Re: [PATCH v17 Kernel 6/7] vfio iommu: Adds flag to indicate dirty pages tracking capability support

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





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?

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.

Thanks,
Kirti



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux