Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752985AbbDBDqV (ORCPT ); Wed, 1 Apr 2015 23:46:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49226 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752036AbbDBDqT (ORCPT ); Wed, 1 Apr 2015 23:46:19 -0400 Message-ID: <1427946378.5567.340.camel@redhat.com> Subject: Re: [PATCH kernel v7 04/31] vfio: powerpc/spapr: Use it_page_size From: Alex Williamson To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, Benjamin Herrenschmidt , Paul Mackerras , linux-kernel@vger.kernel.org Date: Wed, 01 Apr 2015 21:46:18 -0600 In-Reply-To: <551CBA14.7080707@ozlabs.ru> References: <1427468115-2224-1-git-send-email-aik@ozlabs.ru> <1427468115-2224-5-git-send-email-aik@ozlabs.ru> <1427924904.5567.303.camel@redhat.com> <551CA9D7.2060804@ozlabs.ru> <1427943033.5567.329.camel@redhat.com> <551CBA14.7080707@ozlabs.ru> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3499 Lines: 75 On Thu, 2015-04-02 at 14:40 +1100, Alexey Kardashevskiy wrote: > On 04/02/2015 01:50 PM, Alex Williamson wrote: > > On Thu, 2015-04-02 at 13:30 +1100, Alexey Kardashevskiy wrote: > >> On 04/02/2015 08:48 AM, Alex Williamson wrote: > >>> On Sat, 2015-03-28 at 01:54 +1100, Alexey Kardashevskiy wrote: > >>>> This makes use of the it_page_size from the iommu_table struct > >>>> as page size can differ. > >>>> > >>>> This replaces missing IOMMU_PAGE_SHIFT macro in commented debug code > >>>> as recently introduced IOMMU_PAGE_XXX macros do not include > >>>> IOMMU_PAGE_SHIFT. > >>>> > >>>> Signed-off-by: Alexey Kardashevskiy > >>>> Reviewed-by: David Gibson > >>>> --- > >>>> drivers/vfio/vfio_iommu_spapr_tce.c | 26 +++++++++++++------------- > >>>> 1 file changed, 13 insertions(+), 13 deletions(-) > >>>> > >>>> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c > >>>> index f835e63..8bbee22 100644 > >>>> --- a/drivers/vfio/vfio_iommu_spapr_tce.c > >>>> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c > >>>> @@ -91,7 +91,7 @@ static int tce_iommu_enable(struct tce_container *container) > >>>> * enforcing the limit based on the max that the guest can map. > >>>> */ > >>>> down_write(¤t->mm->mmap_sem); > >>>> - npages = (tbl->it_size << IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT; > >>>> + npages = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT; > >>>> locked = current->mm->locked_vm + npages; > >>>> lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; > >>>> if (locked > lock_limit && !capable(CAP_IPC_LOCK)) { > >>>> @@ -120,7 +120,7 @@ static void tce_iommu_disable(struct tce_container *container) > >>>> > >>>> down_write(¤t->mm->mmap_sem); > >>>> current->mm->locked_vm -= (container->tbl->it_size << > >>>> - IOMMU_PAGE_SHIFT_4K) >> PAGE_SHIFT; > >>>> + container->tbl->it_page_shift) >> PAGE_SHIFT; > >>>> up_write(¤t->mm->mmap_sem); > >>>> } > >>>> > >>>> @@ -222,7 +222,7 @@ static long tce_iommu_build(struct tce_container *container, > >>>> tce, ret); > >>>> break; > >>>> } > >>>> - tce += IOMMU_PAGE_SIZE_4K; > >>>> + tce += IOMMU_PAGE_SIZE(tbl); > >>> > >>> > >>> Is PAGE_SIZE ever smaller than IOMMU_PAGE_SIZE(tbl)? IOW, can the page > >>> we got from get_user_pages_fast() ever not completely fill the tce > >>> entry? > >> > >> > >> Yes. IOMMU_PAGE_SIZE is 4K/64K/16M (16M is with huge pages enabled in QEMU > >> with -mempath), PAGE_SIZE is 4K/64K (normally 64K). > > > > Isn't that a problem then that you're filling the tce with processor > > page sizes via get_user_pages_fast(), but incrementing the tce by by > > IOMMU page size? For example, if PAGE_SIZE = 4K and IOMMU_PAGE_SIZE != > > 4K have we really pinned all of the memory backed by the tce?Where do > > you make sure the 4K page is really contiguous for the IOMMU page? > > > Aaaah. This is just not supported. Instead, after the previous patch > ("vfio: powerpc/spapr: Check that TCE page size is equal to it_page_size", > which need fixed subject), tce_page_is_contained(page4K, 64K) will return > false and the caller - tce_iommu_build() - will return -EPERM. Ok, makes sense. Thanks -- 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/