linux-kernel - [PATCH 3/5] iommu/amd: Hold the domain lock when calling __unmap

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Date:   Tue, 10 Sep 2019 19:49:23 +0200
From:   Filippo Sironi <sironi@...zon.de>
To:     sironi@...zon.de, joro@...tes.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/5] iommu/amd: Hold the domain lock when calling __unmap_single

__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@...zon.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