Re: [PATCH V3 28/42] backends/iommufd: iommufd_backend_map_file_dma

[Steven Sistare]

On 5/19/2025 11:51 AM, Steven Sistare wrote:

On 5/16/2025 4:26 AM, Duan, Zhenzhong wrote:

-----Original Message-----
From: Steve Sistare <steven.sist...@oracle.com>
Subject: [PATCH V3 28/42] backends/iommufd:
iommufd_backend_map_file_dma

Define iommufd_backend_map_file_dma to implement IOMMU_IOAS_MAP_FILE.
This will be called as a substitute for iommufd_backend_map_dma, so
the error conditions for BARs are copied as-is from that function.

Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
---
backends/iommufd.c       | 36 ++++++++++++++++++++++++++++++++++++
backends/trace-events    |  1 +
include/system/iommufd.h |  3 +++
3 files changed, 40 insertions(+)

diff --git a/backends/iommufd.c b/backends/iommufd.c
index b73f75c..5c1958f 100644
--- a/backends/iommufd.c
+++ b/backends/iommufd.c
@@ -172,6 +172,42 @@ int iommufd_backend_map_dma(IOMMUFDBackend
*be, uint32_t ioas_id, hwaddr iova,
     return ret;
}

+int iommufd_backend_map_file_dma(IOMMUFDBackend *be, uint32_t ioas_id,
+                                 hwaddr iova, ram_addr_t size,
+                                 int mfd, unsigned long start, bool readonly)
+{
+    int ret, fd = be->fd;
+    struct iommu_ioas_map_file map = {
+        .size = sizeof(map),
+        .flags = IOMMU_IOAS_MAP_READABLE |
+                 IOMMU_IOAS_MAP_FIXED_IOVA,
+        .ioas_id = ioas_id,
+        .fd = mfd,
+        .start = start,
+        .iova = iova,
+        .length = size,
+    };
+
+    if (!readonly) {
+        map.flags |= IOMMU_IOAS_MAP_WRITEABLE;
+    }
+
+    ret = ioctl(fd, IOMMU_IOAS_MAP_FILE, &map);
+    trace_iommufd_backend_map_file_dma(fd, ioas_id, iova, size, mfd, start,
+                                       readonly, ret);
+    if (ret) {
+        ret = -errno;
+
+        /* TODO: Not support mapping hardware PCI BAR region for now. */
+        if (errno == EFAULT) {
+            warn_report("IOMMU_IOAS_MAP_FILE failed: %m, PCI BAR?");
+        } else {
+            error_report("IOMMU_IOAS_MAP_FILE failed: %m");

No need to print error here as caller does the same thing.

OK.  I was copying iommufd_backend_map_dma, but I see it has recently
dropped the error_report.

If I delete the error_report line, can I add your RB?

- Steve

+        }
+    }
+    return ret;
+}
+
int iommufd_backend_unmap_dma(IOMMUFDBackend *be, uint32_t ioas_id,
                               hwaddr iova, ram_addr_t size)
{
diff --git a/backends/trace-events b/backends/trace-events
index 40811a3..f478e18 100644
--- a/backends/trace-events
+++ b/backends/trace-events
@@ -11,6 +11,7 @@ iommufd_backend_connect(int fd, bool owned, uint32_t
users) "fd=%d owned=%d user
iommufd_backend_disconnect(int fd, uint32_t users) "fd=%d users=%d"
iommu_backend_set_fd(int fd) "pre-opened /dev/iommu fd=%d"
iommufd_backend_map_dma(int iommufd, uint32_t ioas, uint64_t iova, uint64_t
size, void *vaddr, bool readonly, int ret) " iommufd=%d ioas=%d
iova=0x%"PRIx64" size=0x%"PRIx64" addr=%p readonly=%d (%d)"
+iommufd_backend_map_file_dma(int iommufd, uint32_t ioas, uint64_t iova,
uint64_t size, int fd, unsigned long start, bool readonly, int ret) " iommufd=%d
ioas=%d iova=0x%"PRIx64" size=0x%"PRIx64" fd=%d start=%ld readonly=%d
(%d)"
iommufd_backend_unmap_dma_non_exist(int iommufd, uint32_t ioas, uint64_t
iova, uint64_t size, int ret) " Unmap nonexistent mapping: iommufd=%d ioas=%d
iova=0x%"PRIx64" size=0x%"PRIx64" (%d)"
iommufd_backend_unmap_dma(int iommufd, uint32_t ioas, uint64_t iova,
uint64_t size, int ret) " iommufd=%d ioas=%d iova=0x%"PRIx64"
size=0x%"PRIx64" (%d)"
iommufd_backend_alloc_ioas(int iommufd, uint32_t ioas) " iommufd=%d
ioas=%d"
diff --git a/include/system/iommufd.h b/include/system/iommufd.h
index cbab75b..ac700b8 100644
--- a/include/system/iommufd.h
+++ b/include/system/iommufd.h
@@ -43,6 +43,9 @@ void iommufd_backend_disconnect(IOMMUFDBackend
*be);
bool iommufd_backend_alloc_ioas(IOMMUFDBackend *be, uint32_t *ioas_id,
                                 Error **errp);
void iommufd_backend_free_id(IOMMUFDBackend *be, uint32_t id);
+int iommufd_backend_map_file_dma(IOMMUFDBackend *be, uint32_t ioas_id,
+                                 hwaddr iova, ram_addr_t size, int fd,
+                                 unsigned long start, bool readonly);
int iommufd_backend_map_dma(IOMMUFDBackend *be, uint32_t ioas_id,
hwaddr iova,
                             ram_addr_t size, void *vaddr, bool readonly);
int iommufd_backend_unmap_dma(IOMMUFDBackend *be, uint32_t ioas_id,
--
1.8.3.1