[1/3] lib/eal: fix vfio unmap that fails unexpectedly

Message ID 1566392575-7965-2-git-send-email-tallurix.chaitanya.babu@intel.com
State Superseded
Headers show
Series
  • add unit tests for eal vfio library
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Context Check Description
ci/mellanox-Performance-Testing success Performance Testing PASS
ci/intel-Performance-Testing success Performance Testing PASS
ci/iol-Compile-Testing success Compile Testing PASS
ci/Intel-compilation fail Compilation issues
ci/checkpatch success coding style OK

Commit Message

Chaitanya Babu Talluri Aug. 21, 2019, 1:02 p.m.
Unmap of multiple pages fails after a sequence of partial map/unmaps.
The scenario is that multiple maps are created in user_mem_maps,
after multiple map/unmap/remap sequences.

For an example,
Steps:
1. Map 3 pages together
2. Un-map page1
3. Re-map page 1
4. Un-map page 2
5. Re-map page 2
6. Un-map page 3
7. Re-map page 3
8. Un-map all pages

Unmap fails when there are duplicate entries in user_mem_maps.

The fix is to validate if the input VA, IOVA exists in
user_mem_maps before creating map.

Fixes: 73a63908 ("vfio: allow to map other memory regions")
Cc: stable@dpdk.org

Signed-off-by: Chaitanya Babu Talluri <tallurix.chaitanya.babu@intel.com>
---
 lib/librte_eal/linux/eal/eal_vfio.c | 46 +++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

Comments

Burakov, Anatoly Aug. 21, 2019, 1:20 p.m. | #1
On 21-Aug-19 2:02 PM, Chaitanya Babu Talluri wrote:
> Unmap of multiple pages fails after a sequence of partial map/unmaps.
> The scenario is that multiple maps are created in user_mem_maps,
> after multiple map/unmap/remap sequences.
> 
> For an example,
> Steps:
> 1. Map 3 pages together
> 2. Un-map page1
> 3. Re-map page 1
> 4. Un-map page 2
> 5. Re-map page 2
> 6. Un-map page 3
> 7. Re-map page 3
> 8. Un-map all pages

I don't think this description is correct in relation to what is being 
fixed here. The code attempts to prevent overlaps, but there are no 
overlaps in the above example - none of the above operations would 
trigger the added code.

Patch

diff --git a/lib/librte_eal/linux/eal/eal_vfio.c b/lib/librte_eal/linux/eal/eal_vfio.c
index 501c74f23..104912077 100644
--- a/lib/librte_eal/linux/eal/eal_vfio.c
+++ b/lib/librte_eal/linux/eal/eal_vfio.c
@@ -212,6 +212,41 @@  find_user_mem_map(struct user_mem_maps *user_mem_maps, uint64_t addr,
 	return NULL;
 }
 
+static int
+find_user_mem_map_overlap(struct user_mem_maps *user_mem_maps, uint64_t addr,
+		uint64_t iova, uint64_t len)
+{
+	uint64_t va_end = addr + len;
+	uint64_t iova_end = iova + len;
+	int i;
+
+	for (i = 0; i < user_mem_maps->n_maps; i++) {
+		struct user_mem_map *map = &user_mem_maps->maps[i];
+		uint64_t map_va_end = map->addr + map->len;
+		uint64_t map_iova_end = map->iova + map->len;
+
+		bool no_lo_va_overlap = addr < map->addr && va_end <= map->addr;
+		bool no_hi_va_overlap = addr >= map_va_end &&
+			va_end > map_va_end;
+		bool no_lo_iova_overlap = iova < map->iova &&
+			iova_end <= map->iova;
+		bool no_hi_iova_overlap = iova >= map_iova_end &&
+			iova_end > map_iova_end;
+
+		/* check input VA and iova is not within the
+		 * existing map's range
+		 */
+		if ((no_lo_va_overlap || no_hi_va_overlap) &&
+				(no_lo_iova_overlap || no_hi_iova_overlap))
+			continue;
+		else
+			/* map overlaps */
+			return 1;
+	}
+	/* map doesn't overlap */
+	return 0;
+}
+
 /* this will sort all user maps, and merge/compact any adjacent maps */
 static void
 compact_user_maps(struct user_mem_maps *user_mem_maps)
@@ -1732,6 +1767,17 @@  container_dma_map(struct vfio_config *vfio_cfg, uint64_t vaddr, uint64_t iova,
 		ret = -1;
 		goto out;
 	}
+
+	/* check whether vaddr and iova exists in user_mem_maps */
+	ret = find_user_mem_map_overlap(user_mem_maps, vaddr, iova, len);
+	if (ret) {
+		RTE_LOG(ERR, EAL, "Mapping overlaps with a previously "
+				"existing mapping\n");
+		rte_errno = EEXIST;
+		ret = -1;
+		goto out;
+	}
+
 	/* map the entry */
 	if (vfio_dma_mem_map(vfio_cfg, vaddr, iova, len, 1)) {
 		/* technically, this will fail if there are currently no devices