From patchwork Mon Mar 30 16:50:39 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 1264143 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=nvidia.com header.i=@nvidia.com header.a=rsa-sha256 header.s=n1 header.b=PdT3FdBD; dkim-atps=neutral Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 48rfWh3Q2kz9sPk for ; Tue, 31 Mar 2020 04:26:24 +1100 (AEDT) Received: from localhost ([::1]:53722 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jIyB4-0004C2-Aw for incoming@patchwork.ozlabs.org; Mon, 30 Mar 2020 13:26:22 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:60660) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jIy9E-0000Md-IE for qemu-devel@nongnu.org; Mon, 30 Mar 2020 13:24:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1jIy9D-0002d0-Ek for qemu-devel@nongnu.org; Mon, 30 Mar 2020 13:24:28 -0400 Received: from hqnvemgate24.nvidia.com ([216.228.121.143]:1360) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1jIy9D-0002cM-8a for qemu-devel@nongnu.org; Mon, 30 Mar 2020 13:24:27 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate24.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 30 Mar 2020 10:22:50 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 30 Mar 2020 10:24:25 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 30 Mar 2020 10:24:25 -0700 Received: from HQMAIL105.nvidia.com (172.20.187.12) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 30 Mar 2020 17:24:25 +0000 Received: from kwankhede-dev.nvidia.com (10.124.1.5) by HQMAIL105.nvidia.com (172.20.187.12) with Microsoft SMTP Server (TLS) id 15.0.1473.3 via Frontend Transport; Mon, 30 Mar 2020 17:24:18 +0000 From: Kirti Wankhede To: , Subject: [PATCH v17 Kernel 2/7] vfio iommu: Remove atomicity of ref_count of pinned pages Date: Mon, 30 Mar 2020 22:20:39 +0530 Message-ID: <1585587044-2408-3-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1585587044-2408-1-git-send-email-kwankhede@nvidia.com> References: <1585587044-2408-1-git-send-email-kwankhede@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1585588970; bh=gmeXbRuItwuzRSa4wja8NeNbAoIY5SLtg52zFZ81snk=; h=X-PGP-Universal:From:To:CC:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:X-NVConfidentiality:MIME-Version: Content-Type; b=PdT3FdBDDzumHBMmfU1POMHCTDTmnm5Vv+fllHthZV4cJl5z7oouqOHw2kEFMIyuQ MUsWM2KPA6gmbK2NNcyc5EkxgqybYIEoJSQJ77Sxbo36+OgBmb+y5+LmxWfyuEe4R4 Cz7pqAaglF43rFbJ+STzkAQEjFqa+UU2EN7Ut3fIjQkzz740OifDRyC10YKNPSzhlF xpJPeY481uPF+5esHphuPCqo11zidwjsAtIcFtbGe62uZdVn2PQ8JIuPNpfiyHw2RS 8ozBbgiZhkANXsINsA8dKDa9CDAZr6hJRhpuuPNg6ubFzTz1OjxjbLPkvjihL9IDj0 i9lo0RT1/HWmw== X-detected-operating-system: by eggs.gnu.org: Windows 7 or 8 [fuzzy] X-Received-From: 216.228.121.143 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhengxiao.zx@Alibaba-inc.com, kevin.tian@intel.com, yi.l.liu@intel.com, yan.y.zhao@intel.com, kvm@vger.kernel.org, eskultet@redhat.com, ziye.yang@intel.com, qemu-devel@nongnu.org, cohuck@redhat.com, shuangtai.tst@alibaba-inc.com, dgilbert@redhat.com, zhi.a.wang@intel.com, mlevitsk@redhat.com, pasic@linux.ibm.com, aik@ozlabs.ru, Kirti Wankhede , eauger@redhat.com, felipe@nutanix.com, jonathan.davies@nutanix.com, changpeng.liu@intel.com, Ken.Xue@amd.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" vfio_pfn.ref_count is always updated while holding iommu->lock, using atomic variable is overkill. Signed-off-by: Kirti Wankhede Reviewed-by: Neo Jia Reviewed-by: Eric Auger Reviewed-by: Cornelia Huck --- drivers/vfio/vfio_iommu_type1.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index 9fdfae1cb17a..70aeab921d0f 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -112,7 +112,7 @@ struct vfio_pfn { struct rb_node node; dma_addr_t iova; /* Device address */ unsigned long pfn; /* Host pfn */ - atomic_t ref_count; + unsigned int ref_count; }; struct vfio_regions { @@ -233,7 +233,7 @@ static int vfio_add_to_pfn_list(struct vfio_dma *dma, dma_addr_t iova, vpfn->iova = iova; vpfn->pfn = pfn; - atomic_set(&vpfn->ref_count, 1); + vpfn->ref_count = 1; vfio_link_pfn(dma, vpfn); return 0; } @@ -251,7 +251,7 @@ static struct vfio_pfn *vfio_iova_get_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn = vfio_find_vpfn(dma, iova); if (vpfn) - atomic_inc(&vpfn->ref_count); + vpfn->ref_count++; return vpfn; } @@ -259,7 +259,8 @@ static int vfio_iova_put_vfio_pfn(struct vfio_dma *dma, struct vfio_pfn *vpfn) { int ret = 0; - if (atomic_dec_and_test(&vpfn->ref_count)) { + vpfn->ref_count--; + if (!vpfn->ref_count) { ret = put_pfn(vpfn->pfn, dma->prot); vfio_remove_from_pfn_list(dma, vpfn); }