linux-kernel - [PATCH] iommu/dma: Setup iova_domain granule for IOMMU_DMA

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Date:   Thu, 13 Apr 2017 04:55:15 -0400
From:   Nate Watterson <nwatters@...eaurora.org>
To:     robin.murphy@....com, Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Cc:     shankerd@...eaurora.org, Nate Watterson <nwatters@...eaurora.org>
Subject: [PATCH] iommu/dma: Setup iova_domain granule for IOMMU_DMA_MSI cookies

Currently, the __iommu_dma_{map/free} functions call iova_{offset/align}
making them unsuitable for use with iommu_domains having an IOMMU_DMA_MSI
cookie since the cookie's iova_domain member, iovad, is uninitialized.

Now that iommu_dma_get_msi_page() calls __iommu_dma_map() regardless
of cookie type, failures are being seen when mapping MSI target
addresses for devices attached to UNMANAGED domains. To work around
this issue, the iova_domain granule for IOMMU_DMA_MSI cookies is
initialized to the value returned by cookie_msi_granule().

Fixes: a44e6657585b ("iommu/dma: Clean up MSI IOVA allocation")
Signed-off-by: Nate Watterson <nwatters@...eaurora.org>
---
 drivers/iommu/dma-iommu.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 8348f366..d7b0816 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -127,6 +127,16 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base)
 
 	cookie->msi_iova = base;
 	domain->iova_cookie = cookie;
+
+	/*
+	 * Setup granule for compatibility with __iommu_dma_{alloc/free} and
+	 * add a compile time check to ensure that writing granule won't
+	 * clobber msi_iova.
+	 */
+	cookie->iovad.granule = cookie_msi_granule(cookie);
+	BUILD_BUG_ON(offsetof(struct iova_domain, granule) <
+			sizeof(cookie->msi_iova));
+
 	return 0;
 }
 EXPORT_SYMBOL(iommu_get_msi_cookie);
-- 
Qualcomm Datacenter Technologies, Inc. on behalf of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux
Foundation Collaborative Project.