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 Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 66396C433FE for ; Wed, 2 Mar 2022 08:15:14 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 0244C40245; Wed, 2 Mar 2022 08:15:14 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 6Vr50i3LB2Yw; Wed, 2 Mar 2022 08:15:13 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp4.osuosl.org (Postfix) with ESMTPS id B9AED40215; Wed, 2 Mar 2022 08:15:12 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9834AC0082; Wed, 2 Mar 2022 08:15:12 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 98EF8C000B for ; Wed, 2 Mar 2022 08:15:10 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 7107D40396 for ; Wed, 2 Mar 2022 08:15:10 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id FWDL66vPRuFP for ; Wed, 2 Mar 2022 08:15:09 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp2.osuosl.org (Postfix) with ESMTPS id 8ECB540136 for ; Wed, 2 Mar 2022 08:15:09 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 527A368BEB; Wed, 2 Mar 2022 09:15:01 +0100 (CET) Date: Wed, 2 Mar 2022 09:15:00 +0100 From: Christoph Hellwig To: Stefano Stabellini Subject: Re: [PATCH 11/12] swiotlb: merge swiotlb-xen initialization into swiotlb Message-ID: <20220302081500.GB23075@lst.de> References: <20220301105311.885699-1-hch@lst.de> <20220301105311.885699-12-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: linux-hyperv@vger.kernel.org, x86@kernel.org, linux-ia64@vger.kernel.org, linux-pci@vger.kernel.org, linux-riscv@lists.infradead.org, Christoph Hellwig , linux-s390@vger.kernel.org, Konrad Rzeszutek Wilk , tboot-devel@lists.sourceforge.net, xen-devel@lists.xenproject.org, David Woodhouse , Tom Lendacky , Anshuman Khandual , Boris Ostrovsky , linux-arm-kernel@lists.infradead.org, Juergen Gross , Robin Murphy , linux-mips@vger.kernel.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Tue, Mar 01, 2022 at 06:55:47PM -0800, Stefano Stabellini wrote: > Unrelated to this specific patch series: now that I think about it, if > io_tlb_default_mem.nslabs is already allocated by the time xen_mm_init > is called, wouldn't we potentially have an issue with the GFP flags used > for the earlier allocation (e.g. GFP_DMA32 not used)? Maybe something > for another day. swiotlb_init allocates low memory from meblock, which is roughly equivalent to GFP_DMA allocations, so we'll be fine. > > @@ -143,10 +141,15 @@ static int __init xen_mm_init(void) > > if (!xen_swiotlb_detect()) > > return 0; > > > > - rc = xen_swiotlb_init(); > > /* we can work with the default swiotlb */ > > - if (rc < 0 && rc != -EEXIST) > > - return rc; > > + if (!io_tlb_default_mem.nslabs) { > > + if (!xen_initial_domain()) > > + return -EINVAL; > > I don't think we need this xen_initial_domain() check. It is all > already sorted out by the xen_swiotlb_detect() check above. Is it? static inline int xen_swiotlb_detect(void) { if (!xen_domain()) return 0; if (xen_feature(XENFEAT_direct_mapped)) return 1; /* legacy case */ if (!xen_feature(XENFEAT_not_direct_mapped) && xen_initial_domain()) return 1; return 0; } I think I'd keep it as-is for now, as my planned next step would be to fold xen-swiotlb into swiotlb entirely. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu