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=-11.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 742C9C388F7 for ; Wed, 4 Nov 2020 22:14:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0AA0C20870 for ; Wed, 4 Nov 2020 22:14:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="NfpCC68e" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731941AbgKDWOJ (ORCPT ); Wed, 4 Nov 2020 17:14:09 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:39094 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726777AbgKDWOI (ORCPT ); Wed, 4 Nov 2020 17:14:08 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0A4M9ZdN011988; Wed, 4 Nov 2020 22:13:17 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2020-01-29; bh=+MsunikMfk3zwmlZ0LSPh2GGzl34k8yIm00JFMmjECY=; b=NfpCC68eNlmGeU1hKsxqcDfxcfw1IuPh7xNLDlhbpmAM+CmNo9c2I9fIxeG7wI7T1gZm OTIquOzjUJ8PTaP2G7GJ3JcjGpPAPtSKgAm3ZLxerSyHrGSLA/w0lwP+rmmY4Dh2YhXa Vahgvweji9X+c2JcGxz1qC3PPth2+RkrUG4Fizb3AcdzH9U1LGzUeLmcC9zc0oib0Q8Z N+duXDwDHngkEhWcrMG6cILiebYDUkWa9klUqyyMOsTK8cR9s1imTmAzqz7srO1vFw9m Z1VJlXU+3+9Mp7s0p+fw/hybPBoJ9hWPpMmmF1Viljmrxdgeb6nHwaSWgmZzD3/MwLJj sA== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by aserp2130.oracle.com with ESMTP id 34hhb295cc-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Wed, 04 Nov 2020 22:13:17 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 0A4MAkn6172262; Wed, 4 Nov 2020 22:13:16 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userp3020.oracle.com with ESMTP id 34hw0g8t1t-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 04 Nov 2020 22:13:16 +0000 Received: from abhmp0002.oracle.com (abhmp0002.oracle.com [141.146.116.8]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 0A4MD7KL001316; Wed, 4 Nov 2020 22:13:07 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 04 Nov 2020 14:13:06 -0800 Received: by char.us.oracle.com (Postfix, from userid 1000) id 312A86A00F4; Wed, 4 Nov 2020 17:14:53 -0500 (EST) Date: Wed, 4 Nov 2020 17:14:52 -0500 From: Konrad Rzeszutek Wilk To: Ashish Kalra Cc: hch@lst.de, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, x86@kernel.org, luto@kernel.org, peterz@infradead.org, dave.hansen@linux-intel.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, brijesh.singh@amd.com, Thomas.Lendacky@amd.com, ssg.sos.patches@amd.com Subject: Re: [PATCH v3] swiotlb: Adjust SWIOTBL bounce buffer size for SEV guests. Message-ID: <20201104221452.GA26079@char.us.oracle.com> References: <20201104220804.21026-1-Ashish.Kalra@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201104220804.21026-1-Ashish.Kalra@amd.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9795 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 mlxlogscore=999 phishscore=0 bulkscore=0 spamscore=0 malwarescore=0 mlxscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011040157 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9795 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 phishscore=0 suspectscore=0 clxscore=1011 mlxlogscore=999 impostorscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 spamscore=0 priorityscore=1501 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2011040157 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 04, 2020 at 10:08:04PM +0000, Ashish Kalra wrote: > From: Ashish Kalra > > For SEV, all DMA to and from guest has to use shared > (un-encrypted) pages. SEV uses SWIOTLB to make this > happen without requiring changes to device drivers. > However, depending on workload being run, the default > 64MB of SWIOTLB might not be enough and SWIOTLB > may run out of buffers to use for DMA, resulting > in I/O errors and/or performance degradation for > high I/O workloads. > > Increase the default size of SWIOTLB for SEV guests > using a minimum value of 128MB and a maximum value 64MB for a 1GB VM is not enough? > of 512MB, determining on amount of provisioned guest I like the implementation on how this is done.. but the choices of memory and how much seems very much random. Could there be some math behind this? > memory. > > Using late_initcall() interface to invoke > swiotlb_adjust() does not work as the size > adjustment needs to be done before mem_encrypt_init() > and reserve_crashkernel() which use the allocated > SWIOTLB buffer size, hence calling it explicitly > from setup_arch(). > > The SWIOTLB default size adjustment is added as an > architecture specific interface/callback to allow > architectures such as those supporting memory > encryption to adjust/expand SWIOTLB size for their > use. > > Signed-off-by: Ashish Kalra > --- > arch/x86/kernel/setup.c | 2 ++ > arch/x86/mm/mem_encrypt.c | 42 +++++++++++++++++++++++++++++++++++++++ > include/linux/swiotlb.h | 1 + > kernel/dma/swiotlb.c | 27 +++++++++++++++++++++++++ > 4 files changed, 72 insertions(+) > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > index 3511736fbc74..b073d58dd4a3 100644 > --- a/arch/x86/kernel/setup.c > +++ b/arch/x86/kernel/setup.c > @@ -1166,6 +1166,8 @@ void __init setup_arch(char **cmdline_p) > if (boot_cpu_has(X86_FEATURE_GBPAGES)) > hugetlb_cma_reserve(PUD_SHIFT - PAGE_SHIFT); > > + swiotlb_adjust(); > + > /* > * Reserve memory for crash kernel after SRAT is parsed so that it > * won't consume hotpluggable memory. > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > index 3f248f0d0e07..e0deb157cddd 100644 > --- a/arch/x86/mm/mem_encrypt.c > +++ b/arch/x86/mm/mem_encrypt.c > @@ -489,7 +489,49 @@ static void print_mem_encrypt_feature_info(void) > pr_cont("\n"); > } > > +#define TOTAL_MEM_1G 0x40000000UL > +#define TOTAL_MEM_4G 0x100000000UL > + > +#define SIZE_128M (128UL<<20) > +#define SIZE_256M (256UL<<20) > +#define SIZE_512M (512UL<<20) > + > /* Architecture __weak replacement functions */ > +unsigned long __init arch_swiotlb_adjust(unsigned long iotlb_default_size) > +{ > + unsigned long size = 0; > + > + /* > + * For SEV, all DMA has to occur via shared/unencrypted pages. > + * SEV uses SWOTLB to make this happen without changing device > + * drivers. However, depending on the workload being run, the > + * default 64MB of SWIOTLB may not be enough & SWIOTLB may > + * run out of buffers for DMA, resulting in I/O errors and/or > + * performance degradation especially with high I/O workloads. > + * Increase the default size of SWIOTLB for SEV guests using > + * a minimum value of 128MB and a maximum value of 512MB, > + * depending on amount of provisioned guest memory. > + */ > + if (sev_active()) { > + phys_addr_t total_mem = memblock_phys_mem_size(); > + > + if (total_mem <= TOTAL_MEM_1G) > + size = clamp(iotlb_default_size * 2, SIZE_128M, > + SIZE_128M); > + else if (total_mem <= TOTAL_MEM_4G) > + size = clamp(iotlb_default_size * 4, SIZE_256M, > + SIZE_256M); > + else > + size = clamp(iotlb_default_size * 8, SIZE_512M, > + SIZE_512M); > + > + pr_info("SEV adjusted max SWIOTLB size = %luMB", > + size >> 20); > + } > + > + return size; > +} > + > void __init mem_encrypt_init(void) > { > if (!sme_me_mask) > diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h > index 046bb94bd4d6..01ae6d891327 100644 > --- a/include/linux/swiotlb.h > +++ b/include/linux/swiotlb.h > @@ -33,6 +33,7 @@ extern void swiotlb_init(int verbose); > 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); > +extern void __init swiotlb_adjust(void); > extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs); > extern void __init swiotlb_update_mem_attributes(void); > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index c19379fabd20..66a9e627bb51 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -163,6 +163,33 @@ unsigned long swiotlb_size_or_default(void) > return size ? size : (IO_TLB_DEFAULT_SIZE); > } > > +unsigned long __init __weak arch_swiotlb_adjust(unsigned long size) > +{ > + return 0; > +} > + > +void __init swiotlb_adjust(void) > +{ > + unsigned long size; > + > + /* > + * If swiotlb parameter has not been specified, give a chance to > + * architectures such as those supporting memory encryption to > + * adjust/expand SWIOTLB size for their use. > + */ > + if (!io_tlb_nslabs) { > + size = arch_swiotlb_adjust(IO_TLB_DEFAULT_SIZE); > + if (size) { > + size = ALIGN(size, 1 << IO_TLB_SHIFT); > + io_tlb_nslabs = size >> IO_TLB_SHIFT; > + io_tlb_nslabs = ALIGN(io_tlb_nslabs, IO_TLB_SEGSIZE); > + > + pr_info("architecture adjusted SWIOTLB slabs = %lu\n", > + io_tlb_nslabs); > + } > + } > +} > + > void swiotlb_print_info(void) > { > unsigned long bytes = io_tlb_nslabs << IO_TLB_SHIFT; > -- > 2.17.1 >