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

["Sironi, Filippo via iommu" <iommu@lists.linux-foundation.org>]

> On 25. Sep 2019, at 06:23, Joerg Roedel <joro@8bytes.org> wrote:
> 
> 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
> 

Reviewed-by: Filippo Sironi <sironi@amazon.de>



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