The problem is specific to the case of BIST issued applied to IPR
adapter on the guest side. After BIST reset, we lose everything
in MSIx table and we never have chance update MSIx messages for
those enabled interrupts to MSIx table.
The patch fixes it by writing MSIx message to MSIx table before
reenabling them.
Reported-by: Wen Xiong <wenxiong@xxxxxxxxxx>
Signed-off-by: Gavin Shan <shangw@xxxxxxxxxxxxxxxxxx>
---
drivers/vfio/pci/vfio_pci_intrs.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 2103576..279ebd0 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 +546,23 @@ 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.
+ * For example, BIST reset on IPR adapter. The MSIx table
+ * is cleaned out. However, we never get chance to put
+ * MSIx messages to MSIx table because all MSIx stuff is
+ * being cached in QEMU. Here, we had the trick to put the
+ * MSI/MSIx message back.
+ *
+ * Basically, we needn't worry about MSI messages. However,
+ * it's not harmful and there might be cases of PCI config data
+ * lost because of cached PCI config data in QEMU again.
+ *
+ * Note that we should flash the message prior to enabling
+ * the corresponding interrupt by request_irq().
+ */
+ 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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