iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes

To permit batching of TLB flushes across multiple calls to the IOMMU
driver's ->unmap() implementation, introduce a new structure for
tracking the address range to be flushed and the granularity at which
the flushing is required.

This is hooked into the IOMMU API and its caller are updated to make use
of the new structure. Subsequent patches will plumb this into the IOMMU
drivers as well, but for now the gathering information is ignored.

Signed-off-by: Will Deacon <will@kernel.org>

3 files changed, 36 insertions, 18 deletions

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index a7f9c3edbcb2..80beb1f5994a 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -444,13 +444,18 @@ static void __iommu_dma_unmap(struct device *dev, dma_addr_t dma_addr,
 	struct iommu_dma_cookie *cookie = domain->iova_cookie;
 	struct iova_domain *iovad = &cookie->iovad;
 	size_t iova_off = iova_offset(iovad, dma_addr);
+	struct iommu_iotlb_gather iotlb_gather;
+	size_t unmapped;
 
 	dma_addr -= iova_off;
 	size = iova_align(iovad, size + iova_off);
+	iommu_iotlb_gather_init(&iotlb_gather);
+
+	unmapped = iommu_unmap_fast(domain, dma_addr, size, &iotlb_gather);
+	WARN_ON(unmapped != size);
 
-	WARN_ON(iommu_unmap_fast(domain, dma_addr, size) != size);
 	if (!cookie->fq_domain)
-		iommu_tlb_sync(domain);
+		iommu_tlb_sync(domain, &iotlb_gather);
 	iommu_dma_free_iova(cookie, dma_addr, size);
 }
 
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 6d7b25fe2474..d67222fdfe44 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1862,7 +1862,7 @@ EXPORT_SYMBOL_GPL(iommu_map);
 
 static size_t __iommu_unmap(struct iommu_domain *domain,
 			    unsigned long iova, size_t size,
-			    bool sync)
+			    struct iommu_iotlb_gather *iotlb_gather)
 {
 	const struct iommu_ops *ops = domain->ops;
 	size_t unmapped_page, unmapped = 0;
@@ -1910,9 +1910,6 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
 		unmapped += unmapped_page;
 	}
 
-	if (sync && ops->iotlb_sync)
-		ops->iotlb_sync(domain);
-
 	trace_unmap(orig_iova, size, unmapped);
 	return unmapped;
 }
@@ -1920,14 +1917,22 @@ static size_t __iommu_unmap(struct iommu_domain *domain,
 size_t iommu_unmap(struct iommu_domain *domain,
 		   unsigned long iova, size_t size)
 {
-	return __iommu_unmap(domain, iova, size, true);
+	struct iommu_iotlb_gather iotlb_gather;
+	size_t ret;
+
+	iommu_iotlb_gather_init(&iotlb_gather);
+	ret = __iommu_unmap(domain, iova, size, &iotlb_gather);
+	iommu_tlb_sync(domain, &iotlb_gather);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(iommu_unmap);
 
 size_t iommu_unmap_fast(struct iommu_domain *domain,
-			unsigned long iova, size_t size)
+			unsigned long iova, size_t size,
+			struct iommu_iotlb_gather *iotlb_gather)
 {
-	return __iommu_unmap(domain, iova, size, false);
+	return __iommu_unmap(domain, iova, size, iotlb_gather);
 }
 EXPORT_SYMBOL_GPL(iommu_unmap_fast);
 
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index fad7fd8c167c..ad830abe1021 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -650,12 +650,13 @@ unpin_exit:
 }
 
 static long vfio_sync_unpin(struct vfio_dma *dma, struct vfio_domain *domain,
-				struct list_head *regions)
+			    struct list_head *regions,
+			    struct iommu_iotlb_gather *iotlb_gather)
 {
 	long unlocked = 0;
 	struct vfio_regions *entry, *next;
 
-	iommu_tlb_sync(domain->domain);
+	iommu_tlb_sync(domain->domain, iotlb_gather);
 
 	list_for_each_entry_safe(entry, next, regions, list) {
 		unlocked += vfio_unpin_pages_remote(dma,
@@ -685,13 +686,15 @@ static size_t unmap_unpin_fast(struct vfio_domain *domain,
 			       struct vfio_dma *dma, dma_addr_t *iova,
 			       size_t len, phys_addr_t phys, long *unlocked,
 			       struct list_head *unmapped_list,
-			       int *unmapped_cnt)
+			       int *unmapped_cnt,
+			       struct iommu_iotlb_gather *iotlb_gather)
 {
 	size_t unmapped = 0;
 	struct vfio_regions *entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 
 	if (entry) {
-		unmapped = iommu_unmap_fast(domain->domain, *iova, len);
+		unmapped = iommu_unmap_fast(domain->domain, *iova, len,
+					    iotlb_gather);
 
 		if (!unmapped) {
 			kfree(entry);
@@ -711,8 +714,8 @@ static size_t unmap_unpin_fast(struct vfio_domain *domain,
 	 * or in case of errors.
 	 */
 	if (*unmapped_cnt >= VFIO_IOMMU_TLB_SYNC_MAX || !unmapped) {
-		*unlocked += vfio_sync_unpin(dma, domain,
-					     unmapped_list);
+		*unlocked += vfio_sync_unpin(dma, domain, unmapped_list,
+					     iotlb_gather);
 		*unmapped_cnt = 0;
 	}
 
@@ -743,6 +746,7 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
 	dma_addr_t iova = dma->iova, end = dma->iova + dma->size;
 	struct vfio_domain *domain, *d;
 	LIST_HEAD(unmapped_region_list);
+	struct iommu_iotlb_gather iotlb_gather;
 	int unmapped_region_cnt = 0;
 	long unlocked = 0;
 
@@ -767,6 +771,7 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
 		cond_resched();
 	}
 
+	iommu_iotlb_gather_init(&iotlb_gather);
 	while (iova < end) {
 		size_t unmapped, len;
 		phys_addr_t phys, next;
@@ -795,7 +800,8 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
 		 */
 		unmapped = unmap_unpin_fast(domain, dma, &iova, len, phys,
 					    &unlocked, &unmapped_region_list,
-					    &unmapped_region_cnt);
+					    &unmapped_region_cnt,
+					    &iotlb_gather);
 		if (!unmapped) {
 			unmapped = unmap_unpin_slow(domain, dma, &iova, len,
 						    phys, &unlocked);
@@ -806,8 +812,10 @@ static long vfio_unmap_unpin(struct vfio_iommu *iommu, struct vfio_dma *dma,
 
 	dma->iommu_mapped = false;
 
-	if (unmapped_region_cnt)
-		unlocked += vfio_sync_unpin(dma, domain, &unmapped_region_list);
+	if (unmapped_region_cnt) {
+		unlocked += vfio_sync_unpin(dma, domain, &unmapped_region_list,
+					    &iotlb_gather);
+	}
 
 	if (do_accounting) {
 		vfio_lock_acct(dma, -unlocked, true);