1 files changed, 21 insertions, 4 deletions

diff --git a/drivers/iommu/amd/io_pgtable.c b/drivers/iommu/amd/io_pgtable.c
index a91e71f981ef..70c2f5b1631b 100644
--- a/drivers/iommu/amd/io_pgtable.c
+++ b/drivers/iommu/amd/io_pgtable.c
@@ -17,6 +17,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/dma-mapping.h>
+#include <linux/seqlock.h>
 
 #include <asm/barrier.h>
 
@@ -130,8 +131,11 @@ static bool increase_address_space(struct amd_io_pgtable *pgtable,
 
 	*pte = PM_LEVEL_PDE(pgtable->mode, iommu_virt_to_phys(pgtable->root));
 
+	write_seqcount_begin(&pgtable->seqcount);
 	pgtable->root  = pte;
 	pgtable->mode += 1;
+	write_seqcount_end(&pgtable->seqcount);
+
 	amd_iommu_update_and_flush_device_table(domain);
 
 	pte = NULL;
@@ -153,6 +157,7 @@ static u64 *alloc_pte(struct amd_io_pgtable *pgtable,
 {
 	unsigned long last_addr = address + (page_size - 1);
 	struct io_pgtable_cfg *cfg = &pgtable->pgtbl.cfg;
+	unsigned int seqcount;
 	int level, end_lvl;
 	u64 *pte, *page;
 
@@ -170,8 +175,14 @@ static u64 *alloc_pte(struct amd_io_pgtable *pgtable,
 	}
 
 
-	level   = pgtable->mode - 1;
-	pte     = &pgtable->root[PM_LEVEL_INDEX(level, address)];
+	do {
+		seqcount = read_seqcount_begin(&pgtable->seqcount);
+
+		level   = pgtable->mode - 1;
+		pte     = &pgtable->root[PM_LEVEL_INDEX(level, address)];
+	} while (read_seqcount_retry(&pgtable->seqcount, seqcount));
+
+
 	address = PAGE_SIZE_ALIGN(address, page_size);
 	end_lvl = PAGE_SIZE_LEVEL(page_size);
 
@@ -249,6 +260,7 @@ static u64 *fetch_pte(struct amd_io_pgtable *pgtable,
 		      unsigned long *page_size)
 {
 	int level;
+	unsigned int seqcount;
 	u64 *pte;
 
 	*page_size = 0;
@@ -256,8 +268,12 @@ static u64 *fetch_pte(struct amd_io_pgtable *pgtable,
 	if (address > PM_LEVEL_SIZE(pgtable->mode))
 		return NULL;
 
-	level	   =  pgtable->mode - 1;
-	pte	   = &pgtable->root[PM_LEVEL_INDEX(level, address)];
+	do {
+		seqcount = read_seqcount_begin(&pgtable->seqcount);
+		level	   =  pgtable->mode - 1;
+		pte	   = &pgtable->root[PM_LEVEL_INDEX(level, address)];
+	} while (read_seqcount_retry(&pgtable->seqcount, seqcount));
+
 	*page_size =  PTE_LEVEL_PAGE_SIZE(level);
 
 	while (level > 0) {
@@ -541,6 +557,7 @@ static struct io_pgtable *v1_alloc_pgtable(struct io_pgtable_cfg *cfg, void *coo
 	if (!pgtable->root)
 		return NULL;
 	pgtable->mode = PAGE_MODE_3_LEVEL;
+	seqcount_init(&pgtable->seqcount);
 
 	cfg->pgsize_bitmap  = amd_iommu_pgsize_bitmap;
 	cfg->ias            = IOMMU_IN_ADDR_BIT_SIZE;