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Sun, 28 Jan 2024 18:37:25 -0800 (PST) X-Google-Smtp-Source: AGHT+IGL4U+CjALkUwgvEr0R2oxBdMRVvvqiairWp4q2asmJLUfMC7QmBMQd0rY+7cfLFiD2FCE7LA== X-Received: by 2002:a92:ce52:0:b0:363:7777:658f with SMTP id a18-20020a92ce52000000b003637777658fmr3539021ilr.11.1706495845142; Sun, 28 Jan 2024 18:37:25 -0800 (PST) Received: from redhat.com ([38.15.36.11]) by smtp.gmail.com with ESMTPSA id n12-20020a92d9cc000000b0036382484384sm275669ilq.17.2024.01.28.18.37.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 28 Jan 2024 18:37:24 -0800 (PST) Date: Sun, 28 Jan 2024 19:37:23 -0700 From: Alex Williamson To: liulongfang Cc: , , , , , Subject: Re: [PATCH 2/3] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver Message-ID: <20240128193723.2f16c2fc.alex.williamson@redhat.com> In-Reply-To: References: <20240125081031.48707-1-liulongfang@huawei.com> <20240125081031.48707-3-liulongfang@huawei.com> <20240125153834.3f44bbad.alex.williamson@redhat.com> Organization: Red Hat Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 29 Jan 2024 10:24:00 +0800 liulongfang wrote: > On 2024/1/26 6:38, Alex Williamson wrote: > > On Thu, 25 Jan 2024 16:10:30 +0800 > > Longfang Liu wrote: > > > >> On the debugfs framework of VFIO, if the CONFIG_VFIO_DEBUGFS macro is > >> enabled, the debug function is registered for the live migration driver > >> of the HiSilicon accelerator device. > >> > >> After registering the HiSilicon accelerator device on the debugfs > >> framework of live migration of vfio, a directory file "hisi_acc" > >> of debugfs is created, and then three debug function files are > >> created in this directory: > >> > >> vfio > >> | > >> +--- > >> | +---migration > >> | +--state > >> | +--hisi_acc > >> | +--attr > >> | +--data > >> | +--save > >> | +--cmd_state > >> | > >> +--- > >> +---migration > >> +--state > >> +--hisi_acc > >> +--attr > >> +--data > >> +--save > >> +--cmd_state > >> > >> data file: used to get the migration data from the driver > >> attr file: used to get device attributes parameters from the driver > >> save file: used to read the data of the live migration device and save > >> it to the driver. > >> cmd_state: used to get the cmd channel state for the device. > >> > >> Signed-off-by: Longfang Liu > >> --- > >> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 190 ++++++++++++++++++ > >> .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 5 + > >> 2 files changed, 195 insertions(+) > >> > >> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c > >> index 5f6e01571a7b..2cbbc52b7377 100644 > >> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c > >> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c > >> @@ -15,6 +15,7 @@ > >> #include > >> > >> #include "hisi_acc_vfio_pci.h" > >> +#include "../../vfio.h" > >> > >> /* Return 0 on VM acc device ready, -ETIMEDOUT hardware timeout */ > >> static int qm_wait_dev_not_ready(struct hisi_qm *qm) > >> @@ -617,6 +618,18 @@ hisi_acc_check_int_state(struct hisi_acc_vf_core_device *hisi_acc_vdev) > >> } > >> } > >> > >> +static void hisi_acc_vf_migf_save(struct hisi_acc_vf_migration_file *dst_migf, > >> + struct hisi_acc_vf_migration_file *src_migf) > >> +{ > >> + if (!dst_migf) > >> + return; > >> + > >> + dst_migf->disabled = false; > >> + dst_migf->total_length = src_migf->total_length; > >> + memcpy(&dst_migf->vf_data, &src_migf->vf_data, > >> + sizeof(struct acc_vf_data)); > >> +} > >> + > >> static void hisi_acc_vf_disable_fd(struct hisi_acc_vf_migration_file *migf) > >> { > >> mutex_lock(&migf->lock); > >> @@ -629,12 +642,16 @@ static void hisi_acc_vf_disable_fd(struct hisi_acc_vf_migration_file *migf) > >> static void hisi_acc_vf_disable_fds(struct hisi_acc_vf_core_device *hisi_acc_vdev) > >> { > >> if (hisi_acc_vdev->resuming_migf) { > >> + hisi_acc_vf_migf_save(hisi_acc_vdev->debug_migf, > >> + hisi_acc_vdev->resuming_migf); > >> hisi_acc_vf_disable_fd(hisi_acc_vdev->resuming_migf); > >> fput(hisi_acc_vdev->resuming_migf->filp); > >> hisi_acc_vdev->resuming_migf = NULL; > >> } > >> > >> if (hisi_acc_vdev->saving_migf) { > >> + hisi_acc_vf_migf_save(hisi_acc_vdev->debug_migf, > >> + hisi_acc_vdev->saving_migf); > >> hisi_acc_vf_disable_fd(hisi_acc_vdev->saving_migf); > >> fput(hisi_acc_vdev->saving_migf->filp); > >> hisi_acc_vdev->saving_migf = NULL; > >> @@ -1175,6 +1192,7 @@ static int hisi_acc_vf_qm_init(struct hisi_acc_vf_core_device *hisi_acc_vdev) > >> if (!vf_qm->io_base) > >> return -EIO; > >> > >> + mutex_init(&hisi_acc_vdev->enable_mutex); > >> vf_qm->fun_type = QM_HW_VF; > >> vf_qm->pdev = vf_dev; > >> mutex_init(&vf_qm->mailbox_lock); > >> @@ -1325,6 +1343,172 @@ static long hisi_acc_vfio_pci_ioctl(struct vfio_device *core_vdev, unsigned int > >> return vfio_pci_core_ioctl(core_vdev, cmd, arg); > >> } > >> > >> +static int hisi_acc_vf_debug_check(struct seq_file *seq, struct vfio_device *vdev) > >> +{ > >> + struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev); > >> + struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf; > >> + > >> + if (!vdev->mig_ops || !migf) { > >> + seq_printf(seq, "%s\n", "device does not support live migration!"); > >> + return -EINVAL; > >> + } > >> + > >> + /** > >> + * When the device is not opened, the io_base is not mapped. > >> + * The driver cannot perform device read and write operations. > >> + */ > >> + if (!vdev->open_count) { > >> + seq_printf(seq, "%s\n", "device not opened!"); > >> + return -EINVAL; > >> + } > > > > This is racy, this check could occur while the user is already closing > > the device and vfio_df_device_last_close() may have already iounmap'd > > the io_base. Only after that is open_count decremented. The debugfs > > interfaces would then proceed to access the unmapped space. The > > enable_mutex is entirely ineffective (and also asymmetric, initialized > > in the open_device path but never destroyed). > > > > In fact, the enable_mutex really only seems to be trying to protect > > io_base (which it doesn't do), meanwhile the core driver execution path > > can run concurrently to debugfs operations with no serialization. It > > looks like these operations would step on each other. > > > > Yes, this enable_mutex is used to protect io_base. It prevents debugfs > from being used after executing iounmap in io_base. > > > I think you might need an atomic to guard against io_base unmapping and > > then maybe a mutex or semaphore to avoid debugfs accesses from > > interfering with the actual core logic interacting with the device. > > Thanks, > > > > OK An atomic variable needs to be added to replace vdev->open_count to prevent > competition. And use enable_mutex to prevent io_base from being released early. That's not what I'm suggesting, open_count is safe in the core code, it doesn't need to be an atomic. Your use of it is unsafe. enable_mutex doesn't protect what it intends to protect. Thanks, Alex > >> + return 0; > >> +} > >> + > >> +static int hisi_acc_vf_debug_cmd(struct seq_file *seq, void *data) > >> +{ > >> + struct device *vf_dev = seq->private; > >> + struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev); > >> + struct vfio_device *vdev = &core_device->vdev; > >> + struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev); > >> + struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm; > >> + u64 value; > >> + int ret; > >> + > >> + ret = hisi_acc_vf_debug_check(seq, vdev); > >> + if (ret) > >> + return 0; > >> + > >> + mutex_lock(&hisi_acc_vdev->enable_mutex); > >> + ret = qm_wait_dev_not_ready(vf_qm); > >> + if (ret) { > >> + mutex_unlock(&hisi_acc_vdev->enable_mutex); > >> + seq_printf(seq, "%s\n", "VF device not ready!"); > >> + return 0; > >> + } > >> + > >> + value = readl(vf_qm->io_base + QM_MB_CMD_SEND_BASE); > >> + mutex_unlock(&hisi_acc_vdev->enable_mutex); > >> + seq_printf(seq, "%s:0x%llx\n", "mailbox cmd channel state is OK", value); > >> + > >> + return 0; > >> +} > >> + > >> +static int hisi_acc_vf_debug_save(struct seq_file *seq, void *data) > >> +{ > >> + struct device *vf_dev = seq->private; > >> + struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev); > >> + struct vfio_device *vdev = &core_device->vdev; > >> + struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev); > >> + struct hisi_acc_vf_migration_file *migf = hisi_acc_vdev->debug_migf; > >> + int ret; > >> + > >> + ret = hisi_acc_vf_debug_check(seq, vdev); > >> + if (ret) > >> + return 0; > >> + > >> + mutex_lock(&hisi_acc_vdev->enable_mutex); > >> + ret = vf_qm_state_save(hisi_acc_vdev, migf); > >> + if (ret) { > >> + mutex_unlock(&hisi_acc_vdev->enable_mutex); > >> + seq_printf(seq, "%s\n", "failed to save device data!"); > >> + return 0; > >> + } > >> + mutex_unlock(&hisi_acc_vdev->enable_mutex); > >> + seq_printf(seq, "%s\n", "successful to save device data!"); > >> + > >> + return 0; > >> +} > >> + > >> +static int hisi_acc_vf_data_read(struct seq_file *seq, void *data) > >> +{ > >> + struct device *vf_dev = seq->private; > >> + struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev); > >> + struct vfio_device *vdev = &core_device->vdev; > >> + struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev); > >> + struct hisi_acc_vf_migration_file *debug_migf = hisi_acc_vdev->debug_migf; > >> + size_t vf_data_sz = offsetofend(struct acc_vf_data, padding); > >> + > >> + if (debug_migf && debug_migf->total_length) > >> + seq_hex_dump(seq, "Mig Data:", DUMP_PREFIX_OFFSET, 16, 1, > >> + (unsigned char *)&debug_migf->vf_data, > >> + vf_data_sz, false); > >> + else > >> + seq_printf(seq, "%s\n", "device not migrated!"); > >> + > >> + return 0; > >> +} > >> + > >> +static int hisi_acc_vf_attr_read(struct seq_file *seq, void *data) > >> +{ > >> + struct device *vf_dev = seq->private; > >> + struct vfio_pci_core_device *core_device = dev_get_drvdata(vf_dev); > >> + struct vfio_device *vdev = &core_device->vdev; > >> + struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(vdev); > >> + struct hisi_acc_vf_migration_file *debug_migf = hisi_acc_vdev->debug_migf; > >> + > >> + if (debug_migf && debug_migf->total_length) { > >> + seq_printf(seq, > >> + "acc device:\n" > >> + "device state: %d\n" > >> + "device ready: %u\n" > >> + "data valid: %d\n" > >> + "data size: %lu\n", > >> + hisi_acc_vdev->mig_state, > >> + hisi_acc_vdev->vf_qm_state, > >> + debug_migf->disabled, > >> + debug_migf->total_length); > >> + } else { > >> + seq_printf(seq, "%s\n", "device not migrated!"); > >> + } > >> + > >> + return 0; > >> +} > >> + > >> +static int hisi_acc_vfio_debug_init(struct hisi_acc_vf_core_device *hisi_acc_vdev) > >> +{ > >> + struct vfio_device *vdev = &hisi_acc_vdev->core_device.vdev; > >> + struct dentry *vfio_dev_migration = NULL; > >> + struct dentry *vfio_hisi_acc = NULL; > >> + struct device *dev = vdev->dev; > >> + void *migf = NULL; > >> + > >> + if (!debugfs_initialized()) > >> + return 0; > >> + > >> + migf = kzalloc(sizeof(struct hisi_acc_vf_migration_file), GFP_KERNEL); > >> + if (!migf) > >> + return -ENOMEM; > >> + hisi_acc_vdev->debug_migf = migf; > >> + > >> + vfio_dev_migration = debugfs_lookup("migration", vdev->debug_root); > >> + if (!vfio_dev_migration) { > >> + kfree(migf); > >> + dev_err(dev, "failed to lookup migration debugfs file!\n"); > >> + return -ENODEV; > >> + } > >> + > >> + vfio_hisi_acc = debugfs_create_dir("hisi_acc", vfio_dev_migration); > >> + debugfs_create_devm_seqfile(dev, "data", vfio_hisi_acc, > >> + hisi_acc_vf_data_read); > >> + debugfs_create_devm_seqfile(dev, "attr", vfio_hisi_acc, > >> + hisi_acc_vf_attr_read); > >> + debugfs_create_devm_seqfile(dev, "cmd_state", vfio_hisi_acc, > >> + hisi_acc_vf_debug_cmd); > >> + debugfs_create_devm_seqfile(dev, "save", vfio_hisi_acc, > >> + hisi_acc_vf_debug_save); > >> + > >> + return 0; > >> +} > >> + > >> +static void hisi_acc_vf_debugfs_exit(struct hisi_acc_vf_core_device *hisi_acc_vdev) > >> +{ > >> + if (!debugfs_initialized()) > >> + return; > >> + > >> + kfree(hisi_acc_vdev->debug_migf); > >> +} > >> + > >> static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev) > >> { > >> struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev); > >> @@ -1353,7 +1537,9 @@ static void hisi_acc_vfio_pci_close_device(struct vfio_device *core_vdev) > >> struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_get_vf_dev(core_vdev); > >> struct hisi_qm *vf_qm = &hisi_acc_vdev->vf_qm; > >> > >> + mutex_lock(&hisi_acc_vdev->enable_mutex); > >> iounmap(vf_qm->io_base); > >> + mutex_unlock(&hisi_acc_vdev->enable_mutex); > >> vfio_pci_core_close_device(core_vdev); > >> } > >> > >> @@ -1444,6 +1630,9 @@ static int hisi_acc_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device > >> ret = vfio_pci_core_register_device(&hisi_acc_vdev->core_device); > >> if (ret) > >> goto out_put_vdev; > >> + > >> + if (ops == &hisi_acc_vfio_pci_migrn_ops) > >> + hisi_acc_vfio_debug_init(hisi_acc_vdev); > >> return 0; > >> > >> out_put_vdev: > >> @@ -1456,6 +1645,7 @@ static void hisi_acc_vfio_pci_remove(struct pci_dev *pdev) > >> struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev); > >> > >> vfio_pci_core_unregister_device(&hisi_acc_vdev->core_device); > >> + hisi_acc_vf_debugfs_exit(hisi_acc_vdev); > >> vfio_put_device(&hisi_acc_vdev->core_device.vdev); > >> } > >> > >> diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h > >> index c58fc5861492..38327b97d535 100644 > >> --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h > >> +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h > >> @@ -116,5 +116,10 @@ struct hisi_acc_vf_core_device { > >> spinlock_t reset_lock; > >> struct hisi_acc_vf_migration_file *resuming_migf; > >> struct hisi_acc_vf_migration_file *saving_migf; > >> + > >> + /* To make sure the device is enabled */ > >> + struct mutex enable_mutex; > >> + /* For debugfs */ > >> + struct hisi_acc_vf_migration_file *debug_migf; > >> }; > >> #endif /* HISI_ACC_VFIO_PCI_H */ > > > > . > > >