On 11/13/2019 4:00 AM, Alex Williamson wrote:
On Tue, 12 Nov 2019 22:33:37 +0530
Kirti Wankhede <kwankhede@xxxxxxxxxx> wrote:
All pages pinned by vendor driver through vfio_pin_pages API should be
considered as dirty during migration. IOMMU container maintains a list of
all such pinned pages. Added an ioctl defination to get bitmap of such
definition
pinned pages for requested IO virtual address range.
Additionally, all mapped pages are considered dirty when physically
mapped through to an IOMMU, modulo we discussed devices opting in to
per page pinning to indicate finer granularity with a TBD mechanism to
figure out if any non-opt-in devices remain.
You mean, in case of device direct assignment (device pass through)?
Signed-off-by: Kirti Wankhede <kwankhede@xxxxxxxxxx>
Reviewed-by: Neo Jia <cjia@xxxxxxxxxx>
---
include/uapi/linux/vfio.h | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 35b09427ad9f..6fd3822aa610 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -902,6 +902,29 @@ struct vfio_iommu_type1_dma_unmap {
#define VFIO_IOMMU_ENABLE _IO(VFIO_TYPE, VFIO_BASE + 15)
#define VFIO_IOMMU_DISABLE _IO(VFIO_TYPE, VFIO_BASE + 16)
+/**
+ * VFIO_IOMMU_GET_DIRTY_BITMAP - _IOWR(VFIO_TYPE, VFIO_BASE + 17,
+ * struct vfio_iommu_type1_dirty_bitmap)
+ *
+ * IOCTL to get dirty pages bitmap for IOMMU container during migration.
+ * Get dirty pages bitmap of given IO virtual addresses range using
+ * struct vfio_iommu_type1_dirty_bitmap. Caller sets argsz, which is size of
+ * struct vfio_iommu_type1_dirty_bitmap. User should allocate memory to get
+ * bitmap and should set size of allocated memory in bitmap_size field.
+ * One bit is used to represent per page consecutively starting from iova
+ * offset. Bit set indicates page at that offset from iova is dirty.
+ */
+struct vfio_iommu_type1_dirty_bitmap {
+ __u32 argsz;
+ __u32 flags;
+ __u64 iova; /* IO virtual address */
+ __u64 size; /* Size of iova range */
+ __u64 bitmap_size; /* in bytes */
This seems redundant. We can calculate the size of the bitmap based on
the iova size.
But in kernel space, we need to validate the size of memory allocated by
user instead of assuming user is always correct, right?
+ void __user *bitmap; /* one bit per page */
Should we define that as a __u64* to (a) help with the size
calculation, and (b) assure that we can use 8-byte ops on it?
However, who defines page size? Is it necessarily the processor page
size? A physical IOMMU may support page sizes other than the CPU page
size. It might be more important to indicate the expected page size
than the bitmap size. Thanks,
I see in QEMU and in vfio_iommu_type1 module, page sizes considered for
mapping are CPU page size, 4K. Do we still need to have such argument?
Thanks,
Kirti
Alex
+};
+
+#define VFIO_IOMMU_GET_DIRTY_BITMAP _IO(VFIO_TYPE, VFIO_BASE + 17)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */
/*
