cfn/computing-offload
Code Issues Proposed changes
79c4324644
computing-offload/generic_vdpa/qemu/vfio-Maintain-DMA-mapping-range-for-the-container.patch
jiangdongxu 79c4324644 add generic_vdpa basecode 
Change-Id: I2d302dda68298877c65c99147f5bf22186a59aac
2024-09-19 17:19:46 +08:00

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6.7 KiB
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From ac1bf3edcd2b807cf81ada500716f13b1394d58e Mon Sep 17 00:00:00 2001
From: Zenghui Yu <yuzenghui@huawei.com>
Date: Sat, 8 May 2021 17:31:04 +0800
Subject: [PATCH] vfio: Maintain DMA mapping range for the container
When synchronizing dirty bitmap from kernel VFIO we do it in a
per-iova-range fashion and we allocate the userspace bitmap for each of the
ioctl. This patch introduces `struct VFIODMARange` to describe a range of
the given DMA mapping with respect to a VFIO_IOMMU_MAP_DMA operation, and
make the bitmap cache of this range be persistent so that we don't need to
g_try_malloc0() every time. Note that the new structure is almost a copy of
`struct vfio_iommu_type1_dma_map` but only internally used by QEMU.
More importantly, the cached per-iova-range dirty bitmap will be further
used when we want to add support for the CLEAR_BITMAP and this cached
bitmap will be used to guarantee we don't clear any unknown dirty bits
otherwise that can be a severe data loss issue for migration code.
It's pretty intuitive to maintain a bitmap per container since we perform
log_sync at this granule. But I don't know how to deal with things like
memory hot-{un}plug, sparse DMA mappings, etc. Suggestions welcome.
* yet something to-do:
- can't work with guest viommu
- no locks
- etc
[ The idea and even the commit message are largely inherited from kvm side.
See commit 9f4bf4baa8b820c7930e23c9566c9493db7e1d25. ]
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Kunkun Jiang <jinagkunkun@huawei.com>
---
hw/vfio/common.c | 62 +++++++++++++++++++++++++++++++----
include/hw/vfio/vfio-common.h | 9 +++++
2 files changed, 65 insertions(+), 6 deletions(-)
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index 080046e3f5..86ea784919 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -445,6 +445,29 @@ unmap_exit:
return ret;
}
+static VFIODMARange *vfio_lookup_match_range(VFIOContainer *container,
+ hwaddr start_addr, hwaddr size)
+{
+ VFIODMARange *qrange;
+
+ QLIST_FOREACH(qrange, &container->dma_list, next) {
+ if (qrange->iova == start_addr && qrange->size == size) {
+ return qrange;
+ }
+ }
+ return NULL;
+}
+
+static void vfio_dma_range_init_dirty_bitmap(VFIODMARange *qrange)
+{
+ uint64_t pages, size;
+
+ pages = REAL_HOST_PAGE_ALIGN(qrange->size) / qemu_real_host_page_size;
+ size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) / BITS_PER_BYTE;
+
+ qrange->bitmap = g_malloc0(size);
+}
+
/*
* DMA - Mapping and unmapping for the "type1" IOMMU interface used on x86
*/
@@ -458,12 +481,29 @@ static int vfio_dma_unmap(VFIOContainer *container,
.iova = iova,
.size = size,
};
+ VFIODMARange *qrange;
if (iotlb && container->dirty_pages_supported &&
vfio_devices_all_running_and_saving(container)) {
return vfio_dma_unmap_bitmap(container, iova, size, iotlb);
}
+ /*
+ * unregister the DMA range
+ *
+ * It seems that the memory layer will give us the same section as the one
+ * used in region_add(). Otherwise it'll be complicated to manipulate the
+ * bitmap across region_{add,del}. Is there any guarantee?
+ *
+ * But there is really not such a restriction on the kernel interface
+ * (VFIO_IOMMU_DIRTY_PAGES_FLAG_{UN}MAP_DMA, etc).
+ */
+ qrange = vfio_lookup_match_range(container, iova, size);
+ assert(qrange);
+ g_free(qrange->bitmap);
+ QLIST_REMOVE(qrange, next);
+ g_free(qrange);
+
while (ioctl(container->fd, VFIO_IOMMU_UNMAP_DMA, &unmap)) {
/*
* The type1 backend has an off-by-one bug in the kernel (71a7d3d78e3c
@@ -500,6 +540,14 @@ static int vfio_dma_map(VFIOContainer *container, hwaddr iova,
.iova = iova,
.size = size,
};
+ VFIODMARange *qrange;
+
+ qrange = g_malloc0(sizeof(*qrange));
+ qrange->iova = iova;
+ qrange->size = size;
+ QLIST_INSERT_HEAD(&container->dma_list, qrange, next);
+ /* XXX allocate the dirty bitmap on demand */
+ vfio_dma_range_init_dirty_bitmap(qrange);
if (!readonly) {
map.flags |= VFIO_DMA_MAP_FLAG_WRITE;
@@ -1256,9 +1304,14 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
{
struct vfio_iommu_type1_dirty_bitmap *dbitmap;
struct vfio_iommu_type1_dirty_bitmap_get *range;
+ VFIODMARange *qrange;
uint64_t pages;
int ret;
+ qrange = vfio_lookup_match_range(container, iova, size);
+ /* the same as vfio_dma_unmap() */
+ assert(qrange);
+
dbitmap = g_malloc0(sizeof(*dbitmap) + sizeof(*range));
dbitmap->argsz = sizeof(*dbitmap) + sizeof(*range);
@@ -1277,11 +1330,8 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
pages = REAL_HOST_PAGE_ALIGN(range->size) / qemu_real_host_page_size;
range->bitmap.size = ROUND_UP(pages, sizeof(__u64) * BITS_PER_BYTE) /
BITS_PER_BYTE;
- range->bitmap.data = g_try_malloc0(range->bitmap.size);
- if (!range->bitmap.data) {
- ret = -ENOMEM;
- goto err_out;
- }
+
+ range->bitmap.data = (__u64 *)qrange->bitmap;
ret = ioctl(container->fd, VFIO_IOMMU_DIRTY_PAGES, dbitmap);
if (ret) {
@@ -1297,7 +1347,6 @@ static int vfio_get_dirty_bitmap(VFIOContainer *container, uint64_t iova,
trace_vfio_get_dirty_bitmap(container->fd, range->iova, range->size,
range->bitmap.size, ram_addr);
err_out:
- g_free(range->bitmap.data);
g_free(dbitmap);
return ret;
@@ -2061,6 +2110,7 @@ static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
QLIST_INIT(&container->giommu_list);
QLIST_INIT(&container->hostwin_list);
QLIST_INIT(&container->vrdl_list);
+ QLIST_INIT(&container->dma_list);
ret = vfio_init_container(container, group->fd, errp);
if (ret) {
diff --git a/include/hw/vfio/vfio-common.h b/include/hw/vfio/vfio-common.h
index 8af11b0a76..20b9c8a1d3 100644
--- a/include/hw/vfio/vfio-common.h
+++ b/include/hw/vfio/vfio-common.h
@@ -76,6 +76,14 @@ typedef struct VFIOAddressSpace {
struct VFIOGroup;
+typedef struct VFIODMARange {
+ QLIST_ENTRY(VFIODMARange) next;
+ hwaddr iova;
+ size_t size;
+ void *vaddr; /* unused */
+ unsigned long *bitmap; /* dirty bitmap cache for this range */
+} VFIODMARange;
+
typedef struct VFIOContainer {
VFIOAddressSpace *space;
int fd; /* /dev/vfio/vfio, empowered by the attached groups */
@@ -93,6 +101,7 @@ typedef struct VFIOContainer {
QLIST_HEAD(, VFIOHostDMAWindow) hostwin_list;
QLIST_HEAD(, VFIOGroup) group_list;
QLIST_HEAD(, VFIORamDiscardListener) vrdl_list;
+ QLIST_HEAD(, VFIODMARange) dma_list;
QLIST_ENTRY(VFIOContainer) next;
} VFIOContainer;
--
2.27.0
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