linux-kernel - [PATCH v3 1/6] iommu/dma: Disable get_sgtable for granule > PAGE

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Date:   Tue, 19 Oct 2021 18:37:32 +0200
From:   Sven Peter <sven@...npeter.dev>
To:     iommu@...ts.linux-foundation.org,
        Robin Murphy <robin.murphy@....com>
Cc:     Sven Peter <sven@...npeter.dev>, Joerg Roedel <joro@...tes.org>,
        Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...nel.org>,
        Marc Zyngier <maz@...nel.org>,
        Mohamed Mediouni <mohamed.mediouni@...amail.com>,
        Alexander Graf <graf@...zon.com>,
        Hector Martin <marcan@...can.st>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/6] iommu/dma: Disable get_sgtable for granule > PAGE_SIZE

While this function *probably* works correctly without any changes for
granule > PAGE_SIZE I don't have any code to actually test it and cannot
reason about how the function is supposed to work.
Disable it instead until we run into a use case where it's required.

Signed-off-by: Sven Peter <sven@...npeter.dev>
---
 drivers/iommu/dma-iommu.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index de5040b65529..17f25632a0d6 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1249,9 +1249,15 @@ static int iommu_dma_get_sgtable(struct device *dev, struct sg_table *sgt,
 		void *cpu_addr, dma_addr_t dma_addr, size_t size,
 		unsigned long attrs)
 {
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
 	struct page *page;
 	int ret;
 
+	if (iovad->granule > PAGE_SIZE)
+		return -ENXIO;
+
 	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr)) {
 		struct page **pages = dma_common_find_pages(cpu_addr);
 
-- 
2.25.1