On 2/3/26 08:30, Vivek Kasireddy wrote:
In addition to memfd, a blob resource can also have its backing
storage in a VFIO device region. Since, there is no effective way
to determine where the backing storage is located, we first try to
create a dmabuf assuming it is in memfd. If that fails, we try to
create a dmabuf assuming it is in VFIO device region.
So, we first call virtio_gpu_create_udmabuf() to check if the blob's
backing storage is located in a memfd or not. If it is not, we invoke
the vfio_device_create_dmabuf() API which identifies the right VFIO
device and eventually creates a dmabuf fd.
Note that in virtio_gpu_remap_dmabuf(), we first try to test if
the VFIO dmabuf exporter supports mmap or not. If it doesn't, we
fall back to the vfio_device_mmap_dmabuf() API to get a mapping
created for the dmabuf.
Cc: Marc-André Lureau <[email protected]>
Cc: Alex Bennée <[email protected]>
Cc: Akihiko Odaki <[email protected]>
Cc: Dmitry Osipenko <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Cédric Le Goater <[email protected]>
Signed-off-by: Vivek Kasireddy <[email protected]>
---
hw/display/Kconfig | 5 ++++
hw/display/virtio-gpu-dmabuf.c | 49 ++++++++++++++++++++++++++--------
2 files changed, 43 insertions(+), 11 deletions(-)
diff --git a/hw/display/Kconfig b/hw/display/Kconfig
index 1e95ab28ef..0d090f25f5 100644
--- a/hw/display/Kconfig
+++ b/hw/display/Kconfig
@@ -106,6 +106,11 @@ config VIRTIO_VGA
depends on VIRTIO_PCI
select VGA
+config VIRTIO_GPU_VFIO_BLOB
+ bool
+ default y
+ depends on VFIO
+
config VHOST_USER_GPU
bool
default y
diff --git a/hw/display/virtio-gpu-dmabuf.c b/hw/display/virtio-gpu-dmabuf.c
index 22e66fbb12..2e65f21dda 100644
--- a/hw/display/virtio-gpu-dmabuf.c
+++ b/hw/display/virtio-gpu-dmabuf.c
@@ -18,6 +18,7 @@
#include "ui/console.h"
#include "hw/virtio/virtio-gpu.h"
#include "hw/virtio/virtio-gpu-pixman.h"
+#include "hw/vfio/vfio-device.h"
#include "trace.h"
#include "system/ramblock.h"
#include "system/hostmem.h"
@@ -27,6 +28,23 @@
#include "standard-headers/linux/udmabuf.h"
#include "standard-headers/drm/drm_fourcc.h"
+static bool virtio_gpu_create_vfio_dmabuf(struct virtio_gpu_simple_resource *r,
+ Error **errp)
+{
+ bool ret = false;
+#if defined(VIRTIO_GPU_VFIO_BLOB)
+ int fd;
+
+ if (!vfio_device_create_dmabuf(r->iov, r->iov_cnt, &fd, errp)) {
+ return false;
+ }
+
+ ret = true;
+ r->dmabuf_fd = fd;
+#endif
+ return ret;
+}
+
static bool virtio_gpu_create_udmabuf(struct virtio_gpu_simple_resource *res,
Error **errp)
{
@@ -72,18 +90,25 @@ static bool virtio_gpu_create_udmabuf(struct
virtio_gpu_simple_resource *res,
}
static bool virtio_gpu_remap_dmabuf(struct virtio_gpu_simple_resource *res,
- Error **err1)
+ Error **err1, Error **err2)
This looks wrong. Why do we need 2 errors ?
C.
{
+ bool ret = true;
void *map;
map = mmap(NULL, res->blob_size, PROT_READ, MAP_SHARED, res->dmabuf_fd, 0);
if (map == MAP_FAILED) {
error_setg_errno(err1, errno, "dmabuf mmap failed");
- res->remapped = NULL;
- return false;
+ map = NULL;
+ ret = false;
+#if defined(VIRTIO_GPU_VFIO_BLOB)
+ if (vfio_device_mmap_dmabuf(res->iov, res->iov_cnt, &map,
+ res->blob_size, err2)) {
+ ret = true;
+ }
+#endif
}
res->remapped = map;
- return true;
+ return ret;
}
static void virtio_gpu_destroy_dmabuf(struct virtio_gpu_simple_resource *res)
@@ -137,7 +162,7 @@ bool virtio_gpu_have_udmabuf(void)
void virtio_gpu_init_dmabuf(struct virtio_gpu_simple_resource *res)
{
- Error *err1 = NULL;
+ Error *err1 = NULL, *err2 = NULL;
void *pdata = NULL;
res->dmabuf_fd = -1;
@@ -146,12 +171,16 @@ void virtio_gpu_init_dmabuf(struct
virtio_gpu_simple_resource *res)
pdata = res->iov[0].iov_base;
} else {
if (!virtio_gpu_create_udmabuf(res, &err1)) {
- error_report_err(err1);
- return;
+ if (!virtio_gpu_create_vfio_dmabuf(res, &err2)) {
+ error_report_err(err1);
+ error_report_err(err2);
+ return;
+ }
}
- if (!virtio_gpu_remap_dmabuf(res, &err1)) {
+ if (!virtio_gpu_remap_dmabuf(res, &err1, &err2)) {
error_report_err(err1);
+ error_report_err(err2);
return;
}
pdata = res->remapped;
@@ -162,9 +191,7 @@ void virtio_gpu_init_dmabuf(struct
virtio_gpu_simple_resource *res)
void virtio_gpu_fini_dmabuf(struct virtio_gpu_simple_resource *res)
{
- if (res->remapped) {
- virtio_gpu_destroy_dmabuf(res);
- }
+ virtio_gpu_destroy_dmabuf(res);
}
static void virtio_gpu_free_dmabuf(VirtIOGPU *g, VGPUDMABuf *dmabuf)
