[PATCH 6/6] iommu/amd: Lock code paths traversing protection_domain->dev_list

From: Joerg Roedel <joro@8bytes.org>
To: iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>
Cc: Filippo Sironi <sironi@amazon.de>, jroedel@suse.de
Subject: [PATCH 6/6] iommu/amd: Lock code paths traversing protection_domain->dev_list
Date: Wed, 25 Sep 2019 15:23:00 +0200	[thread overview]
Message-ID: <20190925132300.3038-7-joro@8bytes.org> (raw)
In-Reply-To: <20190925132300.3038-1-joro@8bytes.org>

From: Joerg Roedel <jroedel@suse.de>

The traversing of this list requires protection_domain->lock to be taken
to avoid nasty races with attach/detach code. Make sure the lock is held
on all code-paths traversing this list.

Reported-by: Filippo Sironi <sironi@amazon.de>
Fixes: 92d420ec028d ("iommu/amd: Relax locking in dma_ops path")
Signed-off-by: Joerg Roedel <jroedel@suse.de>
---
 drivers/iommu/amd_iommu.c | 25 ++++++++++++++++++++++++-
 1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index bac4e20a5919..9c26976a0f99 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1334,8 +1334,12 @@ static void domain_flush_np_cache(struct protection_domain *domain,
 		dma_addr_t iova, size_t size)
 {
 	if (unlikely(amd_iommu_np_cache)) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&domain->lock, flags);
 		domain_flush_pages(domain, iova, size);
 		domain_flush_complete(domain);
+		spin_unlock_irqrestore(&domain->lock, flags);
 	}
 }
 
@@ -1700,8 +1704,13 @@ static int iommu_map_page(struct protection_domain *dom,
 	ret = 0;
 
 out:
-	if (updated)
+	if (updated) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&dom->lock, flags);
 		update_domain(dom);
+		spin_unlock_irqrestore(&dom->lock, flags);
+	}
 
 	/* Everything flushed out, free pages now */
 	free_page_list(freelist);
@@ -1857,8 +1866,12 @@ static void free_gcr3_table(struct protection_domain *domain)
 
 static void dma_ops_domain_flush_tlb(struct dma_ops_domain *dom)
 {
+	unsigned long flags;
+
+	spin_lock_irqsave(&dom->domain.lock, flags);
 	domain_flush_tlb(&dom->domain);
 	domain_flush_complete(&dom->domain);
+	spin_unlock_irqrestore(&dom->domain.lock, flags);
 }
 
 static void iova_domain_flush_tlb(struct iova_domain *iovad)
@@ -2414,6 +2427,7 @@ static dma_addr_t __map_single(struct device *dev,
 {
 	dma_addr_t offset = paddr & ~PAGE_MASK;
 	dma_addr_t address, start, ret;
+	unsigned long flags;
 	unsigned int pages;
 	int prot = 0;
 	int i;
@@ -2451,8 +2465,10 @@ static dma_addr_t __map_single(struct device *dev,
 		iommu_unmap_page(&dma_dom->domain, start, PAGE_SIZE);
 	}
 
+	spin_lock_irqsave(&dma_dom->domain.lock, flags);
 	domain_flush_tlb(&dma_dom->domain);
 	domain_flush_complete(&dma_dom->domain);
+	spin_unlock_irqrestore(&dma_dom->domain.lock, flags);
 
 	dma_ops_free_iova(dma_dom, address, pages);
 
@@ -2481,8 +2497,12 @@ static void __unmap_single(struct dma_ops_domain *dma_dom,
 	}
 
 	if (amd_iommu_unmap_flush) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&dma_dom->domain.lock, flags);
 		domain_flush_tlb(&dma_dom->domain);
 		domain_flush_complete(&dma_dom->domain);
+		spin_unlock_irqrestore(&dma_dom->domain.lock, flags);
 		dma_ops_free_iova(dma_dom, dma_addr, pages);
 	} else {
 		pages = __roundup_pow_of_two(pages);
@@ -3246,9 +3266,12 @@ static bool amd_iommu_is_attach_deferred(struct iommu_domain *domain,
 static void amd_iommu_flush_iotlb_all(struct iommu_domain *domain)
 {
 	struct protection_domain *dom = to_pdomain(domain);
+	unsigned long flags;
 
+	spin_lock_irqsave(&dom->lock, flags);
 	domain_flush_tlb_pde(dom);
 	domain_flush_complete(dom);
+	spin_unlock_irqrestore(&dom->lock, flags);
 }
 
 static void amd_iommu_iotlb_sync(struct iommu_domain *domain,
-- 
2.17.1

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