Re: [PATCH v2 1/4] backends/iommufd: Add a helper to invalidate user-managed HWPT

[Cédric Le Goater]

On 5/30/25 11:35, Zhenzhong Duan wrote:

This helper passes cache invalidation request from guest to invalidate
stage-1 page table cache in host hardware.

Signed-off-by: Nicolin Chen <nicol...@nvidia.com>
Signed-off-by: Zhenzhong Duan <zhenzhong.d...@intel.com>

Reviewed-by: Cédric Le Goater <c...@redhat.com>

Thanks,

C.

---
  include/system/iommufd.h |  4 ++++
  backends/iommufd.c       | 36 ++++++++++++++++++++++++++++++++++++
  backends/trace-events    |  1 +
  3 files changed, 41 insertions(+)

diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index cbab75bfbf..83ab8e1e4c 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -61,6 +61,10 @@ bool iommufd_backend_get_dirty_bitmap(IOMMUFDBackend *be, 
uint32_t hwpt_id,
                                        uint64_t iova, ram_addr_t size,
                                        uint64_t page_size, uint64_t *data,
                                        Error **errp);
+bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, uint32_t id,
+                                      uint32_t data_type, uint32_t entry_len,
+                                      uint32_t *entry_num, void *data,
+                                      Error **errp);

#define TYPE_HOST_IOMMU_DEVICE_IOMMUFD TYPE_HOST_IOMMU_DEVICE "-iommufd"

  #endif
diff --git a/backends/iommufd.c b/backends/iommufd.c
index b73f75cd0b..8bcdb60fe7 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -311,6 +311,42 @@ bool iommufd_backend_get_device_info(IOMMUFDBackend *be, 
uint32_t devid,
      return true;
  }

+bool iommufd_backend_invalidate_cache(IOMMUFDBackend *be, uint32_t id,

+                                      uint32_t data_type, uint32_t entry_len,
+                                      uint32_t *entry_num, void *data,
+                                      Error **errp)
+{
+    int ret, fd = be->fd;
+    uint32_t total_entries = *entry_num;
+    struct iommu_hwpt_invalidate cache = {
+        .size = sizeof(cache),
+        .hwpt_id = id,
+        .data_type = data_type,
+        .entry_len = entry_len,
+        .entry_num = total_entries,
+        .data_uptr = (uintptr_t)data,
+    };
+
+    ret = ioctl(fd, IOMMU_HWPT_INVALIDATE, &cache);
+    trace_iommufd_backend_invalidate_cache(fd, id, data_type, entry_len,
+                                           total_entries, cache.entry_num,
+                                           (uintptr_t)data, ret ? errno : 0);
+    *entry_num = cache.entry_num;
+
+    if (ret) {
+        error_setg_errno(errp, errno, "IOMMU_HWPT_INVALIDATE failed:"
+                         " total %d entries, processed %d entries",
+                         total_entries, cache.entry_num);
+    } else if (total_entries != cache.entry_num) {
+        error_setg(errp, "IOMMU_HWPT_INVALIDATE succeed but with unprocessed"
+                         " entries: total %d entries, processed %d entries."
+                         " Kernel BUG?!", total_entries, cache.entry_num);
+        return false;
+    }
+
+    return !ret;
+}
+
  static int hiod_iommufd_get_cap(HostIOMMUDevice *hiod, int cap, Error **errp)
  {
      HostIOMMUDeviceCaps *caps = &hiod->caps;
diff --git a/backends/trace-events b/backends/trace-events
index 40811a3162..7278214ea5 100644
--- a/backends/trace-events
+++ b/backends/trace-events
@@ -18,3 +18,4 @@ iommufd_backend_alloc_hwpt(int iommufd, uint32_t dev_id, 
uint32_t pt_id, uint32_
  iommufd_backend_free_id(int iommufd, uint32_t id, int ret) " iommufd=%d id=%d 
(%d)"
  iommufd_backend_set_dirty(int iommufd, uint32_t hwpt_id, bool start, int ret) " 
iommufd=%d hwpt=%u enable=%d (%d)"
  iommufd_backend_get_dirty_bitmap(int iommufd, uint32_t hwpt_id, uint64_t iova, uint64_t size, uint64_t page_size, int 
ret) " iommufd=%d hwpt=%u iova=0x%"PRIx64" size=0x%"PRIx64" page_size=0x%"PRIx64" 
(%d)"
+iommufd_backend_invalidate_cache(int iommufd, uint32_t id, uint32_t data_type, uint32_t entry_len, 
uint32_t entry_num, uint32_t done_num, uint64_t data_ptr, int ret) " iommufd=%d id=%u 
data_type=%u entry_len=%u entry_num=%u done_num=%u data_ptr=0x%"PRIx64" (%d)"