On Thu, 25 Jan 2024 16:10:30 +0800
Longfang Liu <liulongfang@xxxxxxxxxx> 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
> |
> +---<dev_name1>
> | +---migration
> | +--state
> | +--hisi_acc
> | +--attr
> | +--data
> | +--save
> | +--cmd_state
> |
> +---<dev_name2>
> +---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 <liulongfang@xxxxxxxxxx>
> ---
> .../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 <linux/anon_inodes.h>
>
> #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.
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,
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 */
