Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756942Ab3JNRKc (ORCPT ); Mon, 14 Oct 2013 13:10:32 -0400 Received: from cam-admin0.cambridge.arm.com ([217.140.96.50]:50525 "EHLO cam-admin0.cambridge.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756335Ab3JNRKb (ORCPT ); Mon, 14 Oct 2013 13:10:31 -0400 Date: Mon, 14 Oct 2013 18:09:48 +0100 From: Will Deacon To: Antonios Motakis Cc: Joerg Roedel , "moderated list:ARM SMMU DRIVER" , "open list:IOMMU DRIVERS" , open list , "kvmarm@lists.cs.columbia.edu" , "tech@virtualopensystems.com" , "agraf@suse.de" , "B08248@freescale.com" Subject: Re: [PATCH 2/2] ARM: SMMU: return NULL on error in arm_smmu_iova_to_phys Message-ID: <20131014170948.GS10491@mudshark.cambridge.arm.com> References: <1381497887-14586-1-git-send-email-a.motakis@virtualopensystems.com> <1381497887-14586-2-git-send-email-a.motakis@virtualopensystems.com> <20131014124837.GD10491@mudshark.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2115 Lines: 47 On Mon, Oct 14, 2013 at 04:17:51PM +0100, Antonios Motakis wrote: > On Mon, Oct 14, 2013 at 2:48 PM, Will Deacon wrote: > > On Fri, Oct 11, 2013 at 02:24:47PM +0100, Antonios Motakis wrote: > >> The return value of arm_smmu_iova_to_phys is directly passed to the > >> user of the IOMMU API via iommu_iova_to_phys; however the ARM SMMU > >> driver returns -EINVAL on error, which is not consistent with the > >> rest of the drivers implementing the IOMMU API. VFIO also relies on > >> the call returning NULL when a page has not been mapped already. > >> > >> Signed-off-by: Antonios Motakis > >> --- > >> drivers/iommu/arm-smmu.c | 5 +---- > >> 1 file changed, 1 insertion(+), 4 deletions(-) > >> > >> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > >> index 8b71332..fe81b20 100644 > >> --- a/drivers/iommu/arm-smmu.c > >> +++ b/drivers/iommu/arm-smmu.c > >> @@ -1480,10 +1480,7 @@ static phys_addr_t arm_smmu_iova_to_phys(struct iommu_domain *domain, > >> > >> err_unlock: > >> spin_unlock(&smmu_domain->lock); > >> - dev_warn(smmu->dev, > >> - "invalid (corrupt?) page tables detected for iova 0x%llx\n", > >> - (unsigned long long)iova); > >> - return -EINVAL; > >> + return NULL; > > > > Why are you removing the warning message? > > VFIO will exercise this code path every time when mapping DMA memory. > This is normal and VFIO *expects* the function to fail - it is only if > the function succeeds that VFIO needs to back down from the DMA > mapping and fail. > > This means that there would be a warning every time a VFIO user maps > some memory for DMA use, even though nothing went wrong. Ok, in which case it might be worth reworking arm_smmu_iova_to_phys to treat {pgd,pud,pmd,pte}_none different from {pgd,pud,pmd,pte}_bad. Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/