Re: [PATCH v2] iommu/amd: Reserve exclusion range in iova-domain

[Jerry Snitselaar]

On Fri Mar 29 19, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@xxxxxxx>
>
> If a device has an exclusion range specified in the IVRS
> table, this region needs to be reserved in the iova-domain
> of that device. This hasn't happened until now and can cause
> data corruption on data transfered with these devices.
>
> Treat exclusion ranges as reserved regions in the iommu-core
> to fix the problem.
>
> Fixes: be2a022c0dd0 ('x86, AMD IOMMU: add functions to parse IOMMU memory mapping requirements for devices')
> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx>

I have a version of this that applies to 4.4 and 4,9 using the older
dm_region code if that would be useful for stable.


--8<--

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 0ad8b7c78a43..f388458624cf 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -3165,11 +3165,14 @@ static void amd_iommu_get_dm_regions(struct device *dev,
		}

		region->start = entry->address_start;
+		region->type = IOMMU_RESV_DIRECT;
		region->length = entry->address_end - entry->address_start;
		if (entry->prot & IOMMU_PROT_IR)
			region->prot |= IOMMU_READ;
		if (entry->prot & IOMMU_PROT_IW)
			region->prot |= IOMMU_WRITE;
+		if (entry->prot & IOMMU_UNITY_MAP_FLAG_EXCL_RANGE)
+			region->type = IOMMU_RESV_RESERVED;

		list_add_tail(&region->list, head);
	}
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 94f1bf772ec9..d84041bc77ac 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1495,6 +1495,9 @@ static int __init init_unity_map_range(struct ivmd_header *m)
	if (e == NULL)
		return -ENOMEM;

+	if (m->flags & IVMD_FLAG_EXCL_RANGE)
+		init_exclusion_range(m);
+
	switch (m->type) {
	default:
		kfree(e);
@@ -1541,9 +1544,7 @@ static int __init init_memory_definitions(struct acpi_table_header *table)

	while (p < end) {
		m = (struct ivmd_header *)p;
-		if (m->flags & IVMD_FLAG_EXCL_RANGE)
-			init_exclusion_range(m);
-		else if (m->flags & IVMD_FLAG_UNITY_MAP)
+		if (m->flags & (IVMD_FLAG_UNITY_MAP | IVMD_FLAG_EXCL_RANGE))
			init_unity_map_range(m);

		p += m->length;
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index b08cf57bf455..31d27eb70565 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -324,6 +324,8 @@
#define IOMMU_PROT_IR 0x01
#define IOMMU_PROT_IW 0x02

+#define IOMMU_UNITY_MAP_FLAG_EXCL_RANGE        (1 << 2)
+
/* IOMMU capabilities */
#define IOMMU_CAP_IOTLB   24
#define IOMMU_CAP_NPCACHE 26
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index a070fa39521a..ef4aa2879952 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -351,6 +351,9 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group,
		start = ALIGN(entry->start, pg_size);
		end   = ALIGN(entry->start + entry->length, pg_size);

+		if (entry->type != IOMMU_RESV_DIRECT)
+			continue;
+
		for (addr = start; addr < end; addr += pg_size) {
			phys_addr_t phys_addr;

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index f28dff313b07..15b7378f67f3 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -115,18 +115,23 @@ enum iommu_attr {
	DOMAIN_ATTR_MAX,
};

+#define IOMMU_RESV_DIRECT	(1 << 0)
+#define IOMMU_RESV_RESERVED	(1 << 1)
+
/**
 * struct iommu_dm_region - descriptor for a direct mapped memory region
 * @list: Linked list pointers
 * @start: System physical start address of the region
 * @length: Length of the region in bytes
 * @prot: IOMMU Protection flags (READ/WRITE/...)
+ * @type: Type of region (DIRECT, RESERVED)
 */
struct iommu_dm_region {
	struct list_head	list;
	phys_addr_t		start;
	size_t			length;
	int			prot;
+	int			type;
};

#ifdef CONFIG_IOMMU_API
--
2.21.0