Re: [PATCH v2 2/3] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver

From: Alex Williamson
Date: Mon Feb 05 2024 - 18:16:03 EST

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On Mon, 5 Feb 2024 08:52:06 +0000
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> wrote:

> > -----Original Message-----
> > From: liulongfang <liulongfang@xxxxxxxxxx>
> > Sent: Sunday, February 4, 2024 8:56 AM
> > To: alex.williamson@xxxxxxxxxx; jgg@xxxxxxxxxx; Shameerali Kolothum
> > Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>; Jonathan Cameron
> > <jonathan.cameron@xxxxxxxxxx>
> > Cc: kvm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > linuxarm@xxxxxxxxxxxxx; liulongfang <liulongfang@xxxxxxxxxx>
> > Subject: [PATCH v2 2/3] hisi_acc_vfio_pci: register debugfs for hisilicon
> > migration driver
> >
> > 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 | 197 ++++++++++++++++++
> > .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h | 11 +
> > 2 files changed, 208 insertions(+)
> >
> > diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> > b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
> > index 00a22a990eb8..e51bbb41c2b3 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
> > *dst_migf,
>
> Can we please rename this to indicate the debug, similar to other debugfs support
> functions here, something like hisi_acc_vf_debug_migf_save()?
>
> > + struct hisi_acc_vf_migration_file *src_migf)
> > +{
> > + if (!dst_migf)
> > + return;
> > +
> > + dst_migf->disabled = false;
>
> Is this set to true anywhere for debugfs migf ?
>
> > + 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->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;
> > @@ -1156,6 +1173,7 @@ 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);
> > @@ -1306,6 +1324,176 @@ 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 (atomic_read(&hisi_acc_vdev->dev_opened) != DEV_OPEN) {
> > + seq_printf(seq, "%s\n", "device not opened!");
> > + return -EINVAL;
> > + }
> > +
> > + 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;
> > +
> > + mutex_lock(&hisi_acc_vdev->enable_mutex);
> > + ret = hisi_acc_vf_debug_check(seq, vdev);
> > + if (ret) {
> > + mutex_unlock(&hisi_acc_vdev->enable_mutex);
> > + return 0;
> > + }
> > +
> > + 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;
> > +
> > + mutex_lock(&hisi_acc_vdev->enable_mutex);
> > + ret = hisi_acc_vf_debug_check(seq, vdev);
> > + if (ret) {
> > + mutex_unlock(&hisi_acc_vdev->enable_mutex);
> > + return 0;
> > + }
> > +
> > + ret = vf_qm_state_save(hisi_acc_vdev, migf);
>
> Are you sure this will not interfere with the core migration APIs as we are not
> holding the state_mutex?. I think Alex also raised a similar concern previously.
> Applies to other debugfs interfaces here as well. Please check.

And if it does not need to be serialized, why are we using a mutex
rather than a semaphore? For example if it can run concurrently with
the core migration APIs, it should run concurrently with itself and
debugfs could take read-locks. Also as implemented here the atomic is
not only uninitialized, but pretty pointless anyway. dev_opened could
be a bool protected within the mutex/semaphore, which would at least
make it sane that the lock protects the bool since it clearly doesn't
protect io_base. Thanks,

Alex

> > + 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);
> > @@ -1323,9 +1511,11 @@ static int hisi_acc_vfio_pci_open_device(struct
> > vfio_device *core_vdev)
> > return ret;
> > }
> > hisi_acc_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
> > + atomic_set(&hisi_acc_vdev->dev_opened, DEV_OPEN);
> > }
> >
> > vfio_pci_core_finish_enable(vdev);
> > +
> > return 0;
> > }
> >
> > @@ -1334,7 +1524,10 @@ 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;
> >
> > + atomic_set(&hisi_acc_vdev->dev_opened, DEV_CLOSE);
> > + 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);
> > }
> >
> > @@ -1425,6 +1618,9 @@ 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:
> > @@ -1437,6 +1633,7 @@ 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 dcabfeec6ca1..283bd8acdc42 100644
> > --- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> > +++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.h
> > @@ -49,6 +49,11 @@
> > #define QM_EQC_DW0 0X8000
> > #define QM_AEQC_DW0 0X8020
> >
> > +enum acc_dev_state {
> > + DEV_CLOSE = 0x0,
> > + DEV_OPEN,
> > +};
>
> Do we really need this enum as you can directly use 0 or 1?
>
> Thanks,
> Shameer
>
> > +
> > struct acc_vf_data {
> > #define QM_MATCH_SIZE offsetofend(struct acc_vf_data, qm_rsv_state)
> > /* QM match information */
> > @@ -113,5 +118,11 @@ 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;
> > + atomic_t dev_opened;
> > + /* For debugfs */
> > + struct hisi_acc_vf_migration_file *debug_migf;
> > };
> > #endif /* HISI_ACC_VFIO_PCI_H */
> > --
> > 2.24.0
>
>

Next message: Dave Chinner: "Re: [PATCH] fs/address_space: move i_mmap_rwsem to mitigate a false sharing with i_mmap."
Previous message: Bjorn Helgaas: "Re: [PATCH v2 1/4] PCI/AER: Store more information in aer_err_info"
In reply to: Shameerali Kolothum Thodi: "RE: [PATCH v2 2/3] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver"
Next in thread: Longfang Liu: "[PATCH v2 3/3] Documentation: add debugfs description for hisi migration"
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