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    SubjectRe: [PATCH v11 3/4] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver
    On Fri, 30 Jun 2023 17:24:56 +0800
    liulongfang <liulongfang@huawei.com> wrote:

    > From: Longfang Liu <liulongfang@huawei.com>
    >
    > On the debugfs framework of VFIO, if the CONFIG_DEBUG_FS 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:
    >
    > 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.
    > io_test: used to test IO read and write for the driver.
    >
    > Signed-off-by: Longfang Liu <liulongfang@huawei.com>
    > ---
    > .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c | 182 ++++++++++++++++++
    > .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 11 ++
    > 2 files changed, 193 insertions(+)
    >
    > diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
    > index a1589947e721..a6f5e94bfaf2 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)
    > @@ -606,6 +607,18 @@ 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 *src_migf,
    > + struct hisi_acc_vf_migration_file *dst_migf)

    Consider swapping the args to be more consistent with functions like
    memcpy() where the destination is the first arg and source is the
    second.

    > +{
    > + 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);
    > @@ -618,12 +631,16 @@ 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->resuming_migf,
    > + hisi_acc_vdev->debug_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->saving_migf,
    > + hisi_acc_vdev->debug_migf);
    > hisi_acc_vf_disable_fd(hisi_acc_vdev->saving_migf);
    > fput(hisi_acc_vdev->saving_migf->filp);
    > hisi_acc_vdev->saving_migf = NULL;
    > @@ -1303,6 +1320,164 @@ 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 not support debugfs!");

    "device does not support debugfs"?

    > + return -EINVAL;
    > + }
    > +
    > + /* If device not opened, the debugfs operation will trigger calltrace */
    > + if (!vdev->open_count) {
    > + seq_printf(seq, "%s\n", "device not opened!");
    > + return -EINVAL;
    > + }

    What prevents this from racing release of the device?

    > +
    > + return 0;
    > +}
    > +
    > +static int hisi_acc_vf_debug_io(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;

    A tab sneaked in here.

    > + 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)
    > + goto io_err;
    > +
    > + ret = qm_wait_dev_not_ready(vf_qm);
    > + if (ret) {
    > + seq_printf(seq, "%s\n", "VF device not ready!");
    > + goto io_err;
    > + }
    > +
    > + value = readl(vf_qm->io_base + QM_MB_CMD_SEND_BASE);
    > + seq_printf(seq, "%s:0x%llx\n", "debug mailbox val", value);
    > +
    > +io_err:
    > + return 0;

    A goto that simply returns seems unnecessary vs return at the error
    condition. Also why don't we return the errno for error cases? Do we
    even need seq_printf() calls for error cases?

    > +}
    > +
    > +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;

    Another tab.

    > + 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)
    > + goto save_err;
    > +
    > + ret = vf_qm_state_save(hisi_acc_vdev, migf);
    > + if (ret) {
    > + seq_printf(seq, "%s\n", "failed to save device data!");
    > + goto save_err;
    > + }
    > + seq_printf(seq, "%s\n", "successful to save device data!");
    > +
    > +save_err:
    > + 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;

    Tab.

    > + 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;

    Tab.

    > + 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) {
    > + 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, "io_test", vfio_hisi_acc,
    > + hisi_acc_vf_debug_io);
    > + 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);
    > @@ -1323,6 +1498,7 @@ static int hisi_acc_vfio_pci_open_device(struct vfio_device *core_vdev)
    > }
    >
    > vfio_pci_core_finish_enable(vdev);
    > +
    > return 0;
    > }
    >
    > @@ -1420,9 +1596,14 @@ 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:
    > + if (ops == &hisi_acc_vfio_pci_migrn_ops)
    > + hisi_acc_vf_debugfs_exit(hisi_acc_vdev);

    Why do we need this? There's no case where debug_init occurs before
    this goto.

    > vfio_put_device(&hisi_acc_vdev->core_device.vdev);
    > return ret;
    > }
    > @@ -1431,6 +1612,7 @@ static void hisi_acc_vfio_pci_remove(struct pci_dev *pdev)
    > {
    > struct hisi_acc_vf_core_device *hisi_acc_vdev = hisi_acc_drvdata(pdev);
    >
    > + hisi_acc_vf_debugfs_exit(hisi_acc_vdev);
    > vfio_pci_core_unregister_device(&hisi_acc_vdev->core_device);
    > 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 dcabfeec6ca1..ef50b12f018d 100644
    > --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
    > +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
    > @@ -49,6 +49,14 @@
    > #define QM_EQC_DW0 0X8000
    > #define QM_AEQC_DW0 0X8020
    >
    > +#define VFIO_DEV_DBG_LEN 256
    > +
    > +enum mig_debug_cmd {
    > + STATE_SAVE,
    > + STATE_RESUME,
    > + RW_IO_TEST,
    > +};

    Unused.

    Thanks,
    Alex

    > +
    > struct acc_vf_data {
    > #define QM_MATCH_SIZE offsetofend(struct acc_vf_data, qm_rsv_state)
    > /* QM match information */
    > @@ -113,5 +121,8 @@ 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;
    > +
    > + /* For debugfs */
    > + struct hisi_acc_vf_migration_file *debug_migf;
    > };
    > #endif /* HISI_ACC_VFIO_PCI_H */

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