vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2)

New VFIO_SPAPR_TCE_v2_IOMMU type supports dynamic DMA window management.
This adds ability to VFIO common code to dynamically allocate/remove
DMA windows in the host kernel when new VFIO container is added/removed.

This adds a helper to vfio_listener_region_add which makes
VFIO_IOMMU_SPAPR_TCE_CREATE ioctl and adds just created IOMMU into
the host IOMMU list; the opposite action is taken in
vfio_listener_region_del.

When creating a new window, this uses heuristic to decide on the TCE table
levels number.

This should cause no guest visible change in behavior.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
[dwg: Added some casts to prevent printf() warnings on certain targets
 where the kernel headers' __u64 doesn't match uint64_t or PRIx64]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/vfio/common.c

@@ -265,6 +265,21 @@ static void vfio_host_win_add(VFIOContainer *container,
     QLIST_INSERT_HEAD(&container->hostwin_list, hostwin, hostwin_next);
 }
 
+static int vfio_host_win_del(VFIOContainer *container, hwaddr min_iova,
+                             hwaddr max_iova)
+{
+    VFIOHostDMAWindow *hostwin;
+
+    QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
+        if (hostwin->min_iova == min_iova && hostwin->max_iova == max_iova) {
+            QLIST_REMOVE(hostwin, hostwin_next);
+            return 0;
+        }
+    }
+
+    return -1;
+}
+
 static bool vfio_listener_skipped_section(MemoryRegionSection *section)
 {
     return (!memory_region_is_ram(section->mr) &&
@@ -380,6 +395,31 @@ static void vfio_listener_region_add(MemoryListener *listener,
     }
     end = int128_get64(int128_sub(llend, int128_one()));
 
+    if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
+        VFIOHostDMAWindow *hostwin;
+        hwaddr pgsize = 0;
+
+        /* For now intersections are not allowed, we may relax this later */
+        QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
+            if (ranges_overlap(hostwin->min_iova,
+                               hostwin->max_iova - hostwin->min_iova + 1,
+                               section->offset_within_address_space,
+                               int128_get64(section->size))) {
+                ret = -1;
+                goto fail;
+            }
+        }
+
+        ret = vfio_spapr_create_window(container, section, &pgsize);
+        if (ret) {
+            goto fail;
+        }
+
+        vfio_host_win_add(container, section->offset_within_address_space,
+                          section->offset_within_address_space +
+                          int128_get64(section->size) - 1, pgsize);
+    }
+
     hostwin_found = false;
     QLIST_FOREACH(hostwin, &container->hostwin_list, hostwin_next) {
         if (hostwin->min_iova <= iova && end <= hostwin->max_iova) {
@@ -523,6 +563,18 @@ static void vfio_listener_region_del(MemoryListener *listener,
                      "0x%"HWADDR_PRIx") = %d (%m)",
                      container, iova, int128_get64(llsize), ret);
     }
+
+    if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
+        vfio_spapr_remove_window(container,
+                                 section->offset_within_address_space);
+        if (vfio_host_win_del(container,
+                              section->offset_within_address_space,
+                              section->offset_within_address_space +
+                              int128_get64(section->size) - 1) < 0) {
+            hw_error("%s: Cannot delete missing window at %"HWADDR_PRIx,
+                     __func__, section->offset_within_address_space);
+        }
+    }
 }
 
 static const MemoryListener vfio_memory_listener = {
@@ -961,11 +1013,6 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
             }
         }
 
-        /*
-         * This only considers the host IOMMU's 32-bit window.  At
-         * some point we need to add support for the optional 64-bit
-         * window and dynamic windows
-         */
         info.argsz = sizeof(info);
         ret = ioctl(fd, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &info);
         if (ret) {
@@ -977,11 +1024,24 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
             goto free_container_exit;
         }
 
+        if (v2) {
+            /*
+             * There is a default window in just created container.
+             * To make region_add/del simpler, we better remove this
+             * window now and let those iommu_listener callbacks
+             * create/remove them when needed.
+             */
+            ret = vfio_spapr_remove_window(container, info.dma32_window_start);
+            if (ret) {
+                goto free_container_exit;
+            }
+        } else {
             /* The default table uses 4K pages */
             vfio_host_win_add(container, info.dma32_window_start,
                               info.dma32_window_start +
                               info.dma32_window_size - 1,
                               0x1000);
+        }
     } else {
         error_report("vfio: No available IOMMU models");
         ret = -EINVAL;

hw/vfio/spapr.c

@@ -137,3 +137,74 @@ const MemoryListener vfio_prereg_listener = {
     .region_add = vfio_prereg_listener_region_add,
     .region_del = vfio_prereg_listener_region_del,
 };
+
+int vfio_spapr_create_window(VFIOContainer *container,
+                             MemoryRegionSection *section,
+                             hwaddr *pgsize)
+{
+    int ret;
+    unsigned pagesize = memory_region_iommu_get_min_page_size(section->mr);
+    unsigned entries, pages;
+    struct vfio_iommu_spapr_tce_create create = { .argsz = sizeof(create) };
+
+    /*
+     * FIXME: For VFIO iommu types which have KVM acceleration to
+     * avoid bouncing all map/unmaps through qemu this way, this
+     * would be the right place to wire that up (tell the KVM
+     * device emulation the VFIO iommu handles to use).
+     */
+    create.window_size = int128_get64(section->size);
+    create.page_shift = ctz64(pagesize);
+    /*
+     * SPAPR host supports multilevel TCE tables, there is some
+     * heuristic to decide how many levels we want for our table:
+     * 0..64 = 1; 65..4096 = 2; 4097..262144 = 3; 262145.. = 4
+     */
+    entries = create.window_size >> create.page_shift;
+    pages = MAX((entries * sizeof(uint64_t)) / getpagesize(), 1);
+    pages = MAX(pow2ceil(pages) - 1, 1); /* Round up */
+    create.levels = ctz64(pages) / 6 + 1;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_CREATE, &create);
+    if (ret) {
+        error_report("Failed to create a window, ret = %d (%m)", ret);
+        return -errno;
+    }
+
+    if (create.start_addr != section->offset_within_address_space) {
+        vfio_spapr_remove_window(container, create.start_addr);
+
+        error_report("Host doesn't support DMA window at %"HWADDR_PRIx", must be %"PRIx64,
+                     section->offset_within_address_space,
+                     (uint64_t)create.start_addr);
+        ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
+        return -EINVAL;
+    }
+    trace_vfio_spapr_create_window(create.page_shift,
+                                   create.window_size,
+                                   create.start_addr);
+    *pgsize = pagesize;
+
+    return 0;
+}
+
+int vfio_spapr_remove_window(VFIOContainer *container,
+                             hwaddr offset_within_address_space)
+{
+    struct vfio_iommu_spapr_tce_remove remove = {
+        .argsz = sizeof(remove),
+        .start_addr = offset_within_address_space,
+    };
+    int ret;
+
+    ret = ioctl(container->fd, VFIO_IOMMU_SPAPR_TCE_REMOVE, &remove);
+    if (ret) {
+        error_report("Failed to remove window at %"PRIx64,
+                     (uint64_t)remove.start_addr);
+        return -errno;
+    }
+
+    trace_vfio_spapr_remove_window(offset_within_address_space);
+
+    return 0;
+}

hw/vfio/trace-events

@@ -121,3 +121,5 @@ vfio_prereg_listener_region_add_skip(uint64_t start, uint64_t end) "%"PRIx64" -
 vfio_prereg_listener_region_del_skip(uint64_t start, uint64_t end) "%"PRIx64" - %"PRIx64
 vfio_prereg_register(uint64_t va, uint64_t size, int ret) "va=%"PRIx64" size=%"PRIx64" ret=%d"
 vfio_prereg_unregister(uint64_t va, uint64_t size, int ret) "va=%"PRIx64" size=%"PRIx64" ret=%d"
+vfio_spapr_create_window(int ps, uint64_t ws, uint64_t off) "pageshift=0x%x winsize=0x%"PRIx64" offset=0x%"PRIx64
+vfio_spapr_remove_window(uint64_t off) "offset=%"PRIx64

include/hw/vfio/vfio-common.h

@@ -168,4 +168,10 @@ int vfio_get_dev_region_info(VFIODevice *vbasedev, uint32_t type,
 #endif
 extern const MemoryListener vfio_prereg_listener;
 
+int vfio_spapr_create_window(VFIOContainer *container,
+                             MemoryRegionSection *section,
+                             hwaddr *pgsize);
+int vfio_spapr_remove_window(VFIOContainer *container,
+                             hwaddr offset_within_address_space);
+
 #endif /* !HW_VFIO_VFIO_COMMON_H */