel.com> From: Eric Auger In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=eric.auger@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -35 X-Spam_score: -3.6 X-Spam_bar: --- X-Spam_report: (-3.6 / 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, NICE_REPLY_A=-1.473, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=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: , Reply-To: eric.auger@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 9/27/23 14:32, Duan, Zhenzhong wrote: > >> -----Original Message----- >> From: Eric Auger >> Sent: Wednesday, September 27, 2023 8:23 PM >> Subject: Re: [PATCH v2 06/12] vfio/pci: Introduce vfio_[attach/detach]_device >> >> >> >> On 9/27/23 12:07, Duan, Zhenzhong wrote: >>> Hi Eric, >>> >>>> -----Original Message----- >>>> From: Eric Auger >>>> Sent: Wednesday, September 27, 2023 5:02 PM >>>> Subject: Re: [PATCH v2 06/12] vfio/pci: Introduce vfio_[attach/detach]_device >>>> >>>> Hi Zhenzhong, >>>> >>>> On 9/26/23 13:32, Zhenzhong Duan wrote: >>>>> From: Eric Auger >>>>> >>>>> We want the VFIO devices to be able to use two different >>>>> IOMMU backends, the legacy VFIO one and the new iommufd one. >>>>> >>>>> Introduce vfio_[attach/detach]_device which aim at hiding the >>>>> underlying IOMMU backend (IOCTLs, datatypes, ...). >>>>> >>>>> Once vfio_attach_device completes, the device is attached >>>>> to a security context and its fd can be used. Conversely >>>>> When vfio_detach_device completes, the device has been >>>>> detached from the security context. >>>>> >>>>> At the moment only the implementation based on the legacy >>>>> container/group exists. Let's use it from the vfio-pci device. >>>>> Subsequent patches will handle other devices. >>>>> >>>>> Signed-off-by: Eric Auger >>>>> Signed-off-by: Yi Liu >>>>> Signed-off-by: Zhenzhong Duan >>>>> --- >>>>> include/hw/vfio/vfio-common.h | 3 ++ >>>>> hw/vfio/common.c | 68 +++++++++++++++++++++++++++++++++++ >>>>> hw/vfio/pci.c | 50 +++----------------------- >>>>> hw/vfio/trace-events | 2 +- >>>>> 4 files changed, 77 insertions(+), 46 deletions(-) >>>>> >>>>> diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio- >> common.h >>>>> index c4e7c3b4a7..12fbfbc37d 100644 >>>>> --- a/include/hw/vfio/vfio-common.h >>>>> +++ b/include/hw/vfio/vfio-common.h >>>>> @@ -225,6 +225,9 @@ void vfio_put_group(VFIOGroup *group); >>>>> struct vfio_device_info *vfio_get_device_info(int fd); >>>>> int vfio_get_device(VFIOGroup *group, const char *name, >>>>> VFIODevice *vbasedev, Error **errp); >>>>> +int vfio_attach_device(char *name, VFIODevice *vbasedev, >>>>> + AddressSpace *as, Error **errp); >>>>> +void vfio_detach_device(VFIODevice *vbasedev); >>>>> >>>>> int vfio_kvm_device_add_fd(int fd, Error **errp); >>>>> int vfio_kvm_device_del_fd(int fd, Error **errp); >>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c >>>>> index 959b1362bb..7f3798b152 100644 >>>>> --- a/hw/vfio/common.c >>>>> +++ b/hw/vfio/common.c >>>>> @@ -2611,3 +2611,71 @@ int vfio_eeh_as_op(AddressSpace *as, uint32_t >> op) >>>>> } >>>>> return vfio_eeh_container_op(container, op); >>>>> } >>>>> + >>>>> +static int vfio_device_groupid(VFIODevice *vbasedev, Error **errp) >>>>> +{ >>>>> + char *tmp, group_path[PATH_MAX], *group_name; >>>>> + int ret, groupid; >>>>> + ssize_t len; >>>>> + >>>>> + tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev); >>>>> + len = readlink(tmp, group_path, sizeof(group_path)); >>>>> + g_free(tmp); >>>>> + >>>>> + if (len <= 0 || len >= sizeof(group_path)) { >>>>> + ret = len < 0 ? -errno : -ENAMETOOLONG; >>>>> + error_setg_errno(errp, -ret, "no iommu_group found"); >>>>> + return ret; >>>>> + } >>>>> + >>>>> + group_path[len] = 0; >>>>> + >>>>> + group_name = basename(group_path); >>>>> + if (sscanf(group_name, "%d", &groupid) != 1) { >>>>> + error_setg_errno(errp, errno, "failed to read %s", group_path); >>>>> + return -errno; >>>>> + } >>>>> + return groupid; >>>>> +} >>>>> + >>>>> +int vfio_attach_device(char *name, VFIODevice *vbasedev, >>>>> + AddressSpace *as, Error **errp) >>>>> +{ >>>>> + int groupid = vfio_device_groupid(vbasedev, errp); >>>>> + VFIODevice *vbasedev_iter; >>>>> + VFIOGroup *group; >>>>> + int ret; >>>>> + >>>>> + if (groupid < 0) { >>>>> + return groupid; >>>>> + } >>>>> + >>>>> + trace_vfio_attach_device(vbasedev->name, groupid); >>>>> + >>>>> + group = vfio_get_group(groupid, as, errp); >>>>> + if (!group) { >>>>> + return -ENOENT; >>>>> + } >>>>> + >>>>> + QLIST_FOREACH(vbasedev_iter, &group->device_list, next) { >>>>> + if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) { >>>>> + error_setg(errp, "device is already attached"); >>>>> + vfio_put_group(group); >>>>> + return -EBUSY; >>>>> + } >>>>> + } >>>>> + ret = vfio_get_device(group, name, vbasedev, errp); >>>>> + if (ret) { >>>>> + vfio_put_group(group); >>>>> + } >>>>> + >>>>> + return ret; >>>>> +} >>>>> + >>>>> +void vfio_detach_device(VFIODevice *vbasedev) >>>>> +{ >>>>> + VFIOGroup *group = vbasedev->group; >>>>> + >>>>> + vfio_put_base_device(vbasedev); >>>>> + vfio_put_group(group); >>>>> +} >>>>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c >>>>> index 3b2ca3c24c..fe56789893 100644 >>>>> --- a/hw/vfio/pci.c >>>>> +++ b/hw/vfio/pci.c >>>>> @@ -2828,10 +2828,10 @@ static void vfio_populate_device(VFIOPCIDevice >>>> *vdev, Error **errp) >>>>> static void vfio_put_device(VFIOPCIDevice *vdev) >>>>> { >>>>> + vfio_detach_device(&vdev->vbasedev); >>>>> + >>>>> g_free(vdev->vbasedev.name); >>>>> g_free(vdev->msix); >>>>> - >>>>> - vfio_put_base_device(&vdev->vbasedev); >>>>> } >>>>> >>>>> static void vfio_err_notifier_handler(void *opaque) >>>>> @@ -2978,13 +2978,9 @@ static void vfio_realize(PCIDevice *pdev, Error >>>> **errp) >>>>> { >>>>> VFIOPCIDevice *vdev = VFIO_PCI(pdev); >>>>> VFIODevice *vbasedev = &vdev->vbasedev; >>>>> - VFIODevice *vbasedev_iter; >>>>> - VFIOGroup *group; >>>>> - char *tmp, *subsys, group_path[PATH_MAX], *group_name; >>>>> + char *tmp, *subsys; >>>>> Error *err = NULL; >>>>> - ssize_t len; >>>>> struct stat st; >>>>> - int groupid; >>>>> int i, ret; >>>>> bool is_mdev; >>>>> char uuid[UUID_FMT_LEN]; >>>>> @@ -3015,39 +3011,6 @@ static void vfio_realize(PCIDevice *pdev, Error >>>> **errp) >>>>> vbasedev->type = VFIO_DEVICE_TYPE_PCI; >>>>> vbasedev->dev = DEVICE(vdev); >>>>> >>>>> - tmp = g_strdup_printf("%s/iommu_group", vbasedev->sysfsdev); >>>>> - len = readlink(tmp, group_path, sizeof(group_path)); >>>>> - g_free(tmp); >>>>> - >>>>> - if (len <= 0 || len >= sizeof(group_path)) { >>>>> - error_setg_errno(errp, len < 0 ? errno : ENAMETOOLONG, >>>>> - "no iommu_group found"); >>>>> - goto error; >>>>> - } >>>>> - >>>>> - group_path[len] = 0; >>>>> - >>>>> - group_name = basename(group_path); >>>>> - if (sscanf(group_name, "%d", &groupid) != 1) { >>>>> - error_setg_errno(errp, errno, "failed to read %s", group_path); >>>>> - goto error; >>>>> - } >>>>> - >>>>> - trace_vfio_realize(vbasedev->name, groupid); >>>>> - >>>>> - group = vfio_get_group(groupid, pci_device_iommu_address_space(pdev), >>>> errp); >>>>> - if (!group) { >>>>> - goto error; >>>>> - } >>>>> - >>>>> - QLIST_FOREACH(vbasedev_iter, &group->device_list, next) { >>>>> - if (strcmp(vbasedev_iter->name, vbasedev->name) == 0) { >>>>> - error_setg(errp, "device is already attached"); >>>>> - vfio_put_group(group); >>>>> - goto error; >>>>> - } >>>>> - } >>>>> - >>>>> /* >>>>> * Mediated devices *might* operate compatibly with discarding of RAM, >> but >>>>> * we cannot know for certain, it depends on whether the mdev vendor >>>> driver >>>>> @@ -3065,7 +3028,6 @@ static void vfio_realize(PCIDevice *pdev, Error >> **errp) >>>>> if (vbasedev->ram_block_discard_allowed && !is_mdev) { >>>>> error_setg(errp, "x-balloon-allowed only potentially compatible " >>>>> "with mdev devices"); >>>>> - vfio_put_group(group); >>>>> goto error; >>>>> } >>>>> >>>>> @@ -3076,10 +3038,10 @@ static void vfio_realize(PCIDevice *pdev, Error >>>> **errp) >>>>> name = g_strdup(vbasedev->name); >>>>> } >>>>> >>>>> - ret = vfio_get_device(group, name, vbasedev, errp); >>>>> + ret = vfio_attach_device(name, vbasedev, >>>>> + pci_device_iommu_address_space(pdev), errp); >>>>> g_free(name); >>>>> if (ret) { >>>>> - vfio_put_group(group); >>>> independently on this patch, I think in case of error we leak >>>> vbasedev->name. Please have a look and if confirmed you can send a >>>> separate patch. >>> In case of error, vbasedev->name is freed in vfio_put_device(). >> called in vfio_instance_finalize only. See comment below >>>> Also I think if any subsequent action fail we shoudl properly detach the >>>> detach the device so introduce an extra error goto label, my bad sorry. >>> vfio_detach_device is called in vfio_instance_finalize(), this is just to follow >>> the old code, group and container resource allocated in vfio_realize() are >>> freed in vfio_instance_finalize(). >>> >>> I agree this is strange, but I guess there may be some reason I'm unclear. >> Yeah but if vfio_realize does fail, I am not sure the >> vfio_instance_finalize gets called > If vfio_realize fails, fio_exitfn() will not be called but vfio_instance_finalize will. > Note vfio_instance_finalize() is called by object_unref(). ah OK that's what I forgot then :-( Eric > > Thanks > Zhenzhong >