Use the newly introduced SHM_PAGE_SHIFT register to read the page shift
for the shared memory region, derive the page size from it and store the
resulting value into virtio_shm_region.
Signed-off-by: Sergio Lopez <slp@xxxxxxxxxx>
---
drivers/virtio/virtio_mmio.c | 11 ++++++++++-
include/uapi/linux/virtio_mmio.h | 3 +++
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index 1f594b626d7a7734e8ec58766737a118c26bad94..0f892770739ea84b3e7be5615332773049b10ab1 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -537,6 +537,7 @@ static bool vm_get_shm_region(struct virtio_device *vdev,
struct virtio_shm_region *region, u8 id)
{
struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+ u8 page_shift = 0;
u64 len, addr;
/* Select the region we're interested in */
@@ -560,7 +561,15 @@ static bool vm_get_shm_region(struct virtio_device *vdev,
region->addr = addr;
- region->page_size = 4096;
+ /* If supported by the device transport, read the region page size.
+ * The page_shift variable is initialized to zero above, so if this
+ * feature isn't supported it will result in a page_size of 4096, a
+ * default safe value.
+ */
+ if (__virtio_test_bit(vdev, VIRTIO_F_SHM_PAGE_SIZE))
+ page_shift = (u8) readl(vm_dev->base + VIRTIO_MMIO_SHM_PAGE_SHIFT);
+
+ region->page_size = 1 << (page_shift + 12);
return true;
}
diff --git a/include/uapi/linux/virtio_mmio.h b/include/uapi/linux/virtio_mmio.h
index 0650f91bea6c70f935764070d825d181a2379afb..43348be30eff90ee228b6490b9d3c35ba4c50aa5 100644
--- a/include/uapi/linux/virtio_mmio.h
+++ b/include/uapi/linux/virtio_mmio.h
@@ -133,6 +133,9 @@
#define VIRTIO_MMIO_SHM_BASE_LOW 0x0b8
#define VIRTIO_MMIO_SHM_BASE_HIGH 0x0bc
+/* Shared memory region page shift */
+#define VIRTIO_MMIO_SHM_PAGE_SHIFT 0x0c4
+
/* Configuration atomicity value */
#define VIRTIO_MMIO_CONFIG_GENERATION 0x0fc
--
2.48.1
