[Qemu-devel] [PATCH qemu v17 10/12] vfio/spapr: Create DMA window dynamically (SPAPR IOMMU v2)

[Alexey Kardashevskiy <aik@ozlabs.ru>]

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 VFIO_IOMMU_SPAPR_TCE_CREATE ioctl to vfio_listener_region_add
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>
---
Changes:
v17:
* moved spapr window create/remove helpers to separate file
* added hw_error() if vfio_host_win_del() failed

v16:
* used memory_region_iommu_get_page_sizes() in vfio_listener_region_add()
* enforced no intersections between windows

v14:
* new to the series
---
 hw/vfio/common.c              | 76 +++++++++++++++++++++++++++++++++++++------
 hw/vfio/spapr.c               | 70 +++++++++++++++++++++++++++++++++++++++
 include/hw/vfio/vfio-common.h |  6 ++++
 trace-events                  |  2 ++
 4 files changed, 144 insertions(+), 10 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 52b08fd..7f55c26 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -275,6 +275,18 @@ 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)
+{
+    VFIOHostDMAWindow *hostwin = vfio_host_win_lookup(container, min_iova, 1);
+
+    if (!hostwin) {
+        return -1;
+    }
+    QLIST_REMOVE(hostwin, hostwin_next);
+
+    return 0;
+}
+
 static bool vfio_listener_skipped_section(MemoryRegionSection *section)
 {
     return (!memory_region_is_ram(section->mr) &&
@@ -388,6 +400,30 @@ 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))) {
+                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);
+    }
+
     if (!vfio_host_win_lookup(container, iova, end)) {
         error_report("vfio: IOMMU container %p can't map guest IOVA region"
                      " 0x%"HWADDR_PRIx"..0x%"HWADDR_PRIx,
@@ -523,6 +559,18 @@ 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) < 0) {
+            hw_error("%s: Cannot delete missing window at %"HWADDR_PRIx,
+                     __func__, section->offset_within_address_space);
+        }
+
+        trace_vfio_spapr_remove_window(section->offset_within_address_space);
+    }
 }
 
 static const MemoryListener vfio_memory_listener = {
@@ -960,11 +1008,6 @@ 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) {
@@ -973,11 +1016,24 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
             goto listener_release_exit;
         }
 
-        /* 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);
+        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;
diff --git a/hw/vfio/spapr.c b/hw/vfio/spapr.c
index f339472..0c784c4 100644
--- a/hw/vfio/spapr.c
+++ b/hw/vfio/spapr.c
@@ -135,3 +135,73 @@ 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 pagesizes = memory_region_iommu_get_page_sizes(section->mr);
+    unsigned pagesize = (hwaddr)1 << ctz64(pagesizes);
+    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,
+                     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,
+                     remove.start_addr);
+        return -errno;
+    }
+
+    return 0;
+}
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index c76ddc4..7e80382 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -167,4 +167,10 @@ 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 */
diff --git a/trace-events b/trace-events
index ddb8676..ec32c20 100644
--- a/trace-events
+++ b/trace-events
@@ -1768,6 +1768,8 @@ vfio_region_sparse_mmap_entry(int i, unsigned long start, unsigned long end) "sp
 vfio_get_dev_region(const char *name, int index, uint32_t type, uint32_t subtype) "%s index %d, %08x/%0x8"
 vfio_ram_register(uint64_t va, uint64_t size, int ret) "va=%"PRIx64" size=%"PRIx64" ret=%d"
 vfio_ram_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
 
 # hw/vfio/platform.c
 vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d"
-- 
2.5.0.rc3