On 3/18/26 19:06, Pierrick Bouvier wrote:
In case current kernel does not support /dev/iommu, qemu will probably
fail first because /sys/bus/pci/devices/*/vfio-dev/ is not present,
since QEMU opens it before /dev/iommu.
Instead, report an error directly when completing an iommufd object, to
inform user that kernel does not support it, with a hint about missing
CONFIG_IOMMUFD. We can't do this from initialize as there is no way to
return an error, and we don't want to abort at this step.
Reviewed-by: Philippe Mathieu-Daudé <[email protected]>
Signed-off-by: Pierrick Bouvier <[email protected]>
---
backends/iommufd.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/backends/iommufd.c b/backends/iommufd.c
index acfab907c03..2c3ca23ca0f 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -72,6 +72,12 @@ static bool iommufd_backend_can_be_deleted(UserCreatable *uc)
static void iommufd_backend_complete(UserCreatable *uc, Error **errp)
{
+ if (!g_file_test("/dev/iommu", G_FILE_TEST_EXISTS)) {
+ error_setg(errp, "/dev/iommu does not exist"
+ " (is your kernel config missing CONFIG_IOMMUFD?)");
+ return;
+ }
+
IOMMUFDBackend *be = IOMMUFD_BACKEND(uc);
const char *name = iommufd_fd_name(be);
Reviewed-by: Cédric Le Goater <[email protected]>
Thanks,
C.
