[PATCH v2 10/22] iommufd/viommmu: Add IOMMUFD_CMD_VCMDQ_ALLOC ioctl

Nicolin Chen
2025-04-26T05:59:18Z

Introduce a new IOMMUFD_CMD_VCMDQ_ALLOC ioctl for user space to allocate
a vCMDQ for a vIOMMU object. Simply increase the refcount of the vIOMMU.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
drivers/iommu/iommufd/iommufd_private.h | 2 +
include/uapi/linux/iommufd.h | 41 +++++++++++
drivers/iommu/iommufd/main.c | 6 ++
drivers/iommu/iommufd/viommu.c | 94 +++++++++++++++++++++++++
4 files changed, 143 insertions(+)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 79160b039bc7..b974c207ae8a 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -611,6 +611,8 @@ int iommufd_viommu_alloc_ioctl(struct iommufd_ucmd *ucmd);
void iommufd_viommu_destroy(struct iommufd_object *obj);
int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd);
void iommufd_vdevice_destroy(struct iommufd_object *obj);
+int iommufd_vcmdq_alloc_ioctl(struct iommufd_ucmd *ucmd);
+void iommufd_vcmdq_destroy(struct iommufd_object *obj);

#ifdef CONFIG_IOMMUFD_TEST
int iommufd_test(struct iommufd_ucmd *ucmd);
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index cc90299a08d9..06a763fda47f 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -56,6 +56,7 @@ enum {
IOMMUFD_CMD_VDEVICE_ALLOC = 0x91,
IOMMUFD_CMD_IOAS_CHANGE_PROCESS = 0x92,
IOMMUFD_CMD_VEVENTQ_ALLOC = 0x93,
+ IOMMUFD_CMD_VCMDQ_ALLOC = 0x94,
};

/**
@@ -1147,4 +1148,44 @@ struct iommu_veventq_alloc {
__u32 __reserved;
};
#define IOMMU_VEVENTQ_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VEVENTQ_ALLOC)
+
+/**
+ * enum iommu_vcmdq_type - Virtual Command Queue Type
+ * @IOMMU_VCMDQ_TYPE_DEFAULT: Reserved for future use
+ */
+enum iommu_vcmdq_type {
+ IOMMU_VCMDQ_TYPE_DEFAULT = 0,
+};
+
+/**
+ * struct iommu_vcmdq_alloc - ioctl(IOMMU_VCMDQ_ALLOC)
+ * @size: sizeof(struct iommu_vcmdq_alloc)
+ * @flags: Must be 0
+ * @viommu_id: Virtual IOMMU ID to associate the virtual command queue with
+ * @type: One of enum iommu_vcmdq_type
+ * @index: The logical index to the virtual command queue per virtual IOMMU, for
+ * a multi-queue model
+ * @out_vcmdq_id: The ID of the new virtual command queue
+ * @addr: Base address of the queue memory in the guest physical address space
+ * @length: Length of the queue memory in the guest physical address space
+ *
+ * Allocate a virtual command queue object for a vIOMMU-specific HW-accelerated
+ * feature that can access a guest queue memory described by @addr and @length.
+ * It's suggested for VMM to back the queue memory using a single huge page with
+ * a proper alignment for its contiguity in the host physical address space. The
+ * call will fail, if the queue memory is not contiguous in the physical address
+ * space. Upon success, its underlying physical pages will be pinned to prevent
+ * VMM from unmapping them in the IOAS, until the virtual CMDQ gets destroyed.
+ */
+struct iommu_vcmdq_alloc {
+ __u32 size;
+ __u32 flags;
+ __u32 viommu_id;
+ __u32 type;
+ __u32 index;
+ __u32 out_vcmdq_id;
+ __aligned_u64 addr;
+ __aligned_u64 length;
+};
+#define IOMMU_VCMDQ_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_VCMDQ_ALLOC)
#endif
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 2b9ee9b4a424..ac51d5cfaa61 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -303,6 +303,7 @@ union ucmd_buffer {
struct iommu_ioas_map map;
struct iommu_ioas_unmap unmap;
struct iommu_option option;
+ struct iommu_vcmdq_alloc vcmdq;
struct iommu_vdevice_alloc vdev;
struct iommu_veventq_alloc veventq;
struct iommu_vfio_ioas vfio_ioas;
@@ -358,6 +359,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct iommu_ioas_unmap,
length),
IOCTL_OP(IOMMU_OPTION, iommufd_option, struct iommu_option, val64),
+ IOCTL_OP(IOMMU_VCMDQ_ALLOC, iommufd_vcmdq_alloc_ioctl,
+ struct iommu_vcmdq_alloc, length),
IOCTL_OP(IOMMU_VDEVICE_ALLOC, iommufd_vdevice_alloc_ioctl,
struct iommu_vdevice_alloc, virt_id),
IOCTL_OP(IOMMU_VEVENTQ_ALLOC, iommufd_veventq_alloc,
@@ -501,6 +504,9 @@ static const struct iommufd_object_ops iommufd_object_ops[] = {
[IOMMUFD_OBJ_IOAS] = {
.destroy = iommufd_ioas_destroy,
},
+ [IOMMUFD_OBJ_VCMDQ] = {
+ .destroy = iommufd_vcmdq_destroy,
+ },
[IOMMUFD_OBJ_VDEVICE] = {
.destroy = iommufd_vdevice_destroy,
},
diff --git a/drivers/iommu/iommufd/viommu.c b/drivers/iommu/iommufd/viommu.c
index a65153458a26..02a111710ffe 100644
--- a/drivers/iommu/iommufd/viommu.c
+++ b/drivers/iommu/iommufd/viommu.c
@@ -170,3 +170,97 @@ int iommufd_vdevice_alloc_ioctl(struct iommufd_ucmd *ucmd)
iommufd_put_object(ucmd->ictx, &viommu->obj);
return rc;
}
+
+void iommufd_vcmdq_destroy(struct iommufd_object *obj)
+{
+ struct iommufd_vcmdq *vcmdq =
+ container_of(obj, struct iommufd_vcmdq, obj);
+ struct iommufd_viommu *viommu = vcmdq->viommu;
+
+ if (viommu->ops->vcmdq_destroy)
+ viommu->ops->vcmdq_destroy(vcmdq);
+ iopt_unpin_pages(&viommu->hwpt->ioas->iopt, vcmdq->addr, vcmdq->length);
+ refcount_dec(&viommu->obj.users);
+}
+
+int iommufd_vcmdq_alloc_ioctl(struct iommufd_ucmd *ucmd)
+{
+ struct iommu_vcmdq_alloc *cmd = ucmd->cmd;
+ struct iommufd_viommu *viommu;
+ struct iommufd_vcmdq *vcmdq;
+ struct page **pages;
+ int max_npages, i;
+ dma_addr_t end;
+ int rc;
+
+ if (cmd->flags || cmd->type == IOMMU_VCMDQ_TYPE_DEFAULT)
+ return -EOPNOTSUPP;
+ if (!cmd->addr || !cmd->length)
+ return -EINVAL;
+ if (check_add_overflow(cmd->addr, cmd->length - 1, &end))
+ return -EOVERFLOW;
+
+ max_npages = DIV_ROUND_UP(cmd->length, PAGE_SIZE);
+ pages = kcalloc(max_npages, sizeof(*pages), GFP_KERNEL);
+ if (!pages)
+ return -ENOMEM;
+
+ viommu = iommufd_get_viommu(ucmd, cmd->viommu_id);
+ if (IS_ERR(viommu)) {
+ rc = PTR_ERR(viommu);
+ goto out_free;
+ }
+
+ if (!viommu->ops || !viommu->ops->vcmdq_alloc) {
+ rc = -EOPNOTSUPP;
+ goto out_put_viommu;
+ }
+
+ /* Quick test on the base address */
+ if (!iommu_iova_to_phys(viommu->hwpt->common.domain, cmd->addr)) {
+ rc = -ENXIO;
+ goto out_put_viommu;
+ }
+
+ /* The underlying physical pages must be pinned in the IOAS */
+ rc = iopt_pin_pages(&viommu->hwpt->ioas->iopt, cmd->addr, cmd->length,
+ pages, 0);
+ if (rc)
+ goto out_put_viommu;
+
+ /* Validate if the underlying physical pages are contiguous */
+ for (i = 1; i < max_npages && pages[i]; i++) {
+ if (page_to_pfn(pages[i]) == page_to_pfn(pages[i - 1]) + 1)
+ continue;
+ rc = -EFAULT;
+ goto out_unpin;
+ }
+
+ vcmdq = viommu->ops->vcmdq_alloc(viommu, cmd->type, cmd->index,
+ cmd->addr, cmd->length);
+ if (IS_ERR(vcmdq)) {
+ rc = PTR_ERR(vcmdq);
+ goto out_unpin;
+ }
+
+ vcmdq->viommu = viommu;
+ refcount_inc(&viommu->obj.users);
+ vcmdq->addr = cmd->addr;
+ vcmdq->ictx = ucmd->ictx;
+ vcmdq->length = cmd->length;
+ cmd->out_vcmdq_id = vcmdq->obj.id;
+ rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+ if (rc)
+ iommufd_object_abort_and_destroy(ucmd->ictx, &vcmdq->obj);
+ else
+ iommufd_object_finalize(ucmd->ictx, &vcmdq->obj);
+ goto out_put_viommu;
+
+out_unpin:
+ iopt_unpin_pages(&viommu->hwpt->ioas->iopt, cmd->addr, cmd->length);
+out_put_viommu:
+ iommufd_put_object(ucmd->ictx, &viommu->obj);
+out_free:
+ kfree(pages);
+ return rc;
+}
--
2.43.0