On 4/1/2020 12:45 AM, Alex Williamson wrote:
On Wed, 1 Apr 2020 00:38:49 +0530
Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
On 3/31/2020 2:28 AM, Alex Williamson wrote:
On Mon, 30 Mar 2020 22:20:43 +0530
Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
Flag VFIO_IOMMU_INFO_DIRTY_PGS in VFIO_IOMMU_GET_INFO indicates that driver
support dirty pages tracking.
Signed-off-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Reviewed-by: Neo Jia <cjia@xxxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 3 ++-
include/uapi/linux/vfio.h | 5 +++--
2 files changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 266550bd7307..9fe12b425976 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -2390,7 +2390,8 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
info.cap_offset = 0; /* output, no-recopy necessary */
}
- info.flags = VFIO_IOMMU_INFO_PGSIZES;
+ info.flags = VFIO_IOMMU_INFO_PGSIZES |
+ VFIO_IOMMU_INFO_DIRTY_PGS;
info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index e3cbf8b78623..0fe7c9a6f211 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -985,8 +985,9 @@ struct vfio_device_feature {
struct vfio_iommu_type1_info {
__u32 argsz;
__u32 flags;
-#define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */
-#define VFIO_IOMMU_INFO_CAPS (1 << 1) /* Info supports caps */
+#define VFIO_IOMMU_INFO_PGSIZES (1 << 0) /* supported page sizes info */
+#define VFIO_IOMMU_INFO_CAPS (1 << 1) /* Info supports caps */
+#define VFIO_IOMMU_INFO_DIRTY_PGS (1 << 2) /* supports dirty page tracking */
__u64 iova_pgsizes; /* Bitmap of supported page sizes */
__u32 cap_offset; /* Offset within info struct of first cap */
};
As I just mentioned in my reply to Yan, I'm wondering if
VFIO_CHECK_EXTENSION would be a better way to expose this. The
difference is relatively trivial, but currently the only flag
set by VFIO_IOMMU_GET_INFO is to indicate the presence of a field in
the returned structure. I think this is largely true of other INFO
ioctls within vfio as well and we're already using the
VFIO_CHECK_EXTENSION ioctl to check supported IOMMU models, and IOMMU
cache coherency. We'd simply need to define a VFIO_DIRTY_PGS_IOMMU
value (9) and return 1 for that case. Then when we enable support for
dirt pages that can span multiple mappings, we can add a v2 extensions,
or "MULTI" variant of this extension, since it should be backwards
compatible.
The v2/multi version will again require that the user provide a zero'd
bitmap, but I don't think that should be a problem as part of the
definition of that version (we won't know if the user is using v1 or
v2, but a v1 user should only retrieve bitmaps that exactly match
existing mappings, where all bits will be written). Thanks,
Alex
I look at these two ioctls as : VFIO_CHECK_EXTENSION is used to get
IOMMU type, while VFIO_IOMMU_GET_INFO is used to get properties of a
particular IOMMU type, right?
Not exclusively, see for example VFIO_DMA_CC_IOMMU,
Then I think VFIO_IOMMU_INFO_DIRTY_PGS should be part of
VFIO_IOMMU_GET_INFO and when we add code for v2/multi, a flag should be
added to VFIO_IOMMU_GET_INFO.
Which burns through flags, which is a far more limited resource than
our 32bit extension address space, especially when we're already
planning for one or more extensions to this support. Thanks,
To use flag from VFIO_IOMMU_GET_INFO was your original suggestion, only
3 bits are used here as of now.
Thanks,
Kirti
