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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 331E4C433FE for ; Mon, 25 Apr 2022 15:33:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240947AbiDYPgw (ORCPT ); Mon, 25 Apr 2022 11:36:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230098AbiDYPgv (ORCPT ); Mon, 25 Apr 2022 11:36:51 -0400 Received: from mail-wr1-f41.google.com (mail-wr1-f41.google.com [209.85.221.41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B299243380; Mon, 25 Apr 2022 08:33:47 -0700 (PDT) Received: by mail-wr1-f41.google.com with SMTP id t6so17992354wra.4; Mon, 25 Apr 2022 08:33:47 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=+OQDcwFgZu/P9vx+VQN8SgQh5Ecb0LyT6OAUuz0M6w4=; b=4ejo69psq47xfRafXKT+ybqY29uqxJ4p476g4qUM+YXu2lYqbq/Gs5co6aFO/lcxd/ qOU3HFYTMaua9Mnh9Lb4rkg6XModqPwp4vN74kfwi144vnzqc/53UmFIKQGMgPAcxNyQ TreDyzBofHA5PYepMmGRCwHythQMlH1TUgsipqUkyHwku5JMZIWs3PJjJCCCpPw9yMrl /Q0rlKYU9oRSRviI5tnP+xcojBuT2bJOUu5qiJEQL8CanvAw20jrI/1JN9IM8Dpr4BTj mT93VJnssFyoig4H4/pk0CZl5Fkt7NKPl3hV0AFnjsHGRtvFSZ1TBw3kx7YeVKbr7BBh 1eOg== X-Gm-Message-State: AOAM530FNG2b0VrX5crGfTH4vor7cjshMYkGqAFgXndbdvcP5RXkUwJU c8Am8HTM+Rf8dMC9Gm3QcXw= X-Google-Smtp-Source: ABdhPJy33w5nmyRINYX7dcYjstdfIFot4qy6wHNJDM5nuqJqkpo7RIQBW60m1pDN7gGh2dmpAaArFw== X-Received: by 2002:adf:f64b:0:b0:20a:c685:89ee with SMTP id x11-20020adff64b000000b0020ac68589eemr13797875wrp.366.1650900826224; Mon, 25 Apr 2022 08:33:46 -0700 (PDT) Received: from liuwe-devbox-debian-v2 ([51.145.34.42]) by smtp.gmail.com with ESMTPSA id i27-20020a1c541b000000b003928e866d32sm12212227wmb.37.2022.04.25.08.33.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Apr 2022 08:33:45 -0700 (PDT) Date: Mon, 25 Apr 2022 15:33:44 +0000 From: Wei Liu To: Jeffrey Hugo Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, lorenzo.pieralisi@arm.com, robh@kernel.org, kw@linux.com, bhelgaas@google.com, jakeo@microsoft.com, bjorn.andersson@linaro.org, linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] PCI: hv: Fix multi-MSI to allow more than one MSI vector Message-ID: <20220425153344.lgo3kdnrbef75jcq@liuwe-devbox-debian-v2> References: <1649856981-14649-1-git-send-email-quic_jhugo@quicinc.com> <2100eed4-8081-6070-beaf-7c6ba65ad9be@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2100eed4-8081-6070-beaf-7c6ba65ad9be@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Wed, Apr 20, 2022 at 08:13:22AM -0600, Jeffrey Hugo wrote: > On 4/13/2022 7:36 AM, Jeffrey Hugo wrote: > > If the allocation of multiple MSI vectors for multi-MSI fails in the core > > PCI framework, the framework will retry the allocation as a single MSI > > vector, assuming that meets the min_vecs specified by the requesting > > driver. > > > > Hyper-V advertises that multi-MSI is supported, but reuses the VECTOR > > domain to implement that for x86. The VECTOR domain does not support > > multi-MSI, so the alloc will always fail and fallback to a single MSI > > allocation. > > > > In short, Hyper-V advertises a capability it does not implement. > > > > Hyper-V can support multi-MSI because it coordinates with the hypervisor > > to map the MSIs in the IOMMU's interrupt remapper, which is something the > > VECTOR domain does not have. Therefore the fix is simple - copy what the > > x86 IOMMU drivers (AMD/Intel-IR) do by removing > > X86_IRQ_ALLOC_CONTIGUOUS_VECTORS after calling the VECTOR domain's > > pci_msi_prepare(). > > > > Fixes: 4daace0d8ce8 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs") > > Signed-off-by: Jeffrey Hugo > > Reviewed-by: Dexuan Cui > > --- > > Ping? > > I don't see this in -next, nor have I seen any replies. It is possible I > have missed some kind of update, but currently I'm wondering if this change > is progressing or not. If there is some kind of process used in this area, > I'm not familiar with it, so I would appreciate an introduction. I expect the PCI maintainers to pick this up. If I don't see this picked up in this week I will apply it to hyperv-next. Thanks, Wei. > > Thanks > > -Jeff