vfio: rework vfio_irq_set payload setting
struct vfio_irq_set from the kernel headers contains a variable sized
array to hold a payload. The vfio_irq_eventfd struct puts the "fd"
member right after this, hoping it to automatically fit in the payload slot.
But having a variable sized type not at the end of a struct is a GNU C
extension, so clang will refuse to compile this.
Solve this by somewhat doing the compiler's job and place the payload
manually at the end of the structure.
Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/vfio/pci.c b/vfio/pci.c
index a408632..76e24c1 100644
--- a/vfio/pci.c
+++ b/vfio/pci.c
@@ -9,11 +9,16 @@
#include <sys/time.h>
/* Wrapper around UAPI vfio_irq_set */
-struct vfio_irq_eventfd {
+union vfio_irq_eventfd {
struct vfio_irq_set irq;
- int fd;
+ u8 buffer[sizeof(struct vfio_irq_set) + sizeof(int)];
};
+static void set_vfio_irq_eventd_payload(union vfio_irq_eventfd *evfd, int fd)
+{
+ memcpy(&evfd->irq.data, &fd, sizeof(fd));
+}
+
#define msi_is_enabled(state) ((state) & VFIO_PCI_MSI_STATE_ENABLED)
#define msi_is_masked(state) ((state) & VFIO_PCI_MSI_STATE_MASKED)
#define msi_is_empty(state) ((state) & VFIO_PCI_MSI_STATE_EMPTY)
@@ -38,7 +43,7 @@
int *eventfds;
struct vfio_pci_device *pdev = &vdev->pci;
struct vfio_pci_msi_common *msis = msix ? &pdev->msix : &pdev->msi;
- struct vfio_irq_eventfd single = {
+ union vfio_irq_eventfd single = {
.irq = {
.argsz = sizeof(single),
.flags = VFIO_IRQ_SET_DATA_EVENTFD |
@@ -117,7 +122,7 @@
continue;
single.irq.start = i;
- single.fd = fd;
+ set_vfio_irq_eventd_payload(&single, fd);
ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &single);
if (ret < 0) {
@@ -1021,8 +1026,8 @@
{
int ret;
int trigger_fd, unmask_fd;
- struct vfio_irq_eventfd trigger;
- struct vfio_irq_eventfd unmask;
+ union vfio_irq_eventfd trigger;
+ union vfio_irq_eventfd unmask;
struct vfio_pci_device *pdev = &vdev->pci;
int gsi = pdev->intx_gsi;
@@ -1058,7 +1063,7 @@
.start = 0,
.count = 1,
};
- trigger.fd = trigger_fd;
+ set_vfio_irq_eventd_payload(&trigger, trigger_fd);
ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &trigger);
if (ret < 0) {
@@ -1073,7 +1078,7 @@
.start = 0,
.count = 1,
};
- unmask.fd = unmask_fd;
+ set_vfio_irq_eventd_payload(&unmask, unmask_fd);
ret = ioctl(vdev->fd, VFIO_DEVICE_SET_IRQS, &unmask);
if (ret < 0) {
