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-rw-r--r--Documentation/vfio.txt87
1 files changed, 84 insertions, 3 deletions
diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
index b9ca02370d46..96978eced341 100644
--- a/Documentation/vfio.txt
+++ b/Documentation/vfio.txt
@@ -305,7 +305,15 @@ faster, the map/unmap handling has been implemented in real mode which provides
an excellent performance which has limitations such as inability to do
locked pages accounting in real time.
-So 3 additional ioctls have been added:
+4) According to sPAPR specification, A Partitionable Endpoint (PE) is an I/O
+subtree that can be treated as a unit for the purposes of partitioning and
+error recovery. A PE may be a single or multi-function IOA (IO Adapter), a
+function of a multi-function IOA, or multiple IOAs (possibly including switch
+and bridge structures above the multiple IOAs). PPC64 guests detect PCI errors
+and recover from them via EEH RTAS services, which works on the basis of
+additional ioctl commands.
+
+So 4 additional ioctls have been added:
VFIO_IOMMU_SPAPR_TCE_GET_INFO - returns the size and the start
of the DMA window on the PCI bus.
@@ -316,9 +324,12 @@ So 3 additional ioctls have been added:
VFIO_IOMMU_DISABLE - disables the container.
+ VFIO_EEH_PE_OP - provides an API for EEH setup, error detection and recovery.
The code flow from the example above should be slightly changed:
+ struct vfio_eeh_pe_op pe_op = { .argsz = sizeof(pe_op), .flags = 0 };
+
.....
/* Add the group to the container */
ioctl(group, VFIO_GROUP_SET_CONTAINER, &container);
@@ -342,9 +353,79 @@ The code flow from the example above should be slightly changed:
dma_map.flags = VFIO_DMA_MAP_FLAG_READ | VFIO_DMA_MAP_FLAG_WRITE;
/* Check here is .iova/.size are within DMA window from spapr_iommu_info */
-
ioctl(container, VFIO_IOMMU_MAP_DMA, &dma_map);
- .....
+
+ /* Get a file descriptor for the device */
+ device = ioctl(group, VFIO_GROUP_GET_DEVICE_FD, "0000:06:0d.0");
+
+ ....
+
+ /* Gratuitous device reset and go... */
+ ioctl(device, VFIO_DEVICE_RESET);
+
+ /* Make sure EEH is supported */
+ ioctl(container, VFIO_CHECK_EXTENSION, VFIO_EEH);
+
+ /* Enable the EEH functionality on the device */
+ pe_op.op = VFIO_EEH_PE_ENABLE;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /* You're suggested to create additional data struct to represent
+ * PE, and put child devices belonging to same IOMMU group to the
+ * PE instance for later reference.
+ */
+
+ /* Check the PE's state and make sure it's in functional state */
+ pe_op.op = VFIO_EEH_PE_GET_STATE;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /* Save device state using pci_save_state().
+ * EEH should be enabled on the specified device.
+ */
+
+ ....
+
+ /* When 0xFF's returned from reading PCI config space or IO BARs
+ * of the PCI device. Check the PE's state to see if that has been
+ * frozen.
+ */
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /* Waiting for pending PCI transactions to be completed and don't
+ * produce any more PCI traffic from/to the affected PE until
+ * recovery is finished.
+ */
+
+ /* Enable IO for the affected PE and collect logs. Usually, the
+ * standard part of PCI config space, AER registers are dumped
+ * as logs for further analysis.
+ */
+ pe_op.op = VFIO_EEH_PE_UNFREEZE_IO;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /*
+ * Issue PE reset: hot or fundamental reset. Usually, hot reset
+ * is enough. However, the firmware of some PCI adapters would
+ * require fundamental reset.
+ */
+ pe_op.op = VFIO_EEH_PE_RESET_HOT;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+ pe_op.op = VFIO_EEH_PE_RESET_DEACTIVATE;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /* Configure the PCI bridges for the affected PE */
+ pe_op.op = VFIO_EEH_PE_CONFIGURE;
+ ioctl(container, VFIO_EEH_PE_OP, &pe_op);
+
+ /* Restored state we saved at initialization time. pci_restore_state()
+ * is good enough as an example.
+ */
+
+ /* Hopefully, error is recovered successfully. Now, you can resume to
+ * start PCI traffic to/from the affected PE.
+ */
+
+ ....
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