Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756867AbdGLHVV (ORCPT ); Wed, 12 Jul 2017 03:21:21 -0400 Received: from verein.lst.de ([213.95.11.211]:56052 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756647AbdGLHVT (ORCPT ); Wed, 12 Jul 2017 03:21:19 -0400 Date: Wed, 12 Jul 2017 09:21:18 +0200 From: Christoph Hellwig To: Tushar Dave Cc: davem@davemloft.net, chris.hyser@oracle.com, sowmini.varadhan@oracle.com, egtvedt@samfundet.no, dan.carpenter@oracle.com, krzk@kernel.org, bart.vanassche@sandisk.com, sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org, hch@lst.de, mroos@linux.ee Subject: Re: [sparc-next] SPARC64: Fix sun4v DMA panic Message-ID: <20170712072118.GB5739@lst.de> References: <1499808887-31483-1-git-send-email-tushar.n.dave@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1499808887-31483-1-git-send-email-tushar.n.dave@oracle.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1612 Lines: 48 On Tue, Jul 11, 2017 at 02:34:47PM -0700, Tushar Dave wrote: > 64bit DMA only supported on sun4v equipped with ATU IOMMU HW. > 'Commit b02c2b0bfd7ae ("sparc: remove arch specific dma_supported > implementations")' introduced a code that incorrectly allow > dma_supported() to succeed for 64bit dma mask even if system doesn't > have ATU IOMMU. This results into panic. > > Fix it. > > Reported-by: Meelis Roos > Signed-off-by: Tushar Dave > --- > arch/sparc/kernel/pci_sun4v.c | 12 +++++++----- > 1 file changed, 7 insertions(+), 5 deletions(-) > > diff --git a/arch/sparc/kernel/pci_sun4v.c b/arch/sparc/kernel/pci_sun4v.c > index 24f21c7..f10e2f7 100644 > --- a/arch/sparc/kernel/pci_sun4v.c > +++ b/arch/sparc/kernel/pci_sun4v.c > @@ -673,12 +673,14 @@ static void dma_4v_unmap_sg(struct device *dev, struct scatterlist *sglist, > static int dma_4v_supported(struct device *dev, u64 device_mask) > { > struct iommu *iommu = dev->archdata.iommu; > - u64 dma_addr_mask; > + u64 dma_addr_mask = iommu->dma_addr_mask; > > - if (device_mask > DMA_BIT_MASK(32) && iommu->atu) > - dma_addr_mask = iommu->atu->dma_addr_mask; > - else > - dma_addr_mask = iommu->dma_addr_mask; > + if (device_mask > DMA_BIT_MASK(32)) { > + if (iommu->atu) > + dma_addr_mask = iommu->atu->dma_addr_mask; > + else > + return 0; > + } This would be more readable as: if (device_mask > DMA_BIT_MASK(32)) { if (!iommu->atu) return 0; dma_addr_mask = iommu->atu->dma_addr_mask; } But except for that it looks fine to me: Reviewed-by: Christoph Hellwig