[PATCH 2/5] iommu/amd: Hold the domain lock when calling __map_single

Filippo Sironi
2019-09-10T17:50:14Z

__map_single makes several calls to __domain_flush_pages, which
traverses the device list that is protected by the domain lock.

Also, this is in line with the comment on top of __map_single, which
says that the domain lock should be held when calling.

Signed-off-by: Filippo Sironi <sironi@amazon.de>
---
drivers/iommu/amd_iommu.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index f026a8c2b218..8e3664821b3c 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2482,6 +2482,8 @@ static dma_addr_t map_page(struct device *dev, struct page *page,
struct protection_domain *domain;
struct dma_ops_domain *dma_dom;
u64 dma_mask;
+ unsigned long flags;
+ dma_addr_t dma_addr;

domain = get_domain(dev);
if (PTR_ERR(domain) == -EINVAL)
@@ -2492,7 +2494,10 @@ static dma_addr_t map_page(struct device *dev, struct page *page,
dma_mask = *dev->dma_mask;
dma_dom = to_dma_ops_domain(domain);

- return __map_single(dev, dma_dom, paddr, size, dir, dma_mask);
+ spin_lock_irqsave(&domain->lock, flags);
+ dma_addr = __map_single(dev, dma_dom, paddr, size, dir, dma_mask);
+ spin_unlock_irqrestore(&domain->lock, flags);
+ return dma_addr;
}

/*
@@ -2663,6 +2668,7 @@ static void *alloc_coherent(struct device *dev, size_t size,
struct protection_domain *domain;
struct dma_ops_domain *dma_dom;
struct page *page;
+ unsigned long flags;

domain = get_domain(dev);
if (PTR_ERR(domain) == -EINVAL) {
@@ -2692,8 +2698,10 @@ static void *alloc_coherent(struct device *dev, size_t size,
if (!dma_mask)
dma_mask = *dev->dma_mask;

+ spin_lock_irqsave(&domain->lock, flags);
*dma_addr = __map_single(dev, dma_dom, page_to_phys(page),
size, DMA_BIDIRECTIONAL, dma_mask);
+ spin_unlock_irqrestore(&domain->lock, flags);

if (*dma_addr == DMA_MAPPING_ERROR)
goto out_free;
--
2.7.4