[PATCH v4 10/23] iommufd/viommu: Introduce IOMMUFD_OBJ_HW_QUEUE and its related struct

Nicolin Chen
2025-05-09T03:03:41Z

Add IOMMUFD_OBJ_HW_QUEUE with an iommufd_hw_queue structure, representing
a HW-accelerated queue type of IOMMU's physical queue that can be passed
through to a user space VM for direct hardware control, such as:
- NVIDIA's Virtual Command Queue
- AMD vIOMMU's Command Buffer, Event Log Buffer, and PPR Log Buffer

Introduce an allocator iommufd_hw_queue_alloc(). And add a pair of viommu
ops for iommufd to forward user space ioctls to IOMMU drivers.

Given that the first user of this HW QUEUE (tegra241-cmdqv) will need to
ensure the queue memory to be physically contiguous, add a flag property
in iommufd_viommu_ops and IOMMUFD_VIOMMU_FLAG_HW_QUEUE_READS_PA to allow
driver to flag it so that the core will validate the physical pages of a
given guest queue.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
include/linux/iommufd.h | 45 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 45 insertions(+)

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index f6f333eaaae3..0b5bea7286b8 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -37,6 +37,7 @@ enum iommufd_object_type {
IOMMUFD_OBJ_VIOMMU,
IOMMUFD_OBJ_VDEVICE,
IOMMUFD_OBJ_VEVENTQ,
+ IOMMUFD_OBJ_HW_QUEUE,
#ifdef CONFIG_IOMMUFD_TEST
IOMMUFD_OBJ_SELFTEST,
#endif
@@ -112,6 +113,18 @@ struct iommufd_vdevice {
u64 id; /* per-vIOMMU virtual ID */
};

+struct iommufd_hw_queue {
+ struct iommufd_object obj;
+ struct iommufd_ctx *ictx;
+ struct iommufd_viommu *viommu;
+ u64 base_addr; /* in guest physical address space */
+ size_t length;
+};
+
+enum iommufd_viommu_flags {
+ IOMMUFD_VIOMMU_FLAG_HW_QUEUE_READS_PA = 1 << 0,
+};
+
/**
* struct iommufd_viommu_ops - vIOMMU specific operations
* @destroy: Clean up all driver-specific parts of an iommufd_viommu. The memory
@@ -137,8 +150,18 @@ struct iommufd_vdevice {
* @vdevice_destroy: Clean up all driver-specific parts of an iommufd_vdevice.
* The memory of the vDEVICE will be free-ed by iommufd core
* after calling this op
+ * @hw_queue_alloc: Allocate a HW QUEUE object for a HW-accelerated queue given
+ * the @type (must be defined in include/uapi/linux/iommufd.h)
+ * for the @viommu. @index carries the logical HW QUEUE ID per
+ * @viommu in a guest VM, for a multi-queue case; @addr carries
+ * the guest physical base address of the queue memory; @length
+ * carries the size of the queue
+ * @hw_queue_destroy: Clean up all driver-specific parts of an iommufd_hw_queue.
+ * The memory of the HW QUEUE will be free-ed by iommufd core
+ * after calling this op
*/
struct iommufd_viommu_ops {
+ u32 flags;
void (*destroy)(struct iommufd_viommu *viommu);
struct iommu_domain *(*alloc_domain_nested)(
struct iommufd_viommu *viommu, u32 flags,
@@ -149,6 +172,10 @@ struct iommufd_viommu_ops {
struct device *dev,
u64 virt_id);
void (*vdevice_destroy)(struct iommufd_vdevice *vdev);
+ struct iommufd_hw_queue *(*hw_queue_alloc)(
+ struct iommufd_viommu *viommu, unsigned int type, u32 index,
+ u64 base_addr, size_t length);
+ void (*hw_queue_destroy)(struct iommufd_hw_queue *hw_queue);
};

#if IS_ENABLED(CONFIG_IOMMUFD)
@@ -292,6 +319,24 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
ret; \
})

+#define iommufd_hw_queue_alloc(viommu, drv_struct, member) \
+ ({ \
+ drv_struct *ret; \
+ \
+ static_assert(__same_type(struct iommufd_viommu, *viommu)); \
+ static_assert(__same_type(struct iommufd_hw_queue, \
+ ((drv_struct *)NULL)->member)); \
+ static_assert(offsetof(drv_struct, member.obj) == 0); \
+ ret = (drv_struct *)_iommufd_object_alloc( \
+ viommu->ictx, sizeof(drv_struct), \
+ IOMMUFD_OBJ_HW_QUEUE); \
+ if (!IS_ERR(ret)) { \
+ ret->member.viommu = viommu; \
+ ret->member.ictx = viommu->ictx; \
+ } \
+ ret; \
+ })
+
/* Helper for IOMMU driver to destroy structures created by allocators above */
#define iommufd_struct_destroy(drv_struct, member) \
({ \
--
2.43.0