[PATCH RFC] vfio: Implement new Ioctl VFIO_IOMMU_GET_DIRTY_BITMAP

[Yulei Zhang]

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.zh...@intel.com>
---
 drivers/vfio/vfio_iommu_type1.c | 38 ++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       | 14 ++++++++++++++
 2 files changed, 52 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 8549cb1..fab9e26 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.william...@redhat.com>"
@@ -1526,6 +1527,23 @@ 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)
 {
@@ -1596,6 +1614,26 @@ 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 *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 8424afb..ecf5c53 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -571,6 +571,20 @@ 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