| Message ID | 1399944924-1200-5-git-send-email-gwshan@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 13, 2014 at 11:35:24AM +1000, Gavin Shan wrote: >The MSIx vector table lives in device memory, which may be cleared as >part of a backdoor device reset. This is the case on the IBM IPR HBA >when the BIST is run on the device. When assigned to a QEMU guest, >the guest driver does a pci_save_state(), issues a BIST, then does a >pci_restore_state(). The BIST clears the MSIx vector table, but due >to the way interrupts are configured the pci_restore_state() does not >restore the vector table as expected. Eventually this results in an >EEH error on Power platforms when the device attempts to signal an >interrupt with the zero'd table entry. > >Fix the problem by restoring the host cached MSI message prior to >enabling each vector. > >Reported-by: Wen Xiong <wenxiong@linux.vnet.ibm.com> >Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com> >Signed-off-by: Alex Williamson <alex.williamson@redhat.com> >--- Sorry about that the following line was missed. I'll add that and send "v3" out. #include <linux/msi.h> > drivers/vfio/pci/vfio_pci_intrs.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > >diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c >index 9dd49c9..409346f 100644 >--- a/drivers/vfio/pci/vfio_pci_intrs.c >+++ b/drivers/vfio/pci/vfio_pci_intrs.c >@@ -548,6 +548,20 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev, > return PTR_ERR(trigger); > } > >+ /* >+ * The MSIx vector table resides in device memory which may be cleared >+ * via backdoor resets. We don't allow direct access to the vector >+ * table so even if a userspace driver attempts to save/restore around >+ * such a reset it would be unsuccessful. To avoid this, restore the >+ * cached value of the message prior to enabling. >+ */ >+ if (msix) { >+ struct msi_msg msg; >+ >+ 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) { Thanks, Gavin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 9dd49c9..409346f 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -548,6 +548,20 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev, return PTR_ERR(trigger); } + /* + * The MSIx vector table resides in device memory which may be cleared + * via backdoor resets. We don't allow direct access to the vector + * table so even if a userspace driver attempts to save/restore around + * such a reset it would be unsuccessful. To avoid this, restore the + * cached value of the message prior to enabling. + */ + if (msix) { + struct msi_msg msg; + + 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) {