[PATCH v6 1/8] vfio: Enable sparse mmap capability

Alex Williamson
2016-05-17T20:19:26Z

The sparse mmap capability in a vfio region info allows vfio to tell
us which sub-areas of a region may be mmap'd. Thus rather than
assuming a single mmap covers the entire region and later frobbing it
ourselves for things like the PCI MSI-X vector table, we can read that
directly from vfio.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
hw/vfio/common.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++---
trace-events | 2 ++
2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index f27db36..eb6f04e 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -496,6 +496,54 @@ static void vfio_listener_release(VFIOContainer *container)
memory_listener_unregister(&container->listener);
}

+static struct vfio_info_cap_header *
+vfio_get_region_info_cap(struct vfio_region_info *info, uint16_t id)
+{
+ struct vfio_info_cap_header *hdr;
+ void *ptr = info;
+
+ if (!(info->flags & VFIO_REGION_INFO_FLAG_CAPS)) {
+ return NULL;
+ }
+
+ for (hdr = ptr + info->cap_offset; hdr != ptr; hdr = ptr + hdr->next) {
+ if (hdr->id == id) {
+ return hdr;
+ }
+ }
+
+ return NULL;
+}
+
+static void vfio_setup_region_sparse_mmaps(VFIORegion *region,
+ struct vfio_region_info *info)
+{
+ struct vfio_info_cap_header *hdr;
+ struct vfio_region_info_cap_sparse_mmap *sparse;
+ int i;
+
+ hdr = vfio_get_region_info_cap(info, VFIO_REGION_INFO_CAP_SPARSE_MMAP);
+ if (!hdr) {
+ return;
+ }
+
+ sparse = container_of(hdr, struct vfio_region_info_cap_sparse_mmap, header);
+
+ trace_vfio_region_sparse_mmap_header(region->vbasedev->name,
+ region->nr, sparse->nr_areas);
+
+ region->nr_mmaps = sparse->nr_areas;
+ region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
+
+ for (i = 0; i < region->nr_mmaps; i++) {
+ region->mmaps[i].offset = sparse->areas[i].offset;
+ region->mmaps[i].size = sparse->areas[i].size;
+ trace_vfio_region_sparse_mmap_entry(i, region->mmaps[i].offset,
+ region->mmaps[i].offset +
+ region->mmaps[i].size);
+ }
+}
+
int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
int index, const char *name)
{
@@ -522,11 +570,14 @@ int vfio_region_setup(Object *obj, VFIODevice *vbasedev, VFIORegion *region,
region->flags & VFIO_REGION_INFO_FLAG_MMAP &&
!(region->size & ~qemu_real_host_page_mask)) {

- region->nr_mmaps = 1;
- region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
+ vfio_setup_region_sparse_mmaps(region, info);

- region->mmaps[0].offset = 0;
- region->mmaps[0].size = region->size;
+ if (!region->nr_mmaps) {
+ region->nr_mmaps = 1;
+ region->mmaps = g_new0(VFIOMmap, region->nr_mmaps);
+ region->mmaps[0].offset = 0;
+ region->mmaps[0].size = region->size;
+ }
}
}

@@ -1086,6 +1137,7 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
*info = g_malloc0(argsz);

(*info)->index = index;
+retry:
(*info)->argsz = argsz;

if (ioctl(vbasedev->fd, VFIO_DEVICE_GET_REGION_INFO, *info)) {
@@ -1093,6 +1145,13 @@ int vfio_get_region_info(VFIODevice *vbasedev, int index,
return -errno;
}

+ if ((*info)->argsz > argsz) {
+ argsz = (*info)->argsz;
+ *info = g_realloc(*info, argsz);
+
+ goto retry;
+ }
+
return 0;
}

diff --git a/trace-events b/trace-events
index 4fce005..99c5132 100644
--- a/trace-events
+++ b/trace-events
@@ -1734,6 +1734,8 @@ vfio_region_mmap(const char *name, unsigned long offset, unsigned long end) "Reg
vfio_region_exit(const char *name, int index) "Device %s, region %d"
vfio_region_finalize(const char *name, int index) "Device %s, region %d"
vfio_region_mmaps_set_enabled(const char *name, bool enabled) "Region %s mmaps enabled: %d"
+vfio_region_sparse_mmap_header(const char *name, int index, int nr_areas) "Device %s region %d: %d sparse mmap entries"
+vfio_region_sparse_mmap_entry(int i, off_t start, off_t end) "sparse entry %d [0x%lx - 0x%lx]"

# hw/vfio/platform.c
vfio_platform_base_device_init(char *name, int groupid) "%s belongs to group #%d"