[Qemu-devel] [PATCH v4 08/18] vfio: Add DMA memory registering

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This makes use of the new "memory registering" feature. The idea is
to provide the guest ability to notify the host kernel about pages which
are going to be used for DMA. Having this information, the host kernel
can pin them all, do locked pages accounting and not spent time on
doing that in real time with possible failures which cannot be handled
nicely in some cases.

This adds a memory listener which notifies a VFIO container about memory
which needs to be pinned/unpinned. VFIO MMIO regions are skipped.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 hw/vfio/common.c              | 99 ++++++++++++++++++++++++++++++++++++++++++-
 include/hw/vfio/vfio-common.h |  3 +-
 2 files changed, 100 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index cf483ff..c08f9ab 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -485,6 +485,99 @@ void vfio_listener_release(VFIOContainer *container)
     memory_listener_unregister(&container->iommu_data.type1.listener);
 }
 
+static int vfio_mem_register(VFIOContainer *container,
+                             void *vaddr, ram_addr_t size)
+{
+    struct vfio_iommu_type1_register_memory reg = {
+        .argsz = sizeof(reg),
+        .vaddr = (__u64)(uintptr_t)vaddr,
+        .size = size,
+    };
+    long ret = ioctl(container->fd, VFIO_IOMMU_REGISTER_MEMORY, &reg);
+
+    DPRINTF("(%u) %s %u: va=%lx size=%lx, ret=%ld\n", getpid(),
+            __func__, __LINE__, reg.vaddr, reg.size, ret);
+
+    return ret;
+}
+
+static int vfio_mem_unregister(VFIOContainer *container,
+                               void *vaddr, ram_addr_t size)
+{
+    struct vfio_iommu_type1_unregister_memory reg = {
+        .argsz = sizeof(reg),
+        .vaddr = (__u64)(uintptr_t)vaddr,
+        .size = size,
+    };
+    long ret = ioctl(container->fd, VFIO_IOMMU_UNREGISTER_MEMORY, &reg);
+
+    DPRINTF("(%u) %s %u: va=%lx size=%lx, ret=%ld\n", getpid(),
+            __func__, __LINE__, reg.vaddr, reg.size, ret);
+
+    return ret;
+}
+
+static void vfio_ram_region_add(MemoryListener *listener,
+                                MemoryRegionSection *section)
+{
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            iommu_data.type1.ramlistener);
+    hwaddr end;
+    Int128 llend;
+    void *vaddr;
+
+    if (!memory_region_is_ram(section->mr) ||
+        memory_region_is_skip_dump(section->mr)) {
+        return;
+    }
+
+    llend = int128_make64(section->offset_within_address_space);
+    llend = int128_add(llend, section->size);
+    llend = int128_and(llend, int128_exts64(TARGET_PAGE_MASK));
+
+    memory_region_ref(section->mr);
+
+    end = int128_get64(llend);
+    vaddr = memory_region_get_ram_ptr(section->mr) +
+        section->offset_within_region;
+    vfio_mem_register(container, vaddr, end);
+}
+
+static void vfio_ram_region_del(MemoryListener *listener,
+                                MemoryRegionSection *section)
+{
+    VFIOContainer *container = container_of(listener, VFIOContainer,
+                                            iommu_data.type1.ramlistener);
+    hwaddr iova, end;
+    void *vaddr;
+
+    if (!memory_region_is_ram(section->mr) ||
+        memory_region_is_skip_dump(section->mr)) {
+        return;
+    }
+
+
+    iova = TARGET_PAGE_ALIGN(section->offset_within_address_space);
+    end = (section->offset_within_address_space + int128_get64(section->size)) &
+        TARGET_PAGE_MASK;
+    vaddr = memory_region_get_ram_ptr(section->mr) +
+        section->offset_within_region +
+        (iova - section->offset_within_address_space);
+
+    vfio_mem_unregister(container, vaddr, end - iova);
+}
+
+const MemoryListener vfio_ram_listener = {
+    .region_add = vfio_ram_region_add,
+    .region_del = vfio_ram_region_del,
+};
+
+static void vfio_spapr_listener_release(VFIOContainer *container)
+{
+    memory_listener_unregister(&container->iommu_data.type1.listener);
+    memory_listener_unregister(&container->iommu_data.type1.ramlistener);
+}
+
 int vfio_mmap_region(Object *obj, VFIORegion *region,
                      MemoryRegion *mem, MemoryRegion *submem,
                      void **map, size_t size, off_t offset,
@@ -705,6 +798,10 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
             goto free_container_exit;
         }
 
+        container->iommu_data.type1.ramlistener = vfio_ram_listener;
+        memory_listener_register(&container->iommu_data.type1.ramlistener,
+                                 &address_space_memory);
+
         /*
          * The host kernel code implementing VFIO_IOMMU_DISABLE is called
          * when container fd is closed so we do not call it explicitly
@@ -718,7 +815,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
         }
 
         container->iommu_data.type1.listener = vfio_memory_listener;
-        container->iommu_data.release = vfio_listener_release;
+        container->iommu_data.release = vfio_spapr_listener_release;
 
         memory_listener_register(&container->iommu_data.type1.listener,
                                  container->space->as);
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 1d5bfe8..3f91216 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -66,6 +66,7 @@ struct VFIOGroup;
 
 typedef struct VFIOType1 {
     MemoryListener listener;
+    MemoryListener ramlistener;
     int error;
     bool initialized;
 } VFIOType1;
@@ -144,7 +145,7 @@ int vfio_get_device(VFIOGroup *group, const char *name,
                     VFIODevice *vbasedev);
 
 extern const MemoryRegionOps vfio_region_ops;
-extern const MemoryListener vfio_memory_listener;
+extern const MemoryListener vfio_memory_listener, vfio_ram_listener;
 extern QLIST_HEAD(vfio_group_head, VFIOGroup) vfio_group_list;
 extern QLIST_HEAD(vfio_as_head, VFIOAddressSpace) vfio_address_spaces;
 
-- 
2.0.0