[RFC PATCH v3 13/20] vfio/pci: Track PCI recovery state

[Shameer Kolothum <skolothumtho@nvidia.com>]

PCI error recovery spans several callbacks. Add state to track its
progress so later patches can keep access blocked until recovery
succeeds and leave it blocked if recovery fails.

Add recovery flags, a sequence counter and saved PCI_COMMAND state.
Initialize per-open state during open and clear it on close. Keep host
recovery state separate so close does not lose an ongoing recovery that
must prevent reopening.

Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
---
 include/linux/vfio_pci_core.h    | 18 +++++++++++++++++-
 drivers/vfio/pci/vfio_pci_core.c |  7 +++++++
 2 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 88aa7b752231..f2b64420cb07 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -98,6 +98,11 @@ static inline int vfio_pci_core_get_dmabuf_phys(
 }
 #endif
 
+#define VFIO_PCI_RECOVERY_IN_PROGRESS	BIT(0)
+#define VFIO_PCI_RECOVERY_FROZEN	BIT(1)
+#define VFIO_PCI_RECOVERY_RESET		BIT(2)
+#define VFIO_PCI_RECOVERY_FAILED	BIT(3)
+
 struct vfio_pci_access_ops;
 
 struct vfio_pci_core_device {
@@ -159,7 +164,18 @@ struct vfio_pci_core_device {
 	const struct vfio_pci_access_ops __rcu *access_ops;
 	/* Set after open completes, cleared before close tears down state. */
 	bool			device_open;
-	struct mutex		access_lock;	/* protects changes to access ops and flags */
+	struct mutex		access_lock;	/* protects access and recovery state */
+	u32			pci_recovery_flags;
+	u64			pci_recovery_sequence;
+	/* Saved PCI_COMMAND, valid when pci_recovery_command_valid is set. */
+	u16			pci_recovery_command;
+	bool			pci_recovery_enabled;
+	bool			pci_recovery_command_valid;
+	/*
+	 * Host recovery is still running. Protected by access_lock and kept across
+	 * close, unlike recovery status for the current open.
+	 */
+	bool			pci_recovery_host_active;
 	struct list_head	dmabufs;
 };
 
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 0299f5afca91..cdc6bafe9861 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -923,8 +923,11 @@ void vfio_pci_core_close_device(struct vfio_device *core_vdev)
 
 	if (vdev->pci_recovery_supported) {
 		scoped_guard(mutex, &vdev->access_lock) {
+			WRITE_ONCE(vdev->pci_recovery_enabled, false);
+			vdev->pci_recovery_command_valid = false;
 			WRITE_ONCE(vdev->device_open, false);
 			vfio_pci_core_block_access(vdev);
+			WRITE_ONCE(vdev->pci_recovery_flags, 0);
 		}
 	}
 
@@ -963,6 +966,10 @@ void vfio_pci_core_finish_enable(struct vfio_pci_core_device *vdev)
 
 	if (vdev->pci_recovery_supported) {
 		guard(mutex)(&vdev->access_lock);
+		WRITE_ONCE(vdev->pci_recovery_flags, 0);
+		vdev->pci_recovery_sequence = 0;
+		vdev->pci_recovery_command_valid = false;
+		WRITE_ONCE(vdev->pci_recovery_enabled, false);
 		WRITE_ONCE(vdev->device_open, true);
 		rcu_assign_pointer(vdev->access_ops, &vfio_pci_live_ops);
 	}
-- 
2.43.0