If MSI doesn't support per-vector masking capability and
PCI_MSI_FLAGS_MASKBIT isn't set in message control field, the function
vfio_pci_msi_vector_write() will directly bail out for this case and
every vector's 'virt_state' keeps setting bit VFIO_PCI_MSI_STATE_MASKED.
This results in the state maintained in 'virt_state' cannot really
reflect the MSI hardware state; finally it will mislead the function
vfio_pci_update_msi_entry() to skip IRQ forwarding with below flow:
vfio_pci_update_msi_entry() {
[...]
if (msi_is_masked(entry->virt_state) == msi_is_masked(entry->phys_state))
return 0; ==> skip IRQ forwarding
[...]
}
To fix this issue, when detect PCI_MSI_FLAGS_MASKBIT is not set in the
message control field, this patch simply clears bit
VFIO_PCI_MSI_STATE_MASKED for all vectors 'virt_state'; at the end
vfio_pci_update_msi_entry() can forward MSI IRQ successfully.
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
vfio/pci.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/vfio/pci.c b/vfio/pci.c
index ba971eb..4fd24ac 100644
--- a/vfio/pci.c
+++ b/vfio/pci.c
@@ -363,8 +363,18 @@ static int vfio_pci_msi_vector_write(struct kvm *kvm, struct vfio_device *vdev,
struct vfio_pci_device *pdev = &vdev->pci;
struct msi_cap_64 *msi_cap_64 = PCI_CAP(&pdev->hdr, pdev->msi.pos);
- if (!(msi_cap_64->ctrl & PCI_MSI_FLAGS_MASKBIT))
+ if (!(msi_cap_64->ctrl & PCI_MSI_FLAGS_MASKBIT)) {
+ /*
+ * If MSI doesn't support per-vector masking capability,
+ * simply unmask for all vectors.
+ */
+ for (i = 0; i < pdev->msi.nr_entries; i++) {
+ entry = &pdev->msi.entries[i];
+ msi_set_masked(entry->virt_state, false);
+ }
+
return 0;
+ }
if (msi_cap_64->ctrl & PCI_MSI_FLAGS_64BIT)
mask_pos = PCI_MSI_MASK_64;
--
2.19.1
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