Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752312AbbEMGHx (ORCPT ); Wed, 13 May 2015 02:07:53 -0400 Received: from e23smtp07.au.ibm.com ([202.81.31.140]:36492 "EHLO e23smtp07.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751029AbbEMGHv (ORCPT ); Wed, 13 May 2015 02:07:51 -0400 Date: Wed, 13 May 2015 16:06:47 +1000 From: Gavin Shan To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, David Gibson , Benjamin Herrenschmidt , Paul Mackerras , Alex Williamson , Gavin Shan , Wei Yang , linux-kernel@vger.kernel.org Subject: Re: [PATCH kernel v10 07/34] vfio: powerpc/spapr: Check that IOMMU page is fully contained by system page Message-ID: <20150513060647.GA6283@gwshan> Reply-To: Gavin Shan References: <1431358763-24371-1-git-send-email-aik@ozlabs.ru> <1431358763-24371-8-git-send-email-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1431358763-24371-8-git-send-email-aik@ozlabs.ru> User-Agent: Mutt/1.5.23 (2014-03-12) X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15051306-0025-0000-0000-0000017864CA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2351 Lines: 76 On Tue, May 12, 2015 at 01:38:56AM +1000, Alexey Kardashevskiy wrote: >This checks that the TCE table page size is not bigger that the size of >a page we just pinned and going to put its physical address to the table. > >Otherwise the hardware gets unwanted access to physical memory between >the end of the actual page and the end of the aligned up TCE page. > >Since compound_order() and compound_head() work correctly on non-huge >pages, there is no need for additional check whether the page is huge. > >Signed-off-by: Alexey Kardashevskiy >[aw: for the vfio related changes] >Acked-by: Alex Williamson >Reviewed-by: David Gibson Reviewed-by: Gavin Shan Thanks, Gavin >--- >Changes: >v8: changed subject > >v6: >* the helper is simplified to one line > >v4: >* s/tce_check_page_size/tce_page_is_contained/ >--- > drivers/vfio/vfio_iommu_spapr_tce.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > >diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c >index b95fa2b..735b308 100644 >--- a/drivers/vfio/vfio_iommu_spapr_tce.c >+++ b/drivers/vfio/vfio_iommu_spapr_tce.c >@@ -47,6 +47,16 @@ struct tce_container { > bool enabled; > }; > >+static bool tce_page_is_contained(struct page *page, unsigned page_shift) >+{ >+ /* >+ * Check that the TCE table granularity is not bigger than the size of >+ * a page we just found. Otherwise the hardware can get access to >+ * a bigger memory chunk that it should. >+ */ >+ return (PAGE_SHIFT + compound_order(compound_head(page))) >= page_shift; >+} >+ > static int tce_iommu_enable(struct tce_container *container) > { > int ret = 0; >@@ -189,6 +199,12 @@ static long tce_iommu_build(struct tce_container *container, > ret = -EFAULT; > break; > } >+ >+ if (!tce_page_is_contained(page, tbl->it_page_shift)) { >+ ret = -EPERM; >+ break; >+ } >+ > hva = (unsigned long) page_address(page) + offset; > > ret = iommu_tce_build(tbl, entry + i, hva, direction); >-- >2.4.0.rc3.8.gfb3e7d5 > -- 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/