[RFC v4 03/21] vfio-user: add container IO ops vector

From: John Johnson <john.g.johnson@oracle.com>
To: qemu-devel@nongnu.org
Subject: [RFC v4 03/21] vfio-user: add container IO ops vector
Date: Tue, 11 Jan 2022 16:43:39 -0800	[thread overview]
Message-ID: <58534cabf2ca1891f7b8a4c09d8ec7e08bcdd695.1641584316.git.john.g.johnson@oracle.com> (raw)
In-Reply-To: <cover.1641584316.git.john.g.johnson@oracle.com>

Used for communication with VFIO driver
(prep work for vfio-user, which will communicate over a socket)

Signed-off-by: John G Johnson <john.g.johnson@oracle.com>
---
 include/hw/vfio/vfio-common.h |  33 +++++++++++
 hw/vfio/common.c              | 126 ++++++++++++++++++++++++++++--------------
 2 files changed, 117 insertions(+), 42 deletions(-)

diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 8af11b0..2761a62 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -75,6 +75,7 @@ typedef struct VFIOAddressSpace {
 } VFIOAddressSpace;
 
 struct VFIOGroup;
+typedef struct VFIOContIO VFIOContIO;
 
 typedef struct VFIOContainer {
     VFIOAddressSpace *space;
@@ -83,6 +84,7 @@ typedef struct VFIOContainer {
     MemoryListener prereg_listener;
     unsigned iommu_type;
     Error *error;
+    VFIOContIO *io_ops;
     bool initialized;
     bool dirty_pages_supported;
     uint64_t dirty_pgsizes;
@@ -154,6 +156,37 @@ struct VFIODeviceOps {
     int (*vfio_load_config)(VFIODevice *vdev, QEMUFile *f);
 };
 
+#ifdef CONFIG_LINUX
+
+/*
+ * The next 2 ops vectors are how Devices and Containers
+ * communicate with the server.  The default option is
+ * through ioctl() to the kernel VFIO driver, but vfio-user
+ * can use a socket to a remote process.
+ */
+
+struct VFIOContIO {
+    int (*dma_map)(VFIOContainer *container,
+                   struct vfio_iommu_type1_dma_map *map);
+    int (*dma_unmap)(VFIOContainer *container,
+                     struct vfio_iommu_type1_dma_unmap *unmap,
+                     struct vfio_bitmap *bitmap);
+    int (*dirty_bitmap)(VFIOContainer *container,
+                        struct vfio_iommu_type1_dirty_bitmap *bitmap,
+                        struct vfio_iommu_type1_dirty_bitmap_get *range);
+};
+
+#define CONT_DMA_MAP(cont, map) \
+    ((cont)->io_ops->dma_map((cont), (map)))
+#define CONT_DMA_UNMAP(cont, unmap, bitmap) \
+    ((cont)->io_ops->dma_unmap((cont), (unmap), (bitmap)))
+#define CONT_DIRTY_BITMAP(cont, bitmap, range) \
+    ((cont)->io_ops->dirty_bitmap((cont), (bitmap), (range)))
+
+extern VFIOContIO vfio_cont_io_ioctl;
+
+#endif /* CONFIG_LINUX */
+
 typedef struct VFIOGroup {
     int fd;
     int groupid;
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 080046e..dbf23c0 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -431,12 +431,12 @@ static int vfio_dma_unmap_bitmap(VFIOContainer *container,
         goto unmap_exit;
     }
 
-    ret = ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap);
+    ret = CONT_DMA_UNMAP(container, unmap, bitmap);
     if (!ret) {
         cpu_physical_memory_set_dirty_lebitmap((unsigned long *)bitmap->data,
                 iotlb->translated_addr, pages);
     } else {
-        error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %m");
+        error_report("VFIO_UNMAP_DMA with DIRTY_BITMAP : %s", strerror(-ret));
     }
 
     g_free(bitmap->data);
@@ -464,30 +464,7 @@ static int vfio_dma_unmap(VFIOContainer *container,
         return vfio_dma_unmap_bitmap(container, iova, size, iotlb);
     }
 
-    while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
-        /*
-         * The type1 backend has an off-by-one bug in the kernel (71a7d3d78e3c
-         * v4.15) where an overflow in its wrap-around check prevents us from
-         * unmapping the last page of the address space.  Test for the error
-         * condition and re-try the unmap excluding the last page.  The
-         * expectation is that we've never mapped the last page anyway and this
-         * unmap request comes via vIOMMU support which also makes it unlikely
-         * that this page is used.  This bug was introduced well after type1 v2
-         * support was introduced, so we shouldn't need to test for v1.  A fix
-         * is queued for kernel v5.0 so this workaround can be removed once
-         * affected kernels are sufficiently deprecated.
-         */
-        if (errno == EINVAL && unmap.size && !(unmap.iova + unmap.size) &&
-            container->iommu_type == VFIO_TYPE1v2_IOMMU) {
-            trace_vfio_dma_unmap_overflow_workaround();
-            unmap.size -= 1ULL << ctz64(container->pgsizes);
-            continue;
-        }
-        error_report("VFIO_UNMAP_DMA failed: %s", strerror(errno));
-        return -errno;
-    }
-
-    return 0;
+    return CONT_DMA_UNMAP(container, &unmap, NULL);
 }
 
 static int vfio_dma_map(VFIOContainer *container, hwaddr iova,
@@ -500,24 +477,18 @@ static int vfio_dma_map(VFIOContainer *container, hwaddr iova,
         .iova = iova,
         .size = size,
     };
+    int ret;
 
     if (!readonly) {
         map.flags |= VFIO_DMA_MAP_FLAG_WRITE;
     }
 
-    /*
-     * Try the mapping, if it fails with EBUSY, unmap the region and try
-     * again.  This shouldn't be necessary, but we sometimes see it in
-     * the VGA ROM space.
-     */
-    if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0 ||
-        (errno == EBUSY && vfio_dma_unmap(container, iova, size, NULL) == 0 &&
-         ioctl(container->fd, VFIO_IOMMU_MAP_DMA, &map) == 0)) {
-        return 0;
-    }
+    ret = CONT_DMA_MAP(container, &map);
 
-    error_report("VFIO_MAP_DMA failed: %s", strerror(errno));
-    return -errno;
+    if (ret < 0) {
+        error_report("VFIO_MAP_DMA failed: %s", strerror(-ret));
+    }
+    return ret;
 }
 
 static void vfio_host_win_add(VFIOContainer *container,
@@ -1230,10 +1201,10 @@ static void vfio_set_dirty_page_tracking(VFIOContainer *container, bool start)
         dirty.flags = VFIO_IOMMU_DIRTY_PAGES_FLAG_STOP;
     }
 
-    ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, &dirty);
+    ret = CONT_DIRTY_BITMAP(container, &dirty, NULL);
     if (ret) {
         error_report("Failed to set dirty tracking flag 0x%x errno: %d",
-                     dirty.flags, errno);
+                     dirty.flags, -ret);
     }
 }
 
@@ -1283,11 +1254,11 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
         goto err_out;
     }
 
-    ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, dbitmap);
+    ret = CONT_DIRTY_BITMAP(container, dbitmap, range);
     if (ret) {
         error_report("Failed to get dirty bitmap for iova: 0x%"PRIx64
                 " size: 0x%"PRIx64" err: %d", (uint64_t)range->iova,
-                (uint64_t)range->size, errno);
+                (uint64_t)range->size, -ret);
         goto err_out;
     }
 
@@ -2058,6 +2029,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
     container->error = NULL;
     container->dirty_pages_supported = false;
     container->dma_max_mappings = 0;
+    container->io_ops = &vfio_cont_io_ioctl;
     QLIST_INIT(&container->giommu_list);
     QLIST_INIT(&container->hostwin_list);
     QLIST_INIT(&container->vrdl_list);
@@ -2594,3 +2566,73 @@ int vfio_eeh_as_op(AddressSpace *as, uint32_t op)
     }
     return vfio_eeh_container_op(container, op);
 }
+
+/*
+ * Traditional ioctl() based io_ops
+ */
+
+static int vfio_io_dma_map(VFIOContainer *container,
+                           struct vfio_iommu_type1_dma_map *map)
+{
+
+    /*
+     * Try the mapping, if it fails with EBUSY, unmap the region and try
+     * again.  This shouldn't be necessary, but we sometimes see it in
+     * the VGA ROM space.
+     */
+    if (ioctl(container->fd, VFIO_IOMMU_MAP_DMA, map) == 0 ||
+        (errno == EBUSY &&
+         vfio_dma_unmap(container, map->iova, map->size, NULL) == 0 &&
+         ioctl(container->fd, VFIO_IOMMU_MAP_DMA, map) == 0)) {
+        return 0;
+    }
+    return -errno;
+}
+
+static int vfio_io_dma_unmap(VFIOContainer *container,
+                             struct vfio_iommu_type1_dma_unmap *unmap,
+                             struct vfio_bitmap *bitmap)
+{
+
+    while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, unmap)) {
+        /*
+         * The type1 backend has an off-by-one bug in the kernel (71a7d3d78e3c
+         * v4.15) where an overflow in its wrap-around check prevents us from
+         * unmapping the last page of the address space.  Test for the error
+         * condition and re-try the unmap excluding the last page.  The
+         * expectation is that we've never mapped the last page anyway and this
+         * unmap request comes via vIOMMU support which also makes it unlikely
+         * that this page is used.  This bug was introduced well after type1 v2
+         * support was introduced, so we shouldn't need to test for v1.  A fix
+         * is queued for kernel v5.0 so this workaround can be removed once
+         * affected kernels are sufficiently deprecated.
+         */
+        if (errno == EINVAL && unmap->size && !(unmap->iova + unmap->size) &&
+            container->iommu_type == VFIO_TYPE1v2_IOMMU) {
+            trace_vfio_dma_unmap_overflow_workaround();
+            unmap->size -= 1ULL << ctz64(container->pgsizes);
+            continue;
+        }
+        error_report("VFIO_UNMAP_DMA failed: %s", strerror(errno));
+        return -errno;
+    }
+
+    return 0;
+}
+
+static int vfio_io_dirty_bitmap(VFIOContainer *container,
+                                struct vfio_iommu_type1_dirty_bitmap *bitmap,
+                                struct vfio_iommu_type1_dirty_bitmap_get *range)
+{
+    int ret;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, bitmap);
+
+    return ret < 0 ? -errno : ret;
+}
+
+VFIOContIO vfio_cont_io_ioctl = {
+    .dma_map = vfio_io_dma_map,
+    .dma_unmap = vfio_io_dma_unmap,
+    .dirty_bitmap = vfio_io_dirty_bitmap,
+};
-- 
1.8.3.1


