Re: [PATCH v6 4/5] hisi_acc_vfio_pci: register debugfs for hisilicon migration driver - Linuxarm

7 May 2024

...
-----Original Message-----
From: Alex Williamson alex.williamson@redhat.com
Sent: Friday, May 3, 2024 6:21 PM
To: liulongfang liulongfang@huawei.com
Cc: jgg@nvidia.com; Shameerali Kolothum Thodi
shameerali.kolothum.thodi@huawei.com; Jonathan Cameron
jonathan.cameron@huawei.com; kvm@vger.kernel.org; linux-
kernel@vger.kernel.org; linuxarm@openeuler.org
Subject: Re: [PATCH v6 4/5] hisi_acc_vfio_pci: register debugfs for hisilicon
migration driver
On Thu, 25 Apr 2024 21:23:21 +0800
Longfang Liu liulongfang@huawei.com 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
    |            +--dev_data
    |            +--migf_data
    |            +--cmd_state
    |
    +---<dev_name2>
         +---migration
             +--state
             +--hisi_acc
                 +--dev_data
                 +--migf_data
                 +--cmd_state
dev_data file: read device data that needs to be migrated from the
current device in real time
migf_data file: read the migration data of the last live migration
from the current driver.
cmd_state: used to get the cmd channel state for the device.
+----------------+        +--------------+       +---------------+
| migration dev  |        |   src  dev   |       |   dst  dev    |
+-------+--------+        +------+-------+       +-------+-------+
        |                        |                       |
        |                 +------v-------+       +-------v-------+
        |                 |  saving_mif  |       | resuming_migf |
  read  |                 |     file     |       |     file      |
        |                 +------+-------+       +-------+-------+
        |                        |          copy         |
        |                        +------------+----------+
        |                                     |
+-------v---------+                   +-------v--------+
|   data buffer   |                   |   debug_migf   |
+-------+---------+                   +-------+--------+
        |                                     |
   cat  |                                 cat |
+-------v--------+                    +-------v--------+
|   dev_data     |                    |   migf_data    |
+----------------+                    +----------------+
When accessing debugfs, user can obtain the real-time status data
of the device through the "dev_data" file. It will directly read
the device status data and will not affect the live migration
function. Its data is stored in the allocated memory buffer,
and the memory is released after data returning to user mode.
To obtain the data of the last complete migration, user need to
obtain it through the "migf_data" file. Since the live migration
data only exists during the migration process, it is destroyed
after the migration is completed.
In order to save this data, a debug_migf file is created in the
driver. At the end of the live migration process, copy the data
to debug_migf.
Signed-off-by: Longfang Liu liulongfang@huawei.com
.../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    | 225 ++++++++++++++++++
 .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h    |   7 +
 2 files changed, 232 insertions(+)

diff --git a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
...
index bf358ba94b5d..656b3d975940 100644
--- a/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
+++ b/drivers/vfio/pci/hisilicon/hisi_acc_vfio_pci.c
@@ -627,15 +627,33 @@ static void hisi_acc_vf_disable_fd(struct
hisi_acc_vf_migration_file *migf)
...
mutex_unlock(&migf->lock);
 }
+static void hisi_acc_debug_migf_copy(struct hisi_acc_vf_core_device
*hisi_acc_vdev,
...

struct hisi_acc_vf_migration_file *src_migf)

+{

struct hisi_acc_vf_migration_file *dst_migf = hisi_acc_vdev-

debug_migf;


if (!dst_migf)
return;



mutex_lock(&hisi_acc_vdev->enable_mutex);
dst_migf->disabled = src_migf->disabled;
dst_migf->total_length = src_migf->total_length;
memcpy(&dst_migf->vf_data, &src_migf->vf_data,
sizeof(struct acc_vf_data));


mutex_unlock(&hisi_acc_vdev->enable_mutex);

+}



static void hisi_acc_vf_disable_fds(struct hisi_acc_vf_core_device
*hisi_acc_vdev)
...
{
   if (hisi_acc_vdev->resuming_migf) {

hisi_acc_debug_migf_copy(hisi_acc_vdev, 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_debug_migf_copy(hisi_acc_vdev, 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;
@@ -1144,6 +1162,7 @@ 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);

@@ -1294,6 +1313,203 @@ 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_qm *vf_qm = &hisi_acc_vdev->vf_qm;
struct device *dev = vdev->dev;
int ret;

if (!vdev->mig_ops) {
dev_err(dev, "device does not support live migration!\n");



Sorry, every error path should not spam dmesg with dev_err().  I'm
going to wait until your co-maintainer approves this before looking at
any further iterations of this series.  Thanks,
Sure. I will sync up with Longfang and also make sure we address all the existing
comments on this before posting the next revision.
Thanks,
Shameer

    