linux-kernel - [PATCH 2/2] iommu/dma: Avoid SAC address trick for PCIe devices

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed,  8 Jul 2020 12:32:42 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     joro@...tes.org
Cc:     hch@....de, iommu@...ts.linux-foundation.org,
        jonathan.lemon@...il.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org, baolu.lu@...ux.intel.com,
        dwmw2@...radead.org, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH 2/2] iommu/dma: Avoid SAC address trick for PCIe devices

As for the intel-iommu implementation, relegate the opportunistic
attempt to allocate a SAC address to the domain of conventional PCI
devices only, to avoid it increasingly causing far more performance
issues than possible benefits on modern PCI Express systems.

Signed-off-by: Robin Murphy <robin.murphy@....com>
---
 drivers/iommu/dma-iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 4959f5df21bd..0ff124f16ad4 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -426,7 +426,8 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
 		dma_limit = min(dma_limit, (u64)domain->geometry.aperture_end);
 
 	/* Try to get PCI devices a SAC address */
-	if (dma_limit > DMA_BIT_MASK(32) && dev_is_pci(dev))
+	if (dma_limit > DMA_BIT_MASK(32) &&
+	    dev_is_pci(dev) && !pci_is_pcie(to_pci_dev(dev)))
 		iova = alloc_iova_fast(iovad, iova_len,
 				       DMA_BIT_MASK(32) >> shift, false);
 
-- 
2.23.0.dirty