[PATCH mlx5-next 2/7] vfio: Add an API to check migration state transition validity
From: Leon Romanovsky <leon@kernel.org>
Date: 2021-09-22 10:39:09
Also in:
kvm, linux-pci, linux-rdma, lkml
Subsystem:
the rest, vfio driver · Maintainers:
Linus Torvalds, Alex Williamson
From: Yishai Hadas <yishaih@nvidia.com> Add an API in the core layer to check migration state transition validity as part of a migration flow. The valid transitions follow the expected usage as described in uapi/vfio.h and triggered by QEMU. This ensures that all migration implementations follow a consistent migration state machine. Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com> Signed-off-by: Leon Romanovsky <leonro@nvidia.com> --- drivers/vfio/vfio.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/linux/vfio.h | 1 + 2 files changed, 42 insertions(+)
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3c034fe14ccb..c3ca33e513c8 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c@@ -1664,6 +1664,47 @@ static int vfio_device_fops_release(struct inode *inode, struct file *filep) return 0; } +/** + * vfio_change_migration_state_allowed - Checks whether a migration state + * transition is valid. + * @new_state: The new state to move to. + * @old_state: The old state. + * Return: true if the transition is valid. + */ +bool vfio_change_migration_state_allowed(u32 new_state, u32 old_state) +{ + enum { MAX_STATE = VFIO_DEVICE_STATE_RESUMING }; + static const u8 vfio_from_state_table[MAX_STATE + 1][MAX_STATE + 1] = { + [VFIO_DEVICE_STATE_STOP] = { + [VFIO_DEVICE_STATE_RUNNING] = 1, + [VFIO_DEVICE_STATE_RESUMING] = 1, + }, + [VFIO_DEVICE_STATE_RUNNING] = { + [VFIO_DEVICE_STATE_STOP] = 1, + [VFIO_DEVICE_STATE_SAVING] = 1, + [VFIO_DEVICE_STATE_SAVING | VFIO_DEVICE_STATE_RUNNING] = 1, + }, + [VFIO_DEVICE_STATE_SAVING] = { + [VFIO_DEVICE_STATE_STOP] = 1, + [VFIO_DEVICE_STATE_RUNNING] = 1, + }, + [VFIO_DEVICE_STATE_SAVING | VFIO_DEVICE_STATE_RUNNING] = { + [VFIO_DEVICE_STATE_RUNNING] = 1, + [VFIO_DEVICE_STATE_SAVING] = 1, + }, + [VFIO_DEVICE_STATE_RESUMING] = { + [VFIO_DEVICE_STATE_RUNNING] = 1, + [VFIO_DEVICE_STATE_STOP] = 1, + }, + }; + + if (new_state > MAX_STATE || old_state > MAX_STATE) + return false; + + return vfio_from_state_table[old_state][new_state]; +} +EXPORT_SYMBOL_GPL(vfio_change_migration_state_allowed); + static long vfio_device_fops_unl_ioctl(struct file *filep, unsigned int cmd, unsigned long arg) {
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b53a9557884a..e65137a708f1 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h@@ -83,6 +83,7 @@ extern struct vfio_device *vfio_device_get_from_dev(struct device *dev); extern void vfio_device_put(struct vfio_device *device); int vfio_assign_device_set(struct vfio_device *device, void *set_id); +bool vfio_change_migration_state_allowed(u32 new_state, u32 old_state); /* events for the backend driver notify callback */ enum vfio_iommu_notify_type {
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2.31.1