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[34.140.232.180]) by smtp.gmail.com with ESMTPSA id bg16-20020a05600c3c9000b004149530aa97sm1014168wmb.10.2024.03.27.02.45.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Mar 2024 02:45:06 -0700 (PDT) Date: Wed, 27 Mar 2024 09:45:03 +0000 From: Mostafa Saleh To: Jason Gunthorpe Cc: iommu@lists.linux.dev, Joerg Roedel , linux-arm-kernel@lists.infradead.org, Robin Murphy , Will Deacon , Eric Auger , Jean-Philippe Brucker , Moritz Fischer , Michael Shavit , Nicolin Chen , patches@lists.linux.dev, Shameerali Kolothum Thodi Subject: Re: [PATCH v5 05/27] iommu/arm-smmu-v3: Make CD programming use arm_smmu_write_entry() Message-ID: References: <0-v5-9a37e0c884ce+31e3-smmuv3_newapi_p2_jgg@nvidia.com> <5-v5-9a37e0c884ce+31e3-smmuv3_newapi_p2_jgg@nvidia.com> <20240326183055.GL6245@nvidia.com> <20240326222758.GB946323@nvidia.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240326222758.GB946323@nvidia.com> On Tue, Mar 26, 2024 at 07:27:58PM -0300, Jason Gunthorpe wrote: > On Tue, Mar 26, 2024 at 07:12:53PM +0000, Mostafa Saleh wrote: > > On Tue, Mar 26, 2024 at 03:30:55PM -0300, Jason Gunthorpe wrote: > > > On Sat, Mar 23, 2024 at 01:02:15PM +0000, Mostafa Saleh wrote: > > > > > +static void arm_smmu_get_cd_used(const __le64 *ent, __le64 *used_bits) > > > > > +{ > > > > > + used_bits[0] = cpu_to_le64(CTXDESC_CD_0_V); > > > > > + if (!(ent[0] & cpu_to_le64(CTXDESC_CD_0_V))) > > > > > + return; > > > > > + memset(used_bits, 0xFF, sizeof(struct arm_smmu_cd)); > > > > > > > > This is a slightly different approach than what the driver does for STEs, > > > > where it explicitly sets the used bits. Is there a reason for that? > > > > > > It is just more compact this way > > > > IMHO, it seems too much to have this mechanism for CDs for just one > > SVA case, but I'll need to go through the whole seires first to make > > sure I am not missing anything. > > It is pretty ugly if you try to do it that way. You still need to > create some ops because the entry_set should be re-used (I mean I > guess you could copy it as well). Then you have to open code the > logic. And then the EPD0 path is somewhat fragile. Something sort of > like this: > > void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid, > struct arm_smmu_cd *cdptr, > const struct arm_smmu_cd *target) > { > bool target_valid = target->data[0] & cpu_to_le64(CTXDESC_CD_0_V); > bool cur_valid = cdptr->data[0] & cpu_to_le64(CTXDESC_CD_0_V); > struct arm_smmu_cd_writer cd_writer = { > .writer = { > .ops = &arm_smmu_cd_writer_ops, > .master = master, > }, > .ssid = ssid, > }; > > if (ssid != IOMMU_NO_PASID && cur_valid != target_valid) { > if (cur_valid) > master->cd_table.used_ssids--; > else > master->cd_table.used_ssids++; > } > > /* Force a V=0/V=1 update*/ > __le64 update = target[0] & ~cpu_to_le64(CTXDESC_CD_0_V); > entry_set(&cd_writer.writer, cdptr->data, &update, 0, 1); > entry_set(&cd_writer.writer, cdptr->data, target->data, 1, NUM_ENTRY_QWORDS - 1); > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, 1); > } > > void arm_smmu_write_cd_entry_epd0(struct arm_smmu_master *master, int ssid, > struct arm_smmu_cd *cdptr, > const struct arm_smmu_cd *target) > { > struct arm_smmu_cd_writer cd_writer = { > .writer = { > .ops = &arm_smmu_cd_writer_ops, > .master = master, > }, > .ssid = ssid, > }; > > /* > * Target must the EPD0 = 1 version of the existing CD entry, caller > * must enforce it. Assume used_ssids doesn't need updating > * for this reason. > */ > /* Update EPD0 */ > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, 1); > /* Update everthing else */ > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, NUM_ENTRY_QWORDS - 1); > } > > IMOH, at this point it is saner to have just implemented the used > function and use the mechanism robustly. Less special cases, less > fragility, less duplication. > But that adds extra cost of adding ops, indirection, modifying STE code..., for a case that is not common, so I think special casing it is actually better for readability and maintainability. But again, I need to finish going through the series to get the full context. Thanks, Mostafa 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 4B415C54E67 for ; Wed, 27 Mar 2024 09:45:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=CI7Z+6U9ZhfWjyZsULShfBIJ/rYibleqC/ZMWYHIneM=; b=qHsYDS7bFoa9ir 5Yil5H4KR+AjQQ8h0hnY6pfwsNX5sTID8qTZ2+FWzwpMnAsFktlGXYATX3xiMayyTUC9tXKeGNJlt k9z18+52RjezeXEf6lTrSKY9UzJaupVm5Cs5LjZwQKU56+ChwWb80TGKDNmuRs2gtpWUhabbWwvmI bb1vE4bgGlJOWjjzzNiHxg7ZQhwjtUNLulsLdhLHAAIdspKG3cxuZ+C43hOUcOGS9FzLjxpgpNWQV KEYVvrQAP+oEIST1sIqLwZx1YR5tOkKl3pB+85wCfOVM4yNCbNeNW3DWNbTyHKZMtG5KmbpN/U+GM wjzGU5e6kZ+nIk7rAQ7g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.97.1 #2 (Red Hat Linux)) id 1rpPqL-00000008H7T-3nai; Wed, 27 Mar 2024 09:45:13 +0000 Received: from mail-wm1-x32a.google.com ([2a00:1450:4864:20::32a]) by bombadil.infradead.org with esmtps (Exim 4.97.1 #2 (Red Hat Linux)) id 1rpPqH-00000008H5R-2CPx for linux-arm-kernel@lists.infradead.org; Wed, 27 Mar 2024 09:45:10 +0000 Received: by mail-wm1-x32a.google.com with SMTP id 5b1f17b1804b1-4148c09ec6bso49595e9.1 for ; Wed, 27 Mar 2024 02:45:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1711532707; x=1712137507; 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=OryA0DL61czc89Wzep0XB0rzJHnSp9bK/m8Spm5OPdc=; b=UfXf9UrXrkb2FwmiFtNIRqsUwR4wcVkP/TLGD2ARvNQZD0mWI0pD7KH9jUY+ARK+4X HPpCBJi9jDtaA6FLoaq1cc64BjtCXx5XOj7aYBtVCOWRoaNNkKMb8ZDYE1GmaXbwHT0o t+FtL74PrReKzwKv/V28DG4BmC/Z9heJTEwSWuVzfMHTxcLvfXNKgITjcAbqiYrAaTkS P6ZSwRwas1NNWVMIBsT7O/u0ABDl1+R+9ItHm8+ku96gtKxIxKRHwnuzTtKbnO8sapk2 qeIbZS9f/vtuLekn6StYthLpBeJrAsfIMhB04BqRw6T3OpuFPxPwZXg6UZ+Z8POKJ14P 6vhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1711532707; x=1712137507; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=OryA0DL61czc89Wzep0XB0rzJHnSp9bK/m8Spm5OPdc=; b=KIhTUkFC609ZXrNcVnQsWcNRPzsfSWE8aGkUWxTGV1ox+TV4z33JPLVbbHn1DNtxeU h7JKXCgIttyqNG0eIEzjBxYZ7oPNpc+GvNAcEqAUQHyQ+Vs1riH28FC9+Cjsf67LWsP0 eb4hQMDHBvu672P12sCvnxUwQ5lglDehfArdZYh2LDNu4yXTw2pR78i4o8ctrkPvDbiq kVh8AZvzvMCKrVJ4vIDMNd0wxUMckdWJwmhW2VAc2ap0T3CI8KIyxfbI4t8hensk07CE 2KcxkES9LpIK/UF1qYbdSiFkFbNh66dFf+aFGkExcMlrKC4mQbGCMdNcaB3H1bpd38VL mDEQ== X-Forwarded-Encrypted: i=1; AJvYcCXmKdFu0pZ4Oj8xK+qIoda0J6VvNWLTfi6c9XjpsizSeLCR7cfqk3I+HUtPFi/vOKKVtvA7/37lynHbo3dLRf8km6Vpt2HJE8iwufdKrfLDtgplKgs= X-Gm-Message-State: AOJu0YywpFf1eJuQx18UBNiInjR+vZfPcBfk15fAYSolbLDpHMyscpJY w1Nhyl+7QNRjVKe2cMPO0TBwm+bfnp5XZPexHJ1jL6KaFNk6muDoObL1JLzEng== X-Google-Smtp-Source: AGHT+IHGxC+UcFmgO1pgvObazWB/Eg7/jxwHvz1SR3oU22gwkCQVZujrI3wM0Nhp4dZpcAGjG2YAYg== X-Received: by 2002:a05:600c:35c8:b0:414:1400:a776 with SMTP id r8-20020a05600c35c800b004141400a776mr71704wmq.5.1711532707236; Wed, 27 Mar 2024 02:45:07 -0700 (PDT) Received: from google.com (180.232.140.34.bc.googleusercontent.com. [34.140.232.180]) by smtp.gmail.com with ESMTPSA id bg16-20020a05600c3c9000b004149530aa97sm1014168wmb.10.2024.03.27.02.45.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 27 Mar 2024 02:45:06 -0700 (PDT) Date: Wed, 27 Mar 2024 09:45:03 +0000 From: Mostafa Saleh To: Jason Gunthorpe Cc: iommu@lists.linux.dev, Joerg Roedel , linux-arm-kernel@lists.infradead.org, Robin Murphy , Will Deacon , Eric Auger , Jean-Philippe Brucker , Moritz Fischer , Michael Shavit , Nicolin Chen , patches@lists.linux.dev, Shameerali Kolothum Thodi Subject: Re: [PATCH v5 05/27] iommu/arm-smmu-v3: Make CD programming use arm_smmu_write_entry() Message-ID: References: <0-v5-9a37e0c884ce+31e3-smmuv3_newapi_p2_jgg@nvidia.com> <5-v5-9a37e0c884ce+31e3-smmuv3_newapi_p2_jgg@nvidia.com> <20240326183055.GL6245@nvidia.com> <20240326222758.GB946323@nvidia.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20240326222758.GB946323@nvidia.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240327_024509_623431_EB6C95B9 X-CRM114-Status: GOOD ( 28.87 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Mar 26, 2024 at 07:27:58PM -0300, Jason Gunthorpe wrote: > On Tue, Mar 26, 2024 at 07:12:53PM +0000, Mostafa Saleh wrote: > > On Tue, Mar 26, 2024 at 03:30:55PM -0300, Jason Gunthorpe wrote: > > > On Sat, Mar 23, 2024 at 01:02:15PM +0000, Mostafa Saleh wrote: > > > > > +static void arm_smmu_get_cd_used(const __le64 *ent, __le64 *used_bits) > > > > > +{ > > > > > + used_bits[0] = cpu_to_le64(CTXDESC_CD_0_V); > > > > > + if (!(ent[0] & cpu_to_le64(CTXDESC_CD_0_V))) > > > > > + return; > > > > > + memset(used_bits, 0xFF, sizeof(struct arm_smmu_cd)); > > > > > > > > This is a slightly different approach than what the driver does for STEs, > > > > where it explicitly sets the used bits. Is there a reason for that? > > > > > > It is just more compact this way > > > > IMHO, it seems too much to have this mechanism for CDs for just one > > SVA case, but I'll need to go through the whole seires first to make > > sure I am not missing anything. > > It is pretty ugly if you try to do it that way. You still need to > create some ops because the entry_set should be re-used (I mean I > guess you could copy it as well). Then you have to open code the > logic. And then the EPD0 path is somewhat fragile. Something sort of > like this: > > void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid, > struct arm_smmu_cd *cdptr, > const struct arm_smmu_cd *target) > { > bool target_valid = target->data[0] & cpu_to_le64(CTXDESC_CD_0_V); > bool cur_valid = cdptr->data[0] & cpu_to_le64(CTXDESC_CD_0_V); > struct arm_smmu_cd_writer cd_writer = { > .writer = { > .ops = &arm_smmu_cd_writer_ops, > .master = master, > }, > .ssid = ssid, > }; > > if (ssid != IOMMU_NO_PASID && cur_valid != target_valid) { > if (cur_valid) > master->cd_table.used_ssids--; > else > master->cd_table.used_ssids++; > } > > /* Force a V=0/V=1 update*/ > __le64 update = target[0] & ~cpu_to_le64(CTXDESC_CD_0_V); > entry_set(&cd_writer.writer, cdptr->data, &update, 0, 1); > entry_set(&cd_writer.writer, cdptr->data, target->data, 1, NUM_ENTRY_QWORDS - 1); > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, 1); > } > > void arm_smmu_write_cd_entry_epd0(struct arm_smmu_master *master, int ssid, > struct arm_smmu_cd *cdptr, > const struct arm_smmu_cd *target) > { > struct arm_smmu_cd_writer cd_writer = { > .writer = { > .ops = &arm_smmu_cd_writer_ops, > .master = master, > }, > .ssid = ssid, > }; > > /* > * Target must the EPD0 = 1 version of the existing CD entry, caller > * must enforce it. Assume used_ssids doesn't need updating > * for this reason. > */ > /* Update EPD0 */ > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, 1); > /* Update everthing else */ > entry_set(&cd_writer.writer, cdptr->data, target->data, 0, NUM_ENTRY_QWORDS - 1); > } > > IMOH, at this point it is saner to have just implemented the used > function and use the mechanism robustly. Less special cases, less > fragility, less duplication. > But that adds extra cost of adding ops, indirection, modifying STE code..., for a case that is not common, so I think special casing it is actually better for readability and maintainability. But again, I need to finish going through the series to get the full context. Thanks, Mostafa _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel