[RFC 16/18] vfio/iommufd: Add IOAS_COPY_DMA support

Yi Liu
2022-04-14T10:47:50Z

Compared with legacy vfio container BE, one of the benefits provided by
iommufd is to reduce the redundant page pinning on kernel side through
the usage of IOAS_COPY_DMA. For iommufd containers within the same address
space, IOVA mappings can be copied from a source container to destination
container.

To achieve this, move the vfio_memory_listener to be per address space.
In the memory listener callbacks, all the containers within the address
space will be looped. For the iommufd containers, QEMU uses IOAS_MAP_DMA
on the first one, and then uses IOAS_COPY_DMA to copy the IOVA mappings
from the first iommufd container to other iommufd containers within the
address space. For legacy containers, IOVA mapping is done by
VFIO_IOMMU_MAP_DMA.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
hw/vfio/as.c | 117 +++++++++++++++++++++++----
hw/vfio/container-obj.c | 17 +++-
hw/vfio/container.c | 19 ++---
hw/vfio/iommufd.c | 43 +++++++---
include/hw/vfio/vfio-common.h | 6 +-
include/hw/vfio/vfio-container-obj.h | 8 +-
6 files changed, 167 insertions(+), 43 deletions(-)

diff --git a/hw/vfio/as.c b/hw/vfio/as.c
index 94618efd1f..13a6653a0d 100644
--- a/hw/vfio/as.c
+++ b/hw/vfio/as.c
@@ -388,16 +388,16 @@ static void vfio_unregister_ram_discard_listener(VFIOContainer *container,
g_free(vrdl);
}

-static void vfio_listener_region_add(MemoryListener *listener,
- MemoryRegionSection *section)
+static void vfio_container_region_add(VFIOContainer *container,
+ VFIOContainer **src_container,
+ MemoryRegionSection *section)
{
- VFIOContainer *container = container_of(listener, VFIOContainer, listener);
hwaddr iova, end;
Int128 llend, llsize;
void *vaddr;
int ret;
VFIOHostDMAWindow *hostwin;
- bool hostwin_found;
+ bool hostwin_found, copy_dma_supported = false;
Error *err = NULL;

if (vfio_listener_skipped_section(section)) {
@@ -533,12 +533,25 @@ static void vfio_listener_region_add(MemoryListener *listener,
}
}

+ copy_dma_supported = vfio_container_check_extension(container,
+ VFIO_FEAT_DMA_COPY);
+
+ if (copy_dma_supported && *src_container) {
+ if (!vfio_container_dma_copy(*src_container, container,
+ iova, int128_get64(llsize),
+ section->readonly)) {
+ return;
+ } else {
+ info_report("IOAS copy failed try map for container: %p", container);
+ }
+ }
+
ret = vfio_container_dma_map(container, iova, int128_get64(llsize),
vaddr, section->readonly);
if (ret) {
- error_setg(&err, "vfio_dma_map(%p, 0x%"HWADDR_PRIx", "
- "0x%"HWADDR_PRIx", %p) = %d (%m)",
- container, iova, int128_get64(llsize), vaddr, ret);
+ error_setg(&err, "vfio_container_dma_map(%p, 0x%"HWADDR_PRIx", "
+ "0x%"HWADDR_PRIx", %p) = %d (%m)", container, iova,
+ int128_get64(llsize), vaddr, ret);
if (memory_region_is_ram_device(section->mr)) {
/* Allow unexpected mappings not to be fatal for RAM devices */
error_report_err(err);
@@ -547,6 +560,9 @@ static void vfio_listener_region_add(MemoryListener *listener,
goto fail;
}

+ if (copy_dma_supported) {
+ *src_container = container;
+ }
return;

fail:
@@ -573,10 +589,22 @@ fail:
}
}

-static void vfio_listener_region_del(MemoryListener *listener,
+static void vfio_listener_region_add(MemoryListener *listener,
MemoryRegionSection *section)
{
- VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+ VFIOAddressSpace *space = container_of(listener,
+ VFIOAddressSpace, listener);
+ VFIOContainer *container, *src_container;
+
+ src_container = NULL;
+ QLIST_FOREACH(container, &space->containers, next) {
+ vfio_container_region_add(container, &src_container, section);
+ }
+}
+
+static void vfio_container_region_del(VFIOContainer *container,
+ MemoryRegionSection *section)
+{
hwaddr iova, end;
Int128 llend, llsize;
int ret;
@@ -682,18 +710,38 @@ static void vfio_listener_region_del(MemoryListener *listener,
vfio_container_del_section_window(container, section);
}

+static void vfio_listener_region_del(MemoryListener *listener,
+ MemoryRegionSection *section)
+{
+ VFIOAddressSpace *space = container_of(listener,
+ VFIOAddressSpace, listener);
+ VFIOContainer *container;
+
+ QLIST_FOREACH(container, &space->containers, next) {
+ vfio_container_region_del(container, section);
+ }
+}
+
static void vfio_listener_log_global_start(MemoryListener *listener)
{
- VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+ VFIOAddressSpace *space = container_of(listener,
+ VFIOAddressSpace, listener);
+ VFIOContainer *container;

- vfio_container_set_dirty_page_tracking(container, true);
+ QLIST_FOREACH(container, &space->containers, next) {
+ vfio_container_set_dirty_page_tracking(container, true);
+ }
}

static void vfio_listener_log_global_stop(MemoryListener *listener)
{
- VFIOContainer *container = container_of(listener, VFIOContainer, listener);
+ VFIOAddressSpace *space = container_of(listener,
+ VFIOAddressSpace, listener);
+ VFIOContainer *container;

- vfio_container_set_dirty_page_tracking(container, false);
+ QLIST_FOREACH(container, &space->containers, next) {
+ vfio_container_set_dirty_page_tracking(container, false);
+ }
}

typedef struct {
@@ -823,11 +871,9 @@ static int vfio_sync_dirty_bitmap(VFIOContainer *container,
int128_get64(section->size), ram_addr);
}

-static void vfio_listener_log_sync(MemoryListener *listener,
- MemoryRegionSection *section)
+static void vfio_container_log_sync(VFIOContainer *container,
+ MemoryRegionSection *section)
{
- VFIOContainer *container = container_of(listener, VFIOContainer, listener);
-
if (vfio_listener_skipped_section(section) ||
!container->dirty_pages_supported) {
return;
@@ -838,6 +884,18 @@ static void vfio_listener_log_sync(MemoryListener *listener,
}
}

+static void vfio_listener_log_sync(MemoryListener *listener,
+ MemoryRegionSection *section)
+{
+ VFIOAddressSpace *space = container_of(listener,
+ VFIOAddressSpace, listener);
+ VFIOContainer *container;
+
+ QLIST_FOREACH(container, &space->containers, next) {
+ vfio_container_log_sync(container, section);
+ }
+}
+
const MemoryListener vfio_memory_listener = {
.name = "vfio",
.region_add = vfio_listener_region_add,
@@ -882,6 +940,31 @@ VFIOAddressSpace *vfio_get_address_space(AddressSpace *as)
return space;
}

+void vfio_as_add_container(VFIOAddressSpace *space,
+ VFIOContainer *container)
+{
+ if (space->listener_initialized) {
+ memory_listener_unregister(&space->listener);
+ }
+
+ QLIST_INSERT_HEAD(&space->containers, container, next);
+
+ /* Unregistration happen in vfio_as_del_container() */
+ space->listener = vfio_memory_listener;
+ memory_listener_register(&space->listener, space->as);
+ space->listener_initialized = true;
+}
+
+void vfio_as_del_container(VFIOAddressSpace *space,
+ VFIOContainer *container)
+{
+ QLIST_SAFE_REMOVE(container, next);
+
+ if (QLIST_EMPTY(&space->containers)) {
+ memory_listener_unregister(&space->listener);
+ }
+}
+
void vfio_put_address_space(VFIOAddressSpace *space)
{
if (QLIST_EMPTY(&space->containers)) {
diff --git a/hw/vfio/container-obj.c b/hw/vfio/container-obj.c
index c4220336af..2c79089364 100644
--- a/hw/vfio/container-obj.c
+++ b/hw/vfio/container-obj.c
@@ -27,6 +27,7 @@
#include "qom/object.h"
#include "qapi/visitor.h"
#include "hw/vfio/vfio-container-obj.h"
+#include "exec/memory.h"

bool vfio_container_check_extension(VFIOContainer *container,
VFIOContainerFeature feat)
@@ -53,6 +54,20 @@ int vfio_container_dma_map(VFIOContainer *container,
return vccs->dma_map(container, iova, size, vaddr, readonly);
}

+int vfio_container_dma_copy(VFIOContainer *src, VFIOContainer *dst,
+ hwaddr iova, ram_addr_t size, bool readonly)
+{
+ VFIOContainerClass *vccs1 = VFIO_CONTAINER_OBJ_GET_CLASS(src);
+ VFIOContainerClass *vccs2 = VFIO_CONTAINER_OBJ_GET_CLASS(dst);
+
+ if (!vccs1->dma_copy || vccs1->dma_copy != vccs2->dma_copy) {
+ error_report("Incompatiable container: unable to copy dma");
+ return -EINVAL;
+ }
+
+ return vccs1->dma_copy(src, dst, iova, size, readonly);
+}
+
int vfio_container_dma_unmap(VFIOContainer *container,
hwaddr iova, ram_addr_t size,
IOMMUTLBEntry *iotlb)
@@ -165,8 +180,6 @@ void vfio_container_destroy(VFIOContainer *container)
VFIOGuestIOMMU *giommu, *tmp;
VFIOHostDMAWindow *hostwin, *next;

- QLIST_SAFE_REMOVE(container, next);
-
QLIST_FOREACH_SAFE(vrdl, &container->vrdl_list, next, vrdl_tmp) {
RamDiscardManager *rdm;

diff --git a/hw/vfio/container.c b/hw/vfio/container.c
index 2f59422048..6bc1b8763f 100644
--- a/hw/vfio/container.c
+++ b/hw/vfio/container.c
@@ -357,9 +357,6 @@ err_out:

static void vfio_listener_release(VFIOLegacyContainer *container)
{
- VFIOContainer *bcontainer = &container->obj;
-
- memory_listener_unregister(&bcontainer->listener);
if (container->iommu_type == VFIO_SPAPR_TCE_v2_IOMMU) {
memory_listener_unregister(&container->prereg_listener);
}
@@ -887,14 +884,11 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
vfio_kvm_device_add_group(group);

QLIST_INIT(&container->group_list);
- QLIST_INSERT_HEAD(&space->containers, bcontainer, next);

group->container = container;
QLIST_INSERT_HEAD(&container->group_list, group, container_next);

- bcontainer->listener = vfio_memory_listener;
-
- memory_listener_register(&bcontainer->listener, bcontainer->space->as);
+ vfio_as_add_container(space, bcontainer);

if (bcontainer->error) {
ret = -1;
@@ -907,8 +901,8 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,

return 0;
listener_release_exit:
+ vfio_as_del_container(space, bcontainer);
QLIST_REMOVE(group, container_next);
- QLIST_REMOVE(bcontainer, next);
vfio_kvm_device_del_group(group);
vfio_listener_release(container);

@@ -931,6 +925,7 @@ static void vfio_disconnect_container(VFIOGroup *group)
{
VFIOLegacyContainer *container = group->container;
VFIOContainer *bcontainer = &container->obj;
+ VFIOAddressSpace *space = bcontainer->space;

QLIST_REMOVE(group, container_next);
group->container = NULL;
@@ -938,10 +933,12 @@ static void vfio_disconnect_container(VFIOGroup *group)
/*
* Explicitly release the listener first before unset container,
* since unset may destroy the backend container if it's the last
- * group.
+ * group. By removing container from the list, container is disconnected
+ * with address space memory listener.
*/
if (QLIST_EMPTY(&container->group_list)) {
vfio_listener_release(container);
+ vfio_as_del_container(space, bcontainer);
}

if (ioctl(group->fd, VFIO_GROUP_UNSET_CONTAINER, &container->fd)) {
@@ -950,10 +947,8 @@ static void vfio_disconnect_container(VFIOGroup *group)
}

if (QLIST_EMPTY(&container->group_list)) {
- VFIOAddressSpace *space = bcontainer->space;
-
- vfio_container_destroy(bcontainer);
trace_vfio_disconnect_container(container->fd);
+ vfio_container_destroy(bcontainer);
close(container->fd);
g_free(container);

diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
index f8375f1672..8ff5988b07 100644
--- a/hw/vfio/iommufd.c
+++ b/hw/vfio/iommufd.c
@@ -38,6 +38,8 @@ static bool iommufd_check_extension(VFIOContainer *bcontainer,
VFIOContainerFeature feat)
{
switch (feat) {
+ case VFIO_FEAT_DMA_COPY:
+ return true;
default:
return false;
};
@@ -49,10 +51,25 @@ static int iommufd_map(VFIOContainer *bcontainer, hwaddr iova,
VFIOIOMMUFDContainer *container = container_of(bcontainer,
VFIOIOMMUFDContainer, obj);

- return iommufd_map_dma(container->iommufd, container->ioas_id,
+ return iommufd_map_dma(container->iommufd,
+ container->ioas_id,
iova, size, vaddr, readonly);
}

+static int iommufd_copy(VFIOContainer *src, VFIOContainer *dst,
+ hwaddr iova, ram_addr_t size, bool readonly)
+{
+ VFIOIOMMUFDContainer *container_src = container_of(src,
+ VFIOIOMMUFDContainer, obj);
+ VFIOIOMMUFDContainer *container_dst = container_of(dst,
+ VFIOIOMMUFDContainer, obj);
+
+ assert(container_src->iommufd == container_dst->iommufd);
+
+ return iommufd_copy_dma(container_src->iommufd, container_src->ioas_id,
+ container_dst->ioas_id, iova, size, readonly);
+}
+
static int iommufd_unmap(VFIOContainer *bcontainer,
hwaddr iova, ram_addr_t size,
IOMMUTLBEntry *iotlb)
@@ -428,12 +445,7 @@ static int iommufd_attach_device(VFIODevice *vbasedev, AddressSpace *as,
* between iommufd and kvm.
*/

- QLIST_INSERT_HEAD(&space->containers, bcontainer, next);
-
- bcontainer->listener = vfio_memory_listener;
-
- memory_listener_register(&bcontainer->listener, bcontainer->space->as);
-
+ vfio_as_add_container(space, bcontainer);
bcontainer->initialized = true;

out:
@@ -476,6 +488,7 @@ static void iommufd_detach_device(VFIODevice *vbasedev)
VFIOIOMMUFDContainer *container;
VFIODevice *vbasedev_iter;
VFIOIOASHwpt *hwpt;
+ VFIOAddressSpace *space;
Error *err;

if (!bcontainer) {
@@ -501,15 +514,26 @@ found:
vfio_container_put_hwpt(hwpt);
}

+ space = bcontainer->space;
+ /*
+ * Needs to remove the bcontainer from space->containers list before
+ * detach container. Otherwise, detach container may destroy the
+ * container if it's the last device. By removing bcontainer from the
+ * list, container is disconnected with address space memory listener.
+ */
+ if (QLIST_EMPTY(&container->hwpt_list)) {
+ vfio_as_del_container(space, bcontainer);
+ }
__vfio_device_detach_container(vbasedev, container, &err);
if (err) {
error_report_err(err);
}
if (QLIST_EMPTY(&container->hwpt_list)) {
- VFIOAddressSpace *space = bcontainer->space;
+ int iommufd = container->iommufd;
+ uint32_t ioas_id = container->ioas_id;

- iommufd_put_ioas(container->iommufd, container->ioas_id);
vfio_iommufd_container_destroy(container);
+ iommufd_put_ioas(iommufd, ioas_id);
vfio_put_address_space(space);
}
vbasedev->container = NULL;
@@ -525,6 +549,7 @@ static void vfio_iommufd_class_init(ObjectClass *klass,

vccs->check_extension = iommufd_check_extension;
vccs->dma_map = iommufd_map;
+ vccs->dma_copy = iommufd_copy;
vccs->dma_unmap = iommufd_unmap;
vccs->attach_device = iommufd_attach_device;
vccs->detach_device = iommufd_detach_device;
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 19731ea685..bef48ddfaf 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -34,8 +34,6 @@

#define VFIO_MSG_PREFIX "vfio %s: "

-extern const MemoryListener vfio_memory_listener;
-
enum {
VFIO_DEVICE_TYPE_PCI = 0,
VFIO_DEVICE_TYPE_PLATFORM = 1,
@@ -181,6 +179,10 @@ void vfio_host_win_add(VFIOContainer *bcontainer,
int vfio_host_win_del(VFIOContainer *bcontainer, hwaddr min_iova,
hwaddr max_iova);
VFIOAddressSpace *vfio_get_address_space(AddressSpace *as);
+void vfio_as_add_container(VFIOAddressSpace *space,
+ VFIOContainer *bcontainer);
+void vfio_as_del_container(VFIOAddressSpace *space,
+ VFIOContainer *container);
void vfio_put_address_space(VFIOAddressSpace *space);

void vfio_put_base_device(VFIODevice *vbasedev);
diff --git a/include/hw/vfio/vfio-container-obj.h b/include/hw/vfio/vfio-container-obj.h
index b5ef2160d8..b65f827bc1 100644
--- a/include/hw/vfio/vfio-container-obj.h
+++ b/include/hw/vfio/vfio-container-obj.h
@@ -47,12 +47,15 @@

typedef enum VFIOContainerFeature {
VFIO_FEAT_LIVE_MIGRATION,
+ VFIO_FEAT_DMA_COPY,
} VFIOContainerFeature;

typedef struct VFIOContainer VFIOContainer;

typedef struct VFIOAddressSpace {
AddressSpace *as;
+ MemoryListener listener;
+ bool listener_initialized;
QLIST_HEAD(, VFIOContainer) containers;
QLIST_ENTRY(VFIOAddressSpace) list;
} VFIOAddressSpace;
@@ -90,7 +93,6 @@ struct VFIOContainer {
Object parent_obj;

VFIOAddressSpace *space;
- MemoryListener listener;
Error *error;
bool initialized;
bool dirty_pages_supported;
@@ -116,6 +118,8 @@ typedef struct VFIOContainerClass {
int (*dma_map)(VFIOContainer *container,
hwaddr iova, ram_addr_t size,
void *vaddr, bool readonly);
+ int (*dma_copy)(VFIOContainer *src, VFIOContainer *dst,
+ hwaddr iova, ram_addr_t size, bool readonly);
int (*dma_unmap)(VFIOContainer *container,
hwaddr iova, ram_addr_t size,
IOMMUTLBEntry *iotlb);
@@ -141,6 +145,8 @@ bool vfio_container_check_extension(VFIOContainer *container,
int vfio_container_dma_map(VFIOContainer *container,
hwaddr iova, ram_addr_t size,
void *vaddr, bool readonly);
+int vfio_container_dma_copy(VFIOContainer *src, VFIOContainer *dst,
+ hwaddr iova, ram_addr_t size, bool readonly);
int vfio_container_dma_unmap(VFIOContainer *container,
hwaddr iova, ram_addr_t size,
IOMMUTLBEntry *iotlb);
--
2.27.0