[PATCH v2] vfio/pci: Support error recovery

[Cao jin]

Support serious device error recovery

Signed-off-by: Cao jin <caoj.fnst@xxxxxxxxxxxxxx>
---
 drivers/vfio/pci/vfio_pci.c         | 70 +++++++++++++++++++++++++++++++++++--
 drivers/vfio/pci/vfio_pci_private.h |  2 ++
 2 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 712a849..752af20 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data,
 {
 	struct vfio_pci_device *vdev = device_data;
 	unsigned long minsz;
+	int ret;
+
+	if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
+	    cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
+		ret = wait_for_completion_interruptible(
+			&vdev->aer_completion);
+		if (ret)
+			return ret;
+	}
 
 	if (cmd == VFIO_DEVICE_GET_INFO) {
 		struct vfio_device_info info;
@@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf,
 {
 	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
 	struct vfio_pci_device *vdev = device_data;
+	int ret;
+
+	/* block all kinds of access during host recovery */
+	if (vdev->aer_recovering) {
+		ret = wait_for_completion_interruptible(
+			&vdev->aer_completion);
+		if (ret)
+			return ret;
+	}
 
 	if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions)
 		return -EINVAL;
@@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	vdev->irq_type = VFIO_PCI_NUM_IRQS;
 	mutex_init(&vdev->igate);
 	spin_lock_init(&vdev->irqlock);
+	init_completion(&vdev->aer_completion);
 
 	ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
 	if (ret) {
@@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
 {
 	struct vfio_pci_device *vdev;
 	struct vfio_device *device;
+	u32 uncor_status;
+	unsigned int aer_cap_offset;
+	int ret;
 
 	device = vfio_device_get_from_dev(&pdev->dev);
 	if (device == NULL)
@@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
 
+	/*
+	 * get device's uncorrectable error status as soon as possible,
+	 * and signal it to user space. The later we read it, the possibility
+	 * the register value is mangled grows.
+	 */
+	aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR);
+	ret = pci_read_config_dword(vdev->pdev, aer_cap_offset +
+                                    PCI_ERR_UNCOR_STATUS, &uncor_status);
+        if (ret)
+                return PCI_ERS_RESULT_DISCONNECT;
+
+	pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed
 	mutex_lock(&vdev->igate);
 
-	if (vdev->err_trigger)
-		eventfd_signal(vdev->err_trigger, 1);
+	vdev->aer_recovering = true;
+	reinit_completion(&vdev->aer_completion);
+
+	if (vdev->err_trigger && uncor_status) {
+		pr_info("device %d signal uncor status 0x%x to user",
+			pdev->devfn, uncor_status);
+		/* signal uncorrectable error status to user space */
+		eventfd_signal(vdev->err_trigger, uncor_status);
+        }
 
 	mutex_unlock(&vdev->igate);
 
@@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev,
 	return PCI_ERS_RESULT_CAN_RECOVER;
 }
 
+static void vfio_pci_aer_resume(struct pci_dev *pdev)
+{
+	struct vfio_pci_device *vdev;
+	struct vfio_device *device;
+
+	device = vfio_device_get_from_dev(&pdev->dev);
+	if (device == NULL)
+		return;
+
+	vdev = vfio_device_data(device);
+	if (vdev == NULL) {
+		vfio_device_put(device);
+		return;
+	}
+
+	mutex_lock(&vdev->igate);
+	vdev->aer_recovering = false;
+	mutex_unlock(&vdev->igate);
+
+	complete_all(&vdev->aer_completion);
+
+	vfio_device_put(device);
+}
+
 static const struct pci_error_handlers vfio_err_handlers = {
 	.error_detected = vfio_pci_aer_err_detected,
+	.resume         = vfio_pci_aer_resume,
 };
 
 static struct pci_driver vfio_pci_driver = {
diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h
index 8a7d546..ba8471f 100644
--- a/drivers/vfio/pci/vfio_pci_private.h
+++ b/drivers/vfio/pci/vfio_pci_private.h
@@ -83,6 +83,8 @@ struct vfio_pci_device {
 	bool			bardirty;
 	bool			has_vga;
 	bool			needs_reset;
+	bool			aer_recovering;
+	struct completion	aer_completion;
 	struct pci_saved_state	*pci_saved_state;
 	int			refcnt;
 	struct eventfd_ctx	*err_trigger;
-- 
1.8.3.1