Subject: Re: [PATCH v7 06/10] virtio-gpu-dmabuf: Improve error
handling with 'Error **' and err enum
On 2026/02/23 17:00, Vivek Kasireddy wrote:
Make the error handling more robust in virtio_gpu_init_udmabuf()
by introducing 'Error **' parameter to capture errors and an enum
to categorize Guest and Host errors. This allows for better error
reporting and handling of errors from virtio_gpu_create_udmabuf()
and virtio_gpu_remap_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/virtio-gpu-dmabuf.c | 65 +++++++++++++++++++++++++---
------
1 file changed, 48 insertions(+), 17 deletions(-)
diff --git a/hw/display/virtio-gpu-dmabuf.c b/hw/display/virtio-gpu-
dmabuf.c
index 8d67ef7c2a..fdcf8e53a2 100644
--- a/hw/display/virtio-gpu-dmabuf.c
+++ b/hw/display/virtio-gpu-dmabuf.c
@@ -27,7 +27,17 @@
#include "standard-headers/linux/udmabuf.h"
#include "standard-headers/drm/drm_fourcc.h"
-static void virtio_gpu_create_udmabuf(struct
virtio_gpu_simple_resource *res)
+typedef enum VirtIOGPUErrorType {
+ VIRTIO_GPU_NO_ERROR = 0,
+ /* Guest is responsible for this error */
+ VIRTIO_GPU_GUEST_ERROR = 1,
+ /* Host is at fault for this error */
+ VIRTIO_GPU_HOST_ERROR = 2,
include/qapi/error.h says:
> - Whenever practical, also return a value that indicates success /
> failure. This can make the error checking more concise, and can
> avoid useless error object creation and destruction. Note that
> we still have many functions returning void. We recommend
> . bool-valued functions return true on success / false on failure,
> . pointer-valued functions return non-null / null pointer, and
> . integer-valued functions return non-negative / negative.
Do what it says. Non-negative if *errp is set. Negative otherwise.
+} VirtIOGPUErrorType;
+
+static VirtIOGPUErrorType
+virtio_gpu_create_udmabuf(struct virtio_gpu_simple_resource *res,
int *fd,
+ Error **errp)
{
g_autofree struct udmabuf_create_list *list = NULL;
RAMBlock *rb;
@@ -36,7 +46,8 @@ static void virtio_gpu_create_udmabuf(struct
virtio_gpu_simple_resource *res)
udmabuf = udmabuf_fd();
if (udmabuf < 0) {
- return;
+ error_setg(errp, "udmabuf device not available");
+ return VIRTIO_GPU_HOST_ERROR;
}
list = g_malloc0(sizeof(struct udmabuf_create_list) +
@@ -45,7 +56,8 @@ static void virtio_gpu_create_udmabuf(struct
virtio_gpu_simple_resource *res)
for (i = 0; i < res->iov_cnt; i++) {
rb = qemu_ram_block_from_host(res->iov[i].iov_base, false,
&offset);
if (!rb || rb->fd < 0) {
- return;
+ error_setg(errp, "Could not find valid ramblock");
It is a valid ramblock even if rb->fd < 0. It is just "incompatible"
with udmabuf.
+ return VIRTIO_GPU_GUEST_ERROR;
}
list->list[i].memfd = rb->fd;
@@ -56,22 +68,30 @@ static void virtio_gpu_create_udmabuf(struct
virtio_gpu_simple_resource *res)
list->count = res->iov_cnt;
list->flags = UDMABUF_FLAGS_CLOEXEC;
- res->dmabuf_fd = ioctl(udmabuf, UDMABUF_CREATE_LIST, list);
- if (res->dmabuf_fd < 0) {
- warn_report("%s: UDMABUF_CREATE_LIST: %s", __func__,
- strerror(errno));
+ *fd = ioctl(udmabuf, UDMABUF_CREATE_LIST, list);
+ if (*fd < 0) {
+ error_setg_errno(errp, errno, "UDMABUF_CREATE_LIST: ioctl
failed");
+ if (errno == EINVAL || errno == EBADFD) {
+ return VIRTIO_GPU_GUEST_ERROR;
+ }
+ return VIRTIO_GPU_HOST_ERROR;
}
+ return VIRTIO_GPU_NO_ERROR;
}
-static void virtio_gpu_remap_dmabuf(struct
virtio_gpu_simple_resource *res)
+static bool virtio_gpu_remap_dmabuf(struct
virtio_gpu_simple_resource *res,
+ Error **errp)
{
- res->remapped = mmap(NULL, res->blob_size, PROT_READ,
- MAP_SHARED, res->dmabuf_fd, 0);
- if (res->remapped == MAP_FAILED) {
- warn_report("%s: dmabuf mmap failed: %s", __func__,
- strerror(errno));
+ void *map;
+
+ map = mmap(NULL, res->blob_size, PROT_READ, MAP_SHARED,
res->dmabuf_fd, 0);
+ if (map == MAP_FAILED) {
+ error_setg_errno(errp, errno, "dmabuf mmap failed");
res->remapped = NULL;
+ return false;
}
+ res->remapped = map;
+ return true;
}
static void virtio_gpu_destroy_dmabuf(struct
virtio_gpu_simple_resource *res)
@@ -125,19 +145,30 @@ bool virtio_gpu_have_udmabuf(void)
void virtio_gpu_init_dmabuf(struct virtio_gpu_simple_resource *res)
{
+ Error *local_err = NULL;
+ VirtIOGPUErrorType err;
void *pdata = NULL;
+ int fd;
res->dmabuf_fd = -1;
if (res->iov_cnt == 1 &&
res->iov[0].iov_len < 4096) {
pdata = res->iov[0].iov_base;
} else {
- virtio_gpu_create_udmabuf(res);
- if (res->dmabuf_fd < 0) {
+ err = virtio_gpu_create_udmabuf(res, &fd, &local_err);
+ if (err != VIRTIO_GPU_NO_ERROR) {
+ error_prepend(&local_err, "Cannot create dmabuf: ");
+ if (err == VIRTIO_GPU_GUEST_ERROR) {
+ qemu_log_mask(LOG_GUEST_ERROR,
+ "Cannot create dmabuf: incompatible mem\n");
s/mem/memory/
The log is not that long so we can have a full correct spelling.
