Messages in this thread | | | Subject | Re: [PATCH v7 1/5] vfio/migration: Add debugfs to live migration driver | From | liulongfang <> | Date | Wed, 1 Feb 2023 11:20:08 +0800 |
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On 2023/1/27 3:27, Alex Williamson wrote: > On Fri, 20 Jan 2023 11:29:26 +0800 > Longfang Liu <liulongfang@huawei.com> wrote: > >> There are multiple devices, software and operational steps involved >> in the process of live migration. An error occurred on any node may >> cause the live migration operation to fail. >> This complex process makes it very difficult to locate and analyze >> the cause when the function fails. >> >> In order to quickly locate the cause of the problem when the >> live migration fails, I added a set of debugfs to the vfio >> live migration driver. >> >> +------------------------------------------+ >> | | >> | | >> | QEMU | >> | | >> | | >> +-----+-------------------------+----------+ >> | ^ | ^ >> v | v | >> +-----+--+ +-----+--+ >> | src VF | | dst VF | >> +-+------+ +-+------+ >> | ^ | ^ >> v | v | >> +-------+-+------+ +-------+-+------+ >> |Debugfs|state | |Debugfs|state | >> +-------+--------+ +-------+--------+ >> | debug_root | | debug_root | >> +-------+--------+ +-------+--------+ >> >> The entire debugfs directory will be based on the definition of >> the CONFIG_DEBUG_FS macro. If this macro is not enabled, the >> interfaces in vfio_pci_debugfs.h will be empty definitions, >> and the creation and initialization of the debugfs directory >> will not be executed. >> >> debugfs will create a public root directory "vfio_mig" file. >> then create a "debug_root" file for each live migration VF device. > > s/VF // In practice it may be VFs, but I don't think we want to > artificially imply that the device must be a VF. In fact, I'm not sure
Yes, the description should be modified here, and it should not be limited to only support VF.
> why any of this code lives in vfio/pci/ vs vfio/, there's nothing PCI > specific here. Why isn't all of this done in vfio_main to be shared > with both pci and non-pci vfio drivers and devices? >
Combined with your observations below, I think it is more appropriate to create a "vfio-pci" directory here, because the current live migration function is still used on pci devices.
For non-pci devices, if there is a device that needs to add debugfs, then it can create a similar directory.
>> state file: used to get the status of the live migration device. >> debug_root: used to create your own custom debug files for live >> migration device drivers. >> >> The live migration function of the current device can be tested by >> operating the debug files, and the functional status of the equipment >> and software at each stage can be tested step by step without >> performing the complete live migration function. And after the live >> migration is performed, the migration device data of the live migration >> can be obtained through the debug files. >> >> Signed-off-by: Longfang Liu <liulongfang@huawei.com> >> --- >> drivers/vfio/pci/Makefile | 1 + >> drivers/vfio/pci/vfio_pci_core.c | 3 ++ >> drivers/vfio/pci/vfio_pci_debugfs.c | 80 +++++++++++++++++++++++++++++ >> drivers/vfio/pci/vfio_pci_debugfs.h | 28 ++++++++++ >> include/linux/vfio.h | 8 +++ >> 5 files changed, 120 insertions(+) >> create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.c >> create mode 100644 drivers/vfio/pci/vfio_pci_debugfs.h >> >> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile >> index 24c524224da5..75fe37e72e8d 100644 >> --- a/drivers/vfio/pci/Makefile >> +++ b/drivers/vfio/pci/Makefile >> @@ -2,6 +2,7 @@ >> >> vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o >> vfio-pci-core-$(CONFIG_VFIO_PCI_ZDEV_KVM) += vfio_pci_zdev.o >> +vfio-pci-core-$(CONFIG_DEBUG_FS) += vfio_pci_debugfs.o >> obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o >> >> vfio-pci-y := vfio_pci.o >> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c >> index f9365a5bc961..e85df2deb8e6 100644 >> --- a/drivers/vfio/pci/vfio_pci_core.c >> +++ b/drivers/vfio/pci/vfio_pci_core.c >> @@ -31,6 +31,7 @@ >> #include <asm/eeh.h> >> #endif >> >> +#include "vfio_pci_debugfs.h" >> #include "vfio_pci_priv.h" >> >> #define DRIVER_AUTHOR "Alex Williamson <alex.williamson@redhat.com>" >> @@ -2555,11 +2556,13 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_set_params); >> >> static void vfio_pci_core_cleanup(void) >> { >> + vfio_pci_debugfs_remove_root(); >> vfio_pci_uninit_perm_bits(); >> } >> >> static int __init vfio_pci_core_init(void) >> { >> + vfio_pci_debugfs_create_root(); >> /* Allocate shared config space permission data used by all devices */ >> return vfio_pci_init_perm_bits(); >> } >> diff --git a/drivers/vfio/pci/vfio_pci_debugfs.c b/drivers/vfio/pci/vfio_pci_debugfs.c >> new file mode 100644 >> index 000000000000..0bcf0bf034e5 >> --- /dev/null >> +++ b/drivers/vfio/pci/vfio_pci_debugfs.c >> @@ -0,0 +1,80 @@ >> +// SPDX-License-Identifier: GPL-2.0-only >> +/* >> + * Copyright (c) 2023, HiSilicon Ltd. >> + */ >> + >> +#include <linux/pci.h> >> +#include <linux/vfio_pci_core.h> >> + >> +#include "vfio_pci_debugfs.h" >> + >> +static struct dentry *vfio_pci_debugfs_root; >> + >> +static int vfio_pci_vf_state_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; >> + enum vfio_device_mig_state state; >> + int ret; >> + >> + ret = vdev->mig_ops->migration_get_state(vdev, &state); >> + if (ret) >> + return -EINVAL; >> + >> + switch (state) { >> + case VFIO_DEVICE_STATE_RUNNING: >> + seq_printf(seq, "%s\n", "RUNNING"); >> + break; >> + case VFIO_DEVICE_STATE_STOP_COPY: >> + seq_printf(seq, "%s\n", "STOP_COPY"); >> + break; >> + case VFIO_DEVICE_STATE_STOP: >> + seq_printf(seq, "%s\n", "STOP"); >> + break; >> + case VFIO_DEVICE_STATE_RESUMING: >> + seq_printf(seq, "%s\n", "RESUMING"); >> + break; >> + case VFIO_DEVICE_STATE_RUNNING_P2P: >> + seq_printf(seq, "%s\n", "RESUMING_P2P"); >> + break; >> + case VFIO_DEVICE_STATE_ERROR: >> + seq_printf(seq, "%s\n", "ERROR"); >> + break; >> + default: >> + seq_printf(seq, "%s\n", "Invalid"); >> + } >> + >> + return 0; >> +} >> + >> +void vfio_pci_vf_debugfs_init(struct vfio_device *vdev) >> +{ >> + struct device *dev = vdev->dev; >> + >> + vdev->debug_root = debugfs_create_dir(dev_name(dev), vfio_pci_debugfs_root); >> + >> + debugfs_create_devm_seqfile(dev, "state", vdev->debug_root, >> + vfio_pci_vf_state_read); >> +} >> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_init); >> + >> +void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev) >> +{ >> + debugfs_remove_recursive(vdev->debug_root); >> +} >> +EXPORT_SYMBOL_GPL(vfio_pci_vf_debugfs_exit); >> + >> +void vfio_pci_debugfs_create_root(void) >> +{ >> + vfio_pci_debugfs_root = debugfs_create_dir("vfio_mig", NULL); > > Is this hierarchical, ie. should we have "vfio/migration/" such that we > can introduce other debugfs entries w/o creating vfio_foo, vfio_bar, > vfio_baz, etc. Otherwise the core or pci-core should only initialize a > "vfio" or "vfio-pci" root and the above init and exit interfaces should > be migration specific, creating "migrations_state" and only removing > the entries on exit that their companion init function created. >
Yes, your suggestion is very good. Here I also agree to create a "vfio-pci" directory.In addition, it is not easy to create a "migration" subdirectory internally,because there is no valid basis for judging whether to create a "migration" directory when creating a vfio-pci directory. Therefore, it is simpler to create migration_state directly with migration as a prefix.
>> +} >> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_create_root); >> + >> +void vfio_pci_debugfs_remove_root(void) >> +{ >> + debugfs_remove_recursive(vfio_pci_debugfs_root); >> + vfio_pci_debugfs_root = NULL; >> +} >> +EXPORT_SYMBOL_GPL(vfio_pci_debugfs_remove_root); >> + >> diff --git a/drivers/vfio/pci/vfio_pci_debugfs.h b/drivers/vfio/pci/vfio_pci_debugfs.h >> new file mode 100644 >> index 000000000000..beaaa709725e >> --- /dev/null >> +++ b/drivers/vfio/pci/vfio_pci_debugfs.h >> @@ -0,0 +1,28 @@ >> +/* SPDX-License-Identifier: GPL-2.0 */ >> +/* >> + * vfio_pci_debugfs.h - VFIO migration debugfs interface >> + * >> + * Copyright (c) 2023, HiSilicon Ltd. >> + * >> + * Author: Longfang Liu <liulongfang@huawei.com> >> + */ >> + >> +#ifndef __VFIO_PCI_DEBUGFS_H >> +#define __VFIO_PCI_DEBUGFS_H >> + >> +#include <linux/debugfs.h> >> +#include <linux/vfio.h> >> + >> +#ifdef CONFIG_DEBUG_FS >> +void vfio_pci_debugfs_create_root(void); >> +void vfio_pci_debugfs_remove_root(void); >> +void vfio_pci_vf_debugfs_init(struct vfio_device *vdev); >> +void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev); >> +#else >> +static inline void vfio_pci_debugfs_create_root(void) {} >> +static inline void vfio_pci_debugfs_remove_root(void) {} >> +static inline void vfio_pci_vf_debugfs_init(struct vfio_device *vdev) {} >> +static inline void vfio_pci_vf_debugfs_exit(struct vfio_device *vdev) {} >> +#endif /* CONFIG_DEBUG_FS */ >> + >> +#endif /* __VFIO_PCI_DEBUGFS_H */ > > With the above changes, declarations should probably just exist in > drivers/vfio/vfio.h. Thanks, >
Ok, then I'll delete this header file and put them directly in vfio.h
> Alex > Thanks, Longfang.
>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h >> index b4d5d4ca3d7d..b4bc8dfe8413 100644 >> --- a/include/linux/vfio.h >> +++ b/include/linux/vfio.h >> @@ -54,6 +54,14 @@ struct vfio_device { >> struct completion comp; >> struct list_head group_next; >> struct list_head iommu_entry; >> + >> +#ifdef CONFIG_DEBUG_FS >> + /* >> + * debug_root is a static property of the vfio_device >> + * which must be set prior to registering the vfio_device. >> + */ >> + struct dentry *debug_root; >> +#endif >> }; >> >> /** > > . >
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