The problem is specific to the case of BIST reset issued to IPR
adapter on the guest side. The IPR driver calls pci_save_state(),
issues BIST reset and then pci_restore_state(). The issued BIST
cleans out MSIx table and pci_restore_state() doesn't restore
the MSIx table as expected. Eventually, MSIx messages with all
zeros are sent and causes EEH error on Power platform.
The patch fixes it by writing MSIx message to MSIx table before
reenabling the individual interrupts in the following path:
qemu/hw/pci/msix.c::msix_table_mmio_write
msix_handle_mask_update
msix_fire_vector_notifier
qemu/hw/misc/vfio.c::vfio_msix_vector_use
vfio_msix_vector_do_use
IOCTL Command VFIO_DEVICE_SET_IRQS to VFIO-PCI
vfio/pci/vfio_pci.c::vfio_pci_ioctl
vfio/pci/vfio_pci_intrs.c::vfio_pci_set_irqs_ioctl
vfio_pci_set_msi_trigger
vfio_msi_set_block
vfio_msi_set_vector_signal
Reported-by: Wen Xiong <wenxiong@xxxxxxxxxx>
Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
---
drivers/vfio/pci/vfio_pci_intrs.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 2103576..83e0638 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -17,6 +17,7 @@
#include <linux/interrupt.h>
#include <linux/eventfd.h>
#include <linux/pci.h>
+#include <linux/msi.h>
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/vfio.h>
@@ -517,6 +518,7 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
struct pci_dev *pdev = vdev->pdev;
int irq = msix ? vdev->msix[vector].vector : pdev->irq + vector;
char *name = msix ? "vfio-msix" : "vfio-msi";
+ struct msi_msg msg;
struct eventfd_ctx *trigger;
int ret;
@@ -544,6 +546,15 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
return PTR_ERR(trigger);
}
+ /* We possiblly lose the MSI/MSIx message in some cases, one
+ * of which is pci_save_state(), BIST reset and pci_restore_state()
+ * for IPR adapter. The BIST reset cleans out MSIx table and we
+ * don't have chance to restore it. Here, we have the trick to
+ * restore it before enabling individual interrupts. For MSI messages,
+ * it's harmless to write them back.
+ */
+ get_cached_msi_msg(irq, &msg);
+ write_msi_msg(irq, &msg);
ret = request_irq(irq, vfio_msihandler, 0,
vdev->ctx[vector].name, trigger);
if (ret) {
--
1.7.10.4
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