This gives management tools like libvirt a chance to open the vfio cdev with privilege and pass FD to qemu.
This way qemu never needs to have privilege to open a VFIO or iommu cdev node. There is no easy way to check if a device is mdev with FD passing, so fail the x-balloon-allowed check unconditionally in this case. There is also no easy way to get BDF as name with FD passing, so we fake a name by VFIO_FD[fd]. Signed-off-by: Zhenzhong Duan <[email protected]> --- hw/vfio/iommufd.c | 12 +++++++---- hw/vfio/pci.c | 53 +++++++++++++++++++++++++++++++++++++++++------ 2 files changed, 55 insertions(+), 10 deletions(-) diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c index e532eed2ac..87f1960eed 100644 --- a/hw/vfio/iommufd.c +++ b/hw/vfio/iommufd.c @@ -343,11 +343,15 @@ static int iommufd_attach_device(char *name, VFIODevice *vbasedev, uint32_t ioas_id; Error *err = NULL; - devfd = vfio_get_devicefd(vbasedev->sysfsdev, errp); - if (devfd < 0) { - return devfd; + if (vbasedev->fd < 0) { + devfd = vfio_get_devicefd(vbasedev->sysfsdev, errp); + if (devfd < 0) { + return devfd; + } + vbasedev->fd = devfd; + } else { + devfd = vbasedev->fd; } - vbasedev->fd = devfd; space = vfio_get_address_space(as); diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c index 9aa6c21200..6429172f30 100644 --- a/hw/vfio/pci.c +++ b/hw/vfio/pci.c @@ -44,6 +44,7 @@ #include "migration/qemu-file.h" #include "linux/iommufd.h" #include "sysemu/iommufd.h" +#include "monitor/monitor.h" #define TYPE_VFIO_PCI_NOHOTPLUG "vfio-pci-nohotplug" @@ -3185,12 +3186,18 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) } #endif - if (!vbasedev->sysfsdev) { + if (vbasedev->fd < 0 && !vbasedev->sysfsdev) { if (!(~vdev->host.domain || ~vdev->host.bus || ~vdev->host.slot || ~vdev->host.function)) { error_setg(errp, "No provided host device"); +#ifdef CONFIG_IOMMUFD + error_append_hint(errp, "Use -device vfio-pci,host=DDDD:BB:DD.F, " + "-device vfio-pci,sysfsdev=PATH_TO_DEVICE " + "or -device vfio-pci,fd=DEVICE_FD\n"); +#else error_append_hint(errp, "Use -device vfio-pci,host=DDDD:BB:DD.F " "or -device vfio-pci,sysfsdev=PATH_TO_DEVICE\n"); +#endif return; } vbasedev->sysfsdev = @@ -3199,13 +3206,28 @@ static void vfio_realize(PCIDevice *pdev, Error **errp) vdev->host.slot, vdev->host.function); } - if (stat(vbasedev->sysfsdev, &st) < 0) { - error_setg_errno(errp, errno, "no such host device"); - error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->sysfsdev); - return; + if (vbasedev->fd < 0) { + if (stat(vbasedev->sysfsdev, &st) < 0) { + error_setg_errno(errp, errno, "no such host device"); + error_prepend(errp, VFIO_MSG_PREFIX, vbasedev->sysfsdev); + return; + } + vbasedev->name = g_path_get_basename(vbasedev->sysfsdev); + } +#ifdef CONFIG_IOMMUFD + else { + if (!vbasedev->iommufd) { + error_setg(errp, "Use FD passing only with iommufd backend"); + return; + } + /* + * Give a name with fd so any function printing out vbasedev->name + * will not break. + */ + vbasedev->name = g_strdup_printf("VFIO_FD%d", vbasedev->fd); } +#endif - vbasedev->name = g_path_get_basename(vbasedev->sysfsdev); vbasedev->ops = &vfio_pci_ops; vbasedev->type = VFIO_DEVICE_TYPE_PCI; vbasedev->dev = DEVICE(vdev); @@ -3574,6 +3596,7 @@ static void vfio_instance_init(Object *obj) vdev->host.bus = ~0U; vdev->host.slot = ~0U; vdev->host.function = ~0U; + vdev->vbasedev.fd = -1; vdev->nv_gpudirect_clique = 0xFF; @@ -3634,6 +3657,21 @@ static Property vfio_pci_dev_properties[] = { DEFINE_PROP_END_OF_LIST(), }; +#ifdef CONFIG_IOMMUFD +static void vfio_pci_set_fd(Object *obj, const char *str, Error **errp) +{ + VFIOPCIDevice *vdev = VFIO_PCI(obj); + int fd = -1; + + fd = monitor_fd_param(monitor_cur(), str, errp); + if (fd == -1) { + error_prepend(errp, "Could not parse remote object fd %s:", str); + return; + } + vdev->vbasedev.fd = fd; +} +#endif + static void vfio_pci_dev_class_init(ObjectClass *klass, void *data) { DeviceClass *dc = DEVICE_CLASS(klass); @@ -3641,6 +3679,9 @@ static void vfio_pci_dev_class_init(ObjectClass *klass, void *data) dc->reset = vfio_pci_reset; device_class_set_props(dc, vfio_pci_dev_properties); +#ifdef CONFIG_IOMMUFD + object_class_property_add_str(klass, "fd", NULL, vfio_pci_set_fd); +#endif dc->desc = "VFIO-based PCI device assignment"; set_bit(DEVICE_CATEGORY_MISC, dc->categories); pdc->realize = vfio_realize; -- 2.34.1
