[PATCH v5 13/29] iommufd/viommu: Introduce IOMMUFD_OBJ_HW_QUEUE and its related struct

Nicolin Chen
2025-05-18T03:49:07Z

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 | 47 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 47 insertions(+)

diff --git a/include/linux/iommufd.h b/include/linux/iommufd.h
index 266ac6805213..923c66ccc15a 100644
--- a/include/linux/iommufd.h
+++ b/include/linux/iommufd.h
@@ -38,6 +38,7 @@ 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
@@ -133,6 +134,24 @@ 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 {
+ /*
+ * The HW does not go through an address translation table but reads the
+ * physical address space directly: iommufd core should pin the physical
+ * pages backing the queue memory that's allocated for the HW QUEUE, and
+ * ensure those physical pages are contiguous in the physical space.
+ */
+ 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
@@ -158,8 +177,18 @@ 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 model; @base_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,
@@ -171,6 +200,10 @@ 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_ucmd *ucmd, 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)
@@ -312,4 +345,18 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu,
} \
ret; \
})
+
+#define iommufd_hw_queue_alloc(ucmd, viommu, drv_struct, member) \
+ ({ \
+ drv_struct *ret; \
+ \
+ static_assert(__same_type(struct iommufd_viommu, *viommu)); \
+ ret = (drv_struct *)__iommufd_object_alloc_ucmd( \
+ ucmd, ret, IOMMUFD_OBJ_HW_QUEUE, member.obj); \
+ if (!IS_ERR(ret)) { \
+ ret->member.viommu = viommu; \
+ ret->member.ictx = viommu->ictx; \
+ } \
+ ret; \
+ })
#endif
--
2.43.0