From: Nicolin Chen <nicolinc@nvidia.com>

Add a backend helper to mmap hardware MMIO regions exposed via iommufd for
a vIOMMU instance. This allows user space to access HW-accelerated MMIO
pages provided by the vIOMMU.

The caller is responsible for unmapping the returned region.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
---
 backends/iommufd.c       | 24 ++++++++++++++++++++++++
 backends/trace-events    |  1 +
 include/system/iommufd.h |  4 ++++
 3 files changed, 29 insertions(+)

diff --git a/backends/iommufd.c b/backends/iommufd.c
index a644763239..015e5249d6 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -575,6 +575,30 @@ bool iommufd_backend_alloc_hw_queue(IOMMUFDBackend *be, uint32_t viommu_id,
     return true;
 }
 
+/*
+ * Helper to mmap HW MMIO regions exposed via iommufd for a vIOMMU instance.
+ * The caller is responsible for unmapping the mapped region.
+ */
+bool iommufd_backend_viommu_mmap(IOMMUFDBackend *be, uint32_t viommu_id,
+                                 uint64_t size, off_t offset, void **out_ptr,
+                                 Error **errp)
+{
+    g_assert(viommu_id);
+    g_assert(out_ptr);
+
+    *out_ptr = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, be->fd,
+                   offset);
+    if (*out_ptr == MAP_FAILED) {
+        error_setg_errno(errp, errno, "failed to mmap (size=0x%" PRIx64
+                         " offset=0x%" PRIx64 ") for viommu (id=%d)",
+                         size, offset, viommu_id);
+        return false;
+    }
+
+    trace_iommufd_backend_viommu_mmap(be->fd, viommu_id, size, offset);
+    return true;
+}
+
 bool host_iommu_device_iommufd_attach_hwpt(HostIOMMUDeviceIOMMUFD *idev,
                                            uint32_t hwpt_id, Error **errp)
 {
diff --git a/backends/trace-events b/backends/trace-events
index a22ad30e55..046f453caa 100644
--- a/backends/trace-events
+++ b/backends/trace-events
@@ -25,3 +25,4 @@ iommufd_backend_alloc_viommu(int iommufd, uint32_t dev_id, uint32_t type, uint32
 iommufd_backend_alloc_vdev(int iommufd, uint32_t dev_id, uint32_t viommu_id, uint64_t virt_id, uint32_t vdev_id, int ret) " iommufd=%d dev_id=%u viommu_id=%u virt_id=0x%"PRIx64" vdev_id=%u (%d)"
 iommufd_viommu_alloc_eventq(int iommufd, uint32_t viommu_id, uint32_t type, uint32_t veventq_id, uint32_t veventq_fd, int ret) " iommufd=%d viommu_id=%u type=%u veventq_id=%u veventq_fd=%u (%d)"
 iommufd_backend_alloc_hw_queue(int iommufd, uint32_t viommu_id, uint32_t vqueue_type, uint32_t index, uint64_t addr, uint64_t size, uint32_t vqueue_id, int ret) " iommufd=%d viommu_id=%u vqueue_type=%u index=%u addr=0x%"PRIx64" size=0x%"PRIx64" vqueue_id=%u (%d)"
+iommufd_backend_viommu_mmap(int iommufd, uint32_t viommu_id, uint64_t size, uint64_t offset) " iommufd=%d viommu_id=%u size=0x%"PRIx64" offset=0x%"PRIx64
diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index 9b8602a558..e3905c9a40 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -110,6 +110,10 @@ bool iommufd_backend_alloc_hw_queue(IOMMUFDBackend *be, uint32_t viommu_id,
                                     uint64_t addr, uint64_t length,
                                     uint32_t *out_hw_queue_id, Error **errp);
 
+bool iommufd_backend_viommu_mmap(IOMMUFDBackend *be, uint32_t viommu_id,
+                                 uint64_t size, off_t offset, void **out_ptr,
+                                 Error **errp);
+
 bool iommufd_backend_set_dirty_tracking(IOMMUFDBackend *be, uint32_t hwpt_id,
                                         bool start, Error **errp);
 bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, uint32_t hwpt_id,
-- 
2.43.0