[RFC PATCH] vfio: Implement new Ioctl VFIO_IOMMU_GET_DIRTY_BITMAP

From: Yulei Zhang
Date: Tue Apr 10 2018 - 04:12:16 EST


Corresponding to the V4 migration patch set for vfio pci device,
this patch is to implement the new ioctl VFIO_IOMMU_GET_DIRTY_BITMAP
to fulfill the requirement for vfio-mdev device live migration, which
need copy the memory that has been pinned in iommu container to the
target VM for mdev device status restore.

Signed-off-by: Yulei Zhang <yulei.zhang@xxxxxxxxx>
---
drivers/vfio/vfio_iommu_type1.c | 42 +++++++++++++++++++++++++++++++++++++++++
include/uapi/linux/vfio.h | 14 ++++++++++++++
2 files changed, 56 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 5c212bf..6cd2142 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -41,6 +41,7 @@
#include <linux/notifier.h>
#include <linux/dma-iommu.h>
#include <linux/irqdomain.h>
+#include <linux/vmalloc.h>

#define DRIVER_VERSION "0.2"
#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@xxxxxxxxxx>"
@@ -1658,6 +1659,23 @@ static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
return ret;
}

+static void vfio_dma_update_dirty_bitmap(struct vfio_iommu *iommu,
+ u64 start_addr, u64 npage, void *bitmap)
+{
+ u64 iova = start_addr;
+ struct vfio_dma *dma;
+ int i;
+
+ for (i = 0; i < npage; i++) {
+ dma = vfio_find_dma(iommu, iova, PAGE_SIZE);
+ if (dma)
+ if (vfio_find_vpfn(dma, iova))
+ set_bit(i, bitmap);
+
+ iova += PAGE_SIZE;
+ }
+}
+
static long vfio_iommu_type1_ioctl(void *iommu_data,
unsigned int cmd, unsigned long arg)
{
@@ -1728,6 +1746,30 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,

return copy_to_user((void __user *)arg, &unmap, minsz) ?
-EFAULT : 0;
+ } else if (cmd == VFIO_IOMMU_GET_DIRTY_BITMAP) {
+ struct vfio_iommu_get_dirty_bitmap d;
+ unsigned long bitmap_sz;
+ unsigned int *bitmap;
+
+ minsz = offsetofend(struct vfio_iommu_get_dirty_bitmap,
+ page_nr);
+
+ if (copy_from_user(&d, (void __user *)arg, minsz))
+ return -EFAULT;
+
+ bitmap_sz = (BITS_TO_LONGS(d.page_nr) + 1) *
+ sizeof(unsigned long);
+ bitmap = vzalloc(bitmap_sz);
+ vfio_dma_update_dirty_bitmap(iommu, d.start_addr,
+ d.page_nr, bitmap);
+
+ if (copy_to_user((void __user *)arg + minsz,
+ bitmap, bitmap_sz)) {
+ vfree(bitmap);
+ return -EFAULT;
+ }
+ vfree(bitmap);
+ return 0;
}

return -ENOTTY;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 1aa7b82..d4fd5af 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -665,6 +665,20 @@ 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 - _IOW(VFIO_TYPE, VFIO_BASE + 17,
+ * struct vfio_iommu_get_dirty_bitmap)
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_iommu_get_dirty_bitmap {
+ __u64 start_addr;
+ __u64 page_nr;
+ __u8 dirty_bitmap[];
+};
+
+#define VFIO_IOMMU_GET_DIRTY_BITMAP _IO(VFIO_TYPE, VFIO_BASE + 17)
+
/* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */

/*
--
2.7.4