Dynamic MSI-X is supported. Clear VFIO_IRQ_INFO_NORESIZE
to provide guidance to user space.
Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
---
Changes since V2:
- Use new vdev->has_dyn_msix property instead of calling
pci_msix_can_alloc_dyn() directly. (Alex)
Changes since RFC V1:
- Only advertise VFIO_IRQ_INFO_NORESIZE for MSI-X devices that
can actually support dynamic allocation. (Alex)
drivers/vfio/pci/vfio_pci_core.c | 4 +++-
include/uapi/linux/vfio.h | 3 +++
2 files changed, 6 insertions(+), 1 deletion(-)
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index a3635a8e54c8..4050ad3388c2 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -1114,7 +1114,9 @@ static int vfio_pci_ioctl_get_irq_info(struct vfio_pci_core_device *vdev,
if (info.index == VFIO_PCI_INTX_IRQ_INDEX)
info.flags |=
(VFIO_IRQ_INFO_MASKABLE | VFIO_IRQ_INFO_AUTOMASKED);
- else
+ else if ((info.index != VFIO_PCI_MSIX_IRQ_INDEX) ||
+ (info.index == VFIO_PCI_MSIX_IRQ_INDEX &&
+ !vdev->has_dyn_msix))
info.flags |= VFIO_IRQ_INFO_NORESIZE;
return copy_to_user(arg, &info, minsz) ? -EFAULT : 0;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 0552e8dcf0cb..1a36134cae5c 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -511,6 +511,9 @@ struct vfio_region_info_cap_nvlink2_lnkspd {
* then add and unmask vectors, it's up to userspace to make the decision
* whether to allocate the maximum supported number of vectors or tear
* down setup and incrementally increase the vectors as each is enabled.
+ * Absence of the NORESIZE flag indicates that vectors can be enabled
+ * and disabled dynamically without impacting other vectors within the
+ * index.
*/
struct vfio_irq_info {
__u32 argsz;
--
2.34.1
