From patchwork Wed Apr 13 13:36:21 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Hugo X-Patchwork-Id: 12812007 X-Patchwork-Delegate: lorenzo.pieralisi@arm.com 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 23AA6C433F5 for ; Wed, 13 Apr 2022 13:37:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235782AbiDMNjZ (ORCPT ); Wed, 13 Apr 2022 09:39:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47386 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231599AbiDMNjX (ORCPT ); Wed, 13 Apr 2022 09:39:23 -0400 Received: from alexa-out-sd-02.qualcomm.com (alexa-out-sd-02.qualcomm.com [199.106.114.39]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DEC0C5F240; Wed, 13 Apr 2022 06:37:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1649857021; x=1681393021; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=Vl6SQiy5vu9EZTWkVBhNnZBEyiT+stKz3fv32aZTWs0=; b=bxlBvB6nfaS2ovpRpaIxWlnyRshBBWJ/KzHkAUPjJYrxr55A6b8yhfX/ QFQDXuFBjkTGEqpSEgbC+j9t2q9GvUsjzX+1cvfMS9dmgluqxb9CvM5W0 PHiWu+Vi4zoZDgrthNFqyvaytqB3DDlf/5EPkTARUV5bxGXtu412oC4Qp I=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-02.qualcomm.com with ESMTP; 13 Apr 2022 06:37:01 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Apr 2022 06:37:01 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 13 Apr 2022 06:36:40 -0700 Received: from jhugo-lnx.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Wed, 13 Apr 2022 06:36:39 -0700 From: Jeffrey Hugo To: , , , , , , , , , CC: , , , , Jeffrey Hugo Subject: [PATCH v2] PCI: hv: Fix multi-MSI to allow more than one MSI vector Date: Wed, 13 Apr 2022 07:36:21 -0600 Message-ID: <1649856981-14649-1-git-send-email-quic_jhugo@quicinc.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 --- v2: -Fix grammatical mistake in added comment drivers/pci/controller/pci-hyperv.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index d270a204..1cbe24b 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -614,7 +614,16 @@ static void hv_set_msi_entry_from_desc(union hv_msi_entry *msi_entry, static int hv_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec, msi_alloc_info_t *info) { - return pci_msi_prepare(domain, dev, nvec, info); + int ret = pci_msi_prepare(domain, dev, nvec, info); + + /* + * By using the interrupt remapper in the hypervisor IOMMU, contiguous + * CPU vectors is not needed for multi-MSI + */ + if (info->type == X86_IRQ_ALLOC_TYPE_PCI_MSI) + info->flags &= ~X86_IRQ_ALLOC_CONTIGUOUS_VECTORS; + + return ret; } /**