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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 4ACCBCD342F for ; Fri, 8 May 2026 16:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=U4Q1eWfw8uO06O3f0d5ochR+epxjNtDwxTshSdkC+mc=; b=LT3+SkijD0tUN+PjpTOph9COfx 1rAb9bTxFXPV1no5loYhEu3tLr+kaoNXkMcHc3n4Si7FU52SYkgBF0F/CutFwJPvbNodt9vO66klG tmymcHQX7yQtBaF4zwnPxPlAS71iPxZuLA27Vzj1YaCGAKzi9SapH8KwZIwa7mPcNtWG6E8NQ6xpg R6VXyCE1r7nzghd26YveQMfT61Eh3ai3HsFpD6OL6e7VXUstszB1OHh23EoLS58jby2MP76jrWTm2 2/H6E1ng9yo3G9/Z7A0Y22TlOhaM8qrgD+Ih3kD5Cm6xeCILIDMQqFiLcabvcMRLtUtwUmkMC0hCh x8LEe2Vw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wLOX7-000000073UD-33dg; Fri, 08 May 2026 16:58:37 +0000 Received: from mail-pl1-x634.google.com ([2607:f8b0:4864:20::634]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wLOX4-000000073TN-0wIk for linux-arm-kernel@lists.infradead.org; Fri, 08 May 2026 16:58:36 +0000 Received: by mail-pl1-x634.google.com with SMTP id d9443c01a7336-2ba180a022dso114355ad.1 for ; Fri, 08 May 2026 09:58:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1778259513; x=1778864313; darn=lists.infradead.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=U4Q1eWfw8uO06O3f0d5ochR+epxjNtDwxTshSdkC+mc=; b=djFCotCqwhFxMCm04c3GEiRZpSH6e3So/K2mejT7avTxs9HYiYHfhhg5Sjvvchsgux 7QbIxTrUyA66eTIQyBrltjqkder1KPid5RTwA9IeqodZvDd4h+rEIT7tcIvckzDdodzI l69F2bQSltcNyenvwFwNhKAHFqu34o08N5C6swGRq/lijXOS/J+PMsN+uFfzVYKx/nxT oMwPb55eedbYHITeCbWDyk9cziSauRep64iBUsRgWgGj0PcwIlwnhGPg8TOB+rR1zRmq znTExsH1nV84pA3xp0cPIx7qkrTrW/wpXeNtKOKGLdwidPJziNYj/xaaN2o9nw6YwR/8 urDg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1778259513; x=1778864313; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-gg:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=U4Q1eWfw8uO06O3f0d5ochR+epxjNtDwxTshSdkC+mc=; b=Q+RPUzK7/AeEPn4mdeoLgV/LQHGrdliii7faf80eSTRZqjVKOmCYi57Tlm7qVSay+o 26F2/relfOOLDsc2a0UH/6mgnRX2Cqdbk2zNgNfwgO5nKiqyV1HUZdW/0XD3IiwOYzWq ER/428QKmu8pAF/mzxPRK3MQPioWvPrftXNES93kHfvyq9Mjkq07W4CdHn0qDZdb10Xk 4/YbtGminQo3+uE7nL5IIXT4F/LRgdbR8wUuyZ6RSJy7Slwl4DvDIxl77ZAOYDltzxp2 i/zs1o0WxBScyrs9BYgxPj5fiLhcF2ozx777sI8mA3YaLDQGU+7Fwn6qY+52OBsJspiq ha0w== X-Forwarded-Encrypted: i=1; AFNElJ+zltr1FKrUlRKrZuMbEAFHUObdOTK7Bzx/8/3PxK6LS4A084UVRbyoRc5pgaxqID78DBuLvIwKTnWsSomK0Tyl@lists.infradead.org X-Gm-Message-State: AOJu0YyPmZART7Qu+NplPEFShYa1DNkPk0H78SLEL8y8Wo0LEdJx1Cb4 TiC1Ufl27BYZMJQJ4dsSB6SMGe0xYN/kkzzCUc5+l9u/gpJMKbi6AP03QXoiYJAbIw== X-Gm-Gg: Acq92OHYZ/mYx84hdPd7x3aRRTfI3eqAZoxKNm8MXKP7xszTbgRZmmBcFgBJTWUvdnD vV1J096mYRI54wa/1w2HZWBXUX0rgUI/rbPtXy6Xn5xHgGaT3WtSe3tBKMetQvjMfoHANtdHG+W 8e9n2LlZ3HeezgMwMUy1YU3ArHJSG8RDqhsG65qLq+Oqqpx3YNzqlVS0cRn0ooa272cTDHz/gnO 63Sv+p+tknIisIvXFEfcXqGxnDCCZDQjwckCXmJdsTRRTtPJrBEGBpuUkUsQ5FxOPWvke2h2Orn 1sjuxRvh+bmMbC9IunX1CyIVCApAuLZrJ42G5SNQonwPk0qmAhi3WP0uef/RbeDHw7tkpnO7+Lu Oq7NArRIEfE0MrSlFHgWZCsD6ok2+8HNo8wiGHA1L3O5bIgK49zkv25p/zwmhN5FVtLWsrSRJvO 11Li14Q5CJIHcA+y9uVj5t9M0mN9mso+RW+rXvPQ/4BvWJf0j3Gjei8tadNGkiuYBH3BMy X-Received: by 2002:a17:902:da87:b0:2ba:f71:57a8 with SMTP id d9443c01a7336-2bae9e663eamr3999045ad.10.1778259512872; Fri, 08 May 2026 09:58:32 -0700 (PDT) Received: from google.com (44.234.124.34.bc.googleusercontent.com. [34.124.234.44]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2baf1d2700dsm29924885ad.2.2026.05.08.09.58.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 May 2026 09:58:31 -0700 (PDT) Date: Fri, 8 May 2026 16:58:25 +0000 From: Pranjal Shrivastava To: Jason Gunthorpe Cc: iommu@lists.linux.dev, Jonathan Hunter , Joerg Roedel , linux-arm-kernel@lists.infradead.org, linux-tegra@vger.kernel.org, Robin Murphy , Thierry Reding , Krishna Reddy , Will Deacon , David Matlack , Pasha Tatashin , patches@lists.linux.dev, Samiullah Khawaja , Mostafa Saleh Subject: Re: [PATCH 2/9] iommu/arm-smmu-v3: Use the HW arm_smmu_cmd in cmdq selection functions Message-ID: References: <0-v1-b7dc0a0d4aa0+3723d-smmu_no_cmdq_ent_jgg@nvidia.com> <2-v1-b7dc0a0d4aa0+3723d-smmu_no_cmdq_ent_jgg@nvidia.com> <20260508155432.GE9254@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260508155432.GE9254@nvidia.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260508_095834_270552_D6CDFF51 X-CRM114-Status: GOOD ( 20.62 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, May 08, 2026 at 12:54:32PM -0300, Jason Gunthorpe wrote: > On Fri, May 08, 2026 at 07:47:45AM +0000, Pranjal Shrivastava wrote: > > On Fri, May 01, 2026 at 11:29:11AM -0300, Jason Gunthorpe wrote: > > > Start removing the use of struct arm_smmu_cmdq_ent, starting at the > > > lower levels of the call chain. Change the functions that determine what > > > cmdq to issue the batch to into using struct arm_smmu_cmd directly. > > > > > > Signed-off-by: Jason Gunthorpe > > > --- > > > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 47 ++++++++++++------- > > > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 8 ++-- > > > .../iommu/arm/arm-smmu-v3/tegra241-cmdqv.c | 8 ++-- > > > 3 files changed, 38 insertions(+), 25 deletions(-) > > > > [...] > > > > > index = cmds->num * CMDQ_ENT_DWORDS; > > > - if (unlikely(arm_smmu_cmdq_build_cmd(&cmds->cmds[index], cmd))) { > > > - dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x\n", > > > - cmd->opcode); > > > - return; > > > - } > > > - > > > + memcpy(&cmds->cmds[index], cmd.data, sizeof(cmd.data)); > > > cmds->num++; > > > } > > > > The memcpy is a temporary step and goes way in Patch 4. > > To be clear patch 4 still has the memcpy: > > - index = cmds->num * CMDQ_ENT_DWORDS; > - memcpy(&cmds->cmds[index], cmd.data, sizeof(cmd.data)); > - cmds->num++; > + cmds->cmds[cmds->num++] = cmd; > ^^^^^^^^^^^ > > The compiler just builds it. > > The flow evolution is: > > Now: > struct arm_smmu_cmdq_ent (stack) -> arm_smmu_cmdq_build_cmd (batch) -> memcpy (queue) > Here: > struct arm_smmu_cmdq_ent (stack) -> arm_smmu_cmdq_build_cmd (stack) -> memcpy (batch) -> memcpy (queue) > Done: > struct arm_smmu_cmd (stack) -> memcpy (batch) -> memcpy (queue) > > So the net result is the same before/after this series, we just carry > an extra stack copy till the last patch. Right that makes sense. N Thanks, Praan