|
From: | Kirti Wankhede |
Subject: | Re: [PATCH v26 07/17] vfio: Register SaveVMHandlers for VFIO device |
Date: | Sun, 18 Oct 2020 23:10:40 +0530 |
User-agent: | Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 |
On 9/26/2020 1:50 AM, Alex Williamson wrote:
On Wed, 23 Sep 2020 04:54:09 +0530 Kirti Wankhede <kwankhede@nvidia.com> wrote:Define flags to be used as delimeter in migration file stream. Added .save_setup and .save_cleanup functions. Mapped & unmapped migration region from these functions at source during saving or pre-copy phase. Set VFIO device state depending on VM's state. During live migration, VM is running when .save_setup is called, _SAVING | _RUNNING state is set for VFIO device. During save-restore, VM is paused, _SAVING state is set for VFIO device. Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> Reviewed-by: Neo Jia <cjia@nvidia.com> --- hw/vfio/migration.c | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++ hw/vfio/trace-events | 2 ++ 2 files changed, 93 insertions(+) diff --git a/hw/vfio/migration.c b/hw/vfio/migration.c index f650fe9fc3c8..8e8adaa25779 100644 --- a/hw/vfio/migration.c +++ b/hw/vfio/migration.c @@ -8,12 +8,15 @@ */#include "qemu/osdep.h"+#include "qemu/main-loop.h" +#include "qemu/cutils.h" #include <linux/vfio.h>#include "sysemu/runstate.h"#include "hw/vfio/vfio-common.h" #include "cpu.h" #include "migration/migration.h" +#include "migration/vmstate.h" #include "migration/qemu-file.h" #include "migration/register.h" #include "migration/blocker.h" @@ -25,6 +28,17 @@ #include "trace.h" #include "hw/hw.h"+/*+ * Flags used as delimiter: + * 0xffffffff => MSB 32-bit all 1s + * 0xef10 => emulated (virtual) function IO + * 0x0000 => 16-bits reserved for flags + */ +#define VFIO_MIG_FLAG_END_OF_STATE (0xffffffffef100001ULL) +#define VFIO_MIG_FLAG_DEV_CONFIG_STATE (0xffffffffef100002ULL) +#define VFIO_MIG_FLAG_DEV_SETUP_STATE (0xffffffffef100003ULL) +#define VFIO_MIG_FLAG_DEV_DATA_STATE (0xffffffffef100004ULL) + static inline int vfio_mig_access(VFIODevice *vbasedev, void *val, int count, off_t off, bool iswrite) { @@ -166,6 +180,65 @@ static int vfio_migration_set_state(VFIODevice *vbasedev, uint32_t mask, return 0; }+/* ---------------------------------------------------------------------- */+ +static int vfio_save_setup(QEMUFile *f, void *opaque) +{ + VFIODevice *vbasedev = opaque; + VFIOMigration *migration = vbasedev->migration; + int ret; + + trace_vfio_save_setup(vbasedev->name); + + qemu_put_be64(f, VFIO_MIG_FLAG_DEV_SETUP_STATE); + + if (migration->region.mmaps) { + qemu_mutex_lock_iothread(); + ret = vfio_region_mmap(&migration->region); + qemu_mutex_unlock_iothread();Please add a comment identifying why the iothread mutex lock is necessary here.+ if (ret) { + error_report("%s: Failed to mmap VFIO migration region %d: %s", + vbasedev->name, migration->region.nr,We don't support multiple migration regions, is it useful to include the region index here?
Ok. Removing region.nr
+ strerror(-ret)); + error_report("%s: Falling back to slow path", vbasedev->name); + } + } + + ret = vfio_migration_set_state(vbasedev, VFIO_DEVICE_STATE_MASK, + VFIO_DEVICE_STATE_SAVING); + if (ret) { + error_report("%s: Failed to set state SAVING", vbasedev->name); + return ret; + }Again, doesn't match the function semantics that success only means the device is in a non-error state, maybe the one that was asked for.
Fixed in patch 05.
+ + qemu_put_be64(f, VFIO_MIG_FLAG_END_OF_STATE);What's the overall purpose of writing these markers into the migration stream? vfio_load_state() doesn't do anything with this other than validate that the end-of-state immediately follows. Is this a placeholder for something in the future?
Its not placeholder, it is used in vfio_load_state() to determine upto what point to loop to fetch data for each state, otherwise how would we know when to stop reading data from stream for that VFIO device.
+ + ret = qemu_file_get_error(f); + if (ret) { + return ret; + } + + return 0; +} + +static void vfio_save_cleanup(void *opaque) +{ + VFIODevice *vbasedev = opaque; + VFIOMigration *migration = vbasedev->migration; + + if (migration->region.mmaps) { + vfio_region_unmap(&migration->region); + } + trace_vfio_save_cleanup(vbasedev->name); +} + +static SaveVMHandlers savevm_vfio_handlers = { + .save_setup = vfio_save_setup, + .save_cleanup = vfio_save_cleanup, +}; + +/* ---------------------------------------------------------------------- */ + static void vfio_vmstate_change(void *opaque, int running, RunState state) { VFIODevice *vbasedev = opaque; @@ -225,6 +298,8 @@ static int vfio_migration_init(VFIODevice *vbasedev, struct vfio_region_info *info) { int ret = -EINVAL; + char id[256] = ""; + Object *obj;if (!vbasedev->ops->vfio_get_object) {return ret; @@ -241,6 +316,22 @@ static int vfio_migration_init(VFIODevice *vbasedev, return ret; }+ obj = vbasedev->ops->vfio_get_object(vbasedev);+ + if (obj) { + DeviceState *dev = DEVICE(obj); + char *oid = vmstate_if_get_id(VMSTATE_IF(dev)); + + if (oid) { + pstrcpy(id, sizeof(id), oid); + pstrcat(id, sizeof(id), "/"); + g_free(oid); + } + }Here's where vfio_migration_init() starts using vfio_get_object() as I referenced back on patch 04. We might as well get the object before calling vfio_migration_region_init() and then pass the object. The conditional branch to handle obj is strange here too, it's fatal if vfio_migration_region_init() doesn't find an object, why do we handle it as optional here? Also, what is this doing? Comments would be nice... Thanks,
Changing it as I mentioned in other patch reply. Thanks.
Alex+ pstrcat(id, sizeof(id), "vfio"); + + register_savevm_live(id, VMSTATE_INSTANCE_ID_ANY, 1, &savevm_vfio_handlers, + vbasedev); vbasedev->vm_state = qemu_add_vm_change_state_handler(vfio_vmstate_change, vbasedev); vbasedev->migration_state.notify = vfio_migration_state_notifier; diff --git a/hw/vfio/trace-events b/hw/vfio/trace-events index bcb3fa7314d7..982d8dccb219 100644 --- a/hw/vfio/trace-events +++ b/hw/vfio/trace-events @@ -152,3 +152,5 @@ vfio_migration_probe(const char *name, uint32_t index) " (%s) Region %d" vfio_migration_set_state(const char *name, uint32_t state) " (%s) state %d" vfio_vmstate_change(const char *name, int running, const char *reason, uint32_t dev_state) " (%s) running %d reason %s device state %d" vfio_migration_state_notifier(const char *name, const char *state) " (%s) state %s" +vfio_save_setup(const char *name) " (%s)" +vfio_save_cleanup(const char *name) " (%s)"
[Prev in Thread] | Current Thread | [Next in Thread] |