From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 644771A020A for ; Wed, 11 Mar 2015 10:03:33 +1100 (AEDT) Message-ID: <1426028606.25026.86.camel@redhat.com> Subject: Re: [PATCH v5 03/29] vfio: powerpc/spapr: Check that TCE page size is equal to it_page_size From: Alex Williamson To: Alexey Kardashevskiy Date: Tue, 10 Mar 2015 17:03:26 -0600 In-Reply-To: <54FF76F4.5020503@ozlabs.ru> References: <1425910045-26167-1-git-send-email-aik@ozlabs.ru> <1425910045-26167-4-git-send-email-aik@ozlabs.ru> <1426017408.25026.79.camel@redhat.com> <54FF76F4.5020503@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org, kvm@vger.kernel.org, Paul Mackerras , linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2015-03-11 at 09:57 +1100, Alexey Kardashevskiy wrote: > On 03/11/2015 06:56 AM, Alex Williamson wrote: > > On Tue, 2015-03-10 at 01:06 +1100, 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 > >> --- > >> Changes: > >> v4: > >> * s/tce_check_page_size/tce_page_is_contained/ > >> --- > >> drivers/vfio/vfio_iommu_spapr_tce.c | 22 ++++++++++++++++++++++ > >> 1 file changed, 22 insertions(+) > >> > >> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c > >> index 756831f..91e7599 100644 > >> --- a/drivers/vfio/vfio_iommu_spapr_tce.c > >> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > >> @@ -49,6 +49,22 @@ struct tce_container { > >> bool enabled; > >> }; > >> > >> +static bool tce_page_is_contained(struct page *page, unsigned page_shift) > >> +{ > >> + unsigned 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. > >> + */ > >> + shift = PAGE_SHIFT + compound_order(compound_head(page)); > >> + if (shift >= page_shift) > >> + return true; > >> + > >> + return false; > > > > nit, simplified: > > > > return (PAGE_SHIFT + compound_order(compound_head(page) >= page_shift); > > This won't be "bool" though. Yes, it will. > This will (I'll do this) > > shift = PAGE_SHIFT + compound_order(compound_head(page)); > return (shift >= page_shift); > > > > > > > >> +} > >> + > >> static int tce_iommu_enable(struct tce_container *container) > >> { > >> int ret = 0; > >> @@ -197,6 +213,12 @@ 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) + > >> (tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK); > >> > > > > > > > >