migration: various dirty page tracking fixes (#457)

- document how to use a vfio-user device with libvirt
- document how to use SPDK's nvmf/vfio-user target with libvirt
- replace vfio_bitmap with vfio_user_bitmap and vfio_iommu_type1_dirty_bitmap_get with vfio_user_bitmap_range
- fix bug for calculating number of pages needed for dirty page bitmap
- align number of bytes for dirty page bitmap to QWORD
- add debug messages around dirty page tracking
- only support flags=0 when doing DMA unmap
- set device state to running after reset
- allow region read/write even if device is in stopped state
- allow transitioning from stopped/stop-and-copy state to running state
- fix unit tests

Signed-off-by: Thanos Makatos <thanos.makatos@nutanix.com>
Reviewed-by: John Levon <john.levon@nutanix.com>

1 files changed, 19 insertions, 1 deletions

diff --git a/lib/migration_priv.h b/lib/migration_priv.h
index bf47621..1a0496f 100644
--- a/lib/migration_priv.h
+++ b/lib/migration_priv.h
@@ -75,7 +75,9 @@ struct migr_state_data {
 /* valid migration state transitions */
 static const struct migr_state_data migr_states[(VFIO_DEVICE_STATE_MASK + 1)] = {
     [VFIO_DEVICE_STATE_STOP] = {
-        .state = 1 << VFIO_DEVICE_STATE_STOP,
+        .state =
+            (1 << VFIO_DEVICE_STATE_STOP) |
+            (1 << VFIO_DEVICE_STATE_RUNNING),
         .name = "stopped"
     },
     [VFIO_DEVICE_STATE_RUNNING] = {
@@ -91,6 +93,7 @@ static const struct migr_state_data migr_states[(VFIO_DEVICE_STATE_MASK + 1)] =
     [VFIO_DEVICE_STATE_SAVING] = {
         .state =
             (1 << VFIO_DEVICE_STATE_STOP) |
+            (1 << VFIO_DEVICE_STATE_RUNNING) |
             (1 << VFIO_DEVICE_STATE_SAVING) |
             (1 << VFIO_DEVICE_STATE_ERROR),
         .name = "stop-and-copy"
@@ -112,6 +115,21 @@ static const struct migr_state_data migr_states[(VFIO_DEVICE_STATE_MASK + 1)] =
     }
 };
 
+MOCK_DECLARE(ssize_t, migration_region_access_registers, vfu_ctx_t *vfu_ctx,
+             char *buf, size_t count, loff_t pos,  bool is_write);
+
+MOCK_DECLARE(void, migr_state_transition, struct migration *migr,
+             enum migr_iter_state state);
+
+MOCK_DECLARE(vfu_migr_state_t, migr_state_vfio_to_vfu, uint32_t device_state);
+
+MOCK_DECLARE(int, state_trans_notify, vfu_ctx_t *vfu_ctx,
+             int (*fn)(vfu_ctx_t *, vfu_migr_state_t),
+             uint32_t vfio_device_state);
+
+MOCK_DECLARE(ssize_t, migr_trans_to_valid_state, vfu_ctx_t *vfu_ctx,
+             struct migration *migr, uint32_t device_state, bool notify);
+
 #endif
 
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