[PATCH 3/5] iommu/amd: Hold the domain lock when calling __unmap_single

Filippo Sironi
2019-09-10T17:55:21Z

__unmap_single makes several calls to __domain_flush_pages, which
traverses the device list that is protected by the domain lock.
__attach_device and __detach_device).

Also, this is in line with the comment on top of __unmap_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 | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 8e3664821b3c..d4f25767622e 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2508,6 +2508,7 @@ static void unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,
{
struct protection_domain *domain;
struct dma_ops_domain *dma_dom;
+ unsigned long flags;

domain = get_domain(dev);
if (IS_ERR(domain))
@@ -2515,7 +2516,9 @@ static void unmap_page(struct device *dev, dma_addr_t dma_addr, size_t size,

dma_dom = to_dma_ops_domain(domain);

+ spin_lock_irqsave(&domain->lock, flags);
__unmap_single(dma_dom, dma_addr, size, dir);
+ spin_unlock_irqrestore(&domain->lock, flags);
}

static int sg_num_pages(struct device *dev,
@@ -2645,6 +2648,7 @@ static void unmap_sg(struct device *dev, struct scatterlist *sglist,
struct dma_ops_domain *dma_dom;
unsigned long startaddr;
int npages;
+ unsigned long flags;

domain = get_domain(dev);
if (IS_ERR(domain))
@@ -2654,7 +2658,9 @@ static void unmap_sg(struct device *dev, struct scatterlist *sglist,
dma_dom = to_dma_ops_domain(domain);
npages = sg_num_pages(dev, sglist, nelems);

+ spin_lock_irqsave(&domain->lock, flags);
__unmap_single(dma_dom, startaddr, npages << PAGE_SHIFT, dir);
+ spin_unlock_irqrestore(&domain->lock, flags);
}

/*
@@ -2726,6 +2732,7 @@ static void free_coherent(struct device *dev, size_t size,
struct protection_domain *domain;
struct dma_ops_domain *dma_dom;
struct page *page;
+ unsigned long flags;

page = virt_to_page(virt_addr);
size = PAGE_ALIGN(size);
@@ -2736,7 +2743,9 @@ static void free_coherent(struct device *dev, size_t size,

dma_dom = to_dma_ops_domain(domain);

+ spin_lock_irqsave(&domain->lock, flags);
__unmap_single(dma_dom, dma_addr, size, DMA_BIDIRECTIONAL);
+ spin_unlock_irqrestore(&domain->lock, flags);

free_mem:
if (!dma_release_from_contiguous(dev, page, size >> PAGE_SHIFT))
--
2.7.4