From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C143C433DF for ; Mon, 17 Aug 2020 10:20:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E53492078A for ; Mon, 17 Aug 2020 10:20:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727859AbgHQKU2 (ORCPT ); Mon, 17 Aug 2020 06:20:28 -0400 Received: from verein.lst.de ([213.95.11.211]:56177 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726165AbgHQKU1 (ORCPT ); Mon, 17 Aug 2020 06:20:27 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 46FC568B05; Mon, 17 Aug 2020 12:20:21 +0200 (CEST) Date: Mon, 17 Aug 2020 12:20:20 +0200 From: Christoph Hellwig To: Thiago Jung Bauermann Cc: iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Christoph Hellwig , Marek Szyprowski , Robin Murphy , Michael Ellerman , Ram Pai , Satheesh Rajendran , Mike Rapoport Subject: Re: [PATCH] swiotlb: Allow allocating buffer anywhere in memory Message-ID: <20200817102020.GD25336@lst.de> References: <20200815204536.663801-1-bauerman@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200815204536.663801-1-bauerman@linux.ibm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 15, 2020 at 05:45:36PM -0300, Thiago Jung Bauermann wrote: > POWER secure guests (i.e., guests which use the Protection Execution > Facility) need to use SWIOTLB to be able to do I/O with the hypervisor, but > they don't need the SWIOTLB memory to be in low addresses since the > hypervisor doesn't have any addressing limitation. > > This solves a SWIOTLB initialization problem we are seeing in secure guests > with 128 GB of RAM: they are configured with 4 GB of crashkernel reserved > memory, which leaves no space for SWIOTLB in low addresses. What about just open coding the allocation and using swiotlb_init_with_tbl? > > Signed-off-by: Thiago Jung Bauermann > --- > arch/powerpc/mm/mem.c | 7 ++++++- > include/linux/swiotlb.h | 8 +++++++- > kernel/dma/swiotlb.c | 10 +++++++--- > 3 files changed, 20 insertions(+), 5 deletions(-) > > Normally I would split changes like this into one patch touching generic > code and another for the arch-specific part, but in this case I thought it > would be unneeded complexity. I can split though if people prefer it that > way. > > diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c > index c2c11eb8dcfc..13f2e3aff8b5 100644 > --- a/arch/powerpc/mm/mem.c > +++ b/arch/powerpc/mm/mem.c > @@ -50,6 +50,7 @@ > #include > #include > #include > +#include > > #include > > @@ -290,7 +291,11 @@ void __init mem_init(void) > * back to to-down. > */ > memblock_set_bottom_up(true); > - swiotlb_init(0); > + /* > + * SVM guests can use the SWIOTLB wherever it is in memory, > + * even if not DMA-able. > + */ > + swiotlb_init_anywhere(0, is_secure_guest()); > #endif > > high_memory = (void *) __va(max_low_pfn * PAGE_SIZE); > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 046bb94bd4d6..433f3dbb35b5 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -29,7 +29,13 @@ enum swiotlb_force { > */ > #define IO_TLB_SHIFT 11 > > -extern void swiotlb_init(int verbose); > +void __init swiotlb_init_anywhere(int verbose, bool allocate_anywhere); > + > +static inline void swiotlb_init(int verbose) > +{ > + swiotlb_init_anywhere(verbose, false); > +} > + > int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose); > extern unsigned long swiotlb_nr_tbl(void); > unsigned long swiotlb_size_or_default(void); > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index c19379fabd20..27070aa59e34 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -244,7 +244,7 @@ int __init swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose) > * structures for the software IO TLB used to implement the DMA API. > */ > void __init > -swiotlb_init(int verbose) > +swiotlb_init_anywhere(int verbose, bool allocate_anywhere) > { > size_t default_size = IO_TLB_DEFAULT_SIZE; > unsigned char *vstart; > @@ -257,8 +257,12 @@ swiotlb_init(int verbose) > > bytes = io_tlb_nslabs << IO_TLB_SHIFT; > > - /* Get IO TLB memory from the low pages */ > - vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE); > + if (allocate_anywhere) > + vstart = memblock_alloc(PAGE_ALIGN(bytes), PAGE_SIZE); > + else > + /* Get IO TLB memory from the low pages */ > + vstart = memblock_alloc_low(PAGE_ALIGN(bytes), PAGE_SIZE); > + > if (vstart && !swiotlb_init_with_tbl(vstart, io_tlb_nslabs, verbose)) > return; > ---end quoted text---