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 X-Spam-Level: X-Spam-Status: No, score=-12.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 82964C433E7 for ; Thu, 15 Oct 2020 14:28:28 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EADE922255 for ; Thu, 15 Oct 2020 14:28:27 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="rTeQmRwa" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EADE922255 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=ElqcGNh5WlpHvMSq0CsABHygQg+AxfMulF5q/HXtqh0=; b=rTeQmRwaJ0t45jGL25O2XTFYu 7cz33jDVEOgm3nEU1zDvUsS6U3efszvXGZGBHl1EkYOc++tw3LGH5NfAl2b3yyNd3apcgtXUTIfwM LzcZu+cFxOD+21NtFS5GujMhMsVqoXvJ0wpARB8MwNlG2WtLqGCq6y4hw2z6bmU4DQk/9zQq4xAVv bzHAWb+0Vv0qNod6wDA/VEwgWxV1MPquArpVCBmVWKbgfnUaEKDL+e6f2fBRLJ1jhCzJtSsTKtR3Q 0c1MjtpUF/RVbr8sZscSftgq4M+BZoU4hfDCg7zktOn/W7M6Apas093mQr6lbCMpjOzoJvE18kbLV lDGhI7rSw==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT4DM-0003mE-LZ; Thu, 15 Oct 2020 14:26:44 +0000 Received: from szxga05-in.huawei.com ([45.249.212.191] helo=huawei.com) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT4DI-0003kW-A7; Thu, 15 Oct 2020 14:26:42 +0000 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id B13A6E19BE4EE9CE4DA9; Thu, 15 Oct 2020 22:26:24 +0800 (CST) Received: from [10.174.179.182] (10.174.179.182) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.487.0; Thu, 15 Oct 2020 22:26:19 +0800 Subject: Re: [PATCH v3 7/8] arm64: mm: Set ZONE_DMA size based on early IORT scan To: Nicolas Saenz Julienne , , , , , , Lorenzo Pieralisi , Sudeep Holla References: <20201014191211.27029-1-nsaenzjulienne@suse.de> <20201014191211.27029-8-nsaenzjulienne@suse.de> From: Hanjun Guo Message-ID: <1a3df60a-4568-cb72-db62-36127d0ffb7e@huawei.com> Date: Thu, 15 Oct 2020 22:26:18 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20201014191211.27029-8-nsaenzjulienne@suse.de> Content-Language: en-GB X-Originating-IP: [10.174.179.182] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201015_102642_062883_D1E0A0AE X-CRM114-Status: GOOD ( 34.22 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, Anshuman Khandual , Will Deacon , "Rafael J. Wysocki" , jeremy.linton@arm.com, linux-acpi@vger.kernel.org, iommu@lists.linux-foundation.org, linux-rpi-kernel@lists.infradead.org, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, Len Brown Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020/10/15 3:12, Nicolas Saenz Julienne wrote: > From: Ard Biesheuvel > > We recently introduced a 1 GB sized ZONE_DMA to cater for platforms > incorporating masters that can address less than 32 bits of DMA, in > particular the Raspberry Pi 4, which has 4 or 8 GB of DRAM, but has > peripherals that can only address up to 1 GB (and its PCIe host > bridge can only access the bottom 3 GB) > > Instructing the DMA layer about these limitations is straight-forward, > even though we had to fix some issues regarding memory limits set in > the IORT for named components, and regarding the handling of ACPI _DMA > methods. However, the DMA layer also needs to be able to allocate > memory that is guaranteed to meet those DMA constraints, for bounce > buffering as well as allocating the backing for consistent mappings. > > This is why the 1 GB ZONE_DMA was introduced recently. Unfortunately, > it turns out the having a 1 GB ZONE_DMA as well as a ZONE_DMA32 causes > problems with kdump, and potentially in other places where allocations > cannot cross zone boundaries. Therefore, we should avoid having two > separate DMA zones when possible. > > So let's do an early scan of the IORT, and only create the ZONE_DMA > if we encounter any devices that need it. This puts the burden on > the firmware to describe such limitations in the IORT, which may be > redundant (and less precise) if _DMA methods are also being provided. > However, it should be noted that this situation is highly unusual for > arm64 ACPI machines. Also, the DMA subsystem still gives precedence to > the _DMA method if implemented, and so we will not lose the ability to > perform streaming DMA outside the ZONE_DMA if the _DMA method permits > it. Sorry, I'm still a little bit confused. With this patch, if we have a device which set the right _DMA method (DMA size >= 32), but with the wrong DMA size in IORT, we still have the ZONE_DMA created which is actually not needed? > > Cc: Jeremy Linton > Cc: Lorenzo Pieralisi > Cc: Nicolas Saenz Julienne > Cc: Rob Herring > Cc: Christoph Hellwig > Cc: Robin Murphy > Cc: Hanjun Guo > Cc: Sudeep Holla > Cc: Anshuman Khandual > Signed-off-by: Ard Biesheuvel > [nsaenz: Rebased, removed documentation change, warnings and add > declaration in acpi_iort.h] > Signed-off-by: Nicolas Saenz Julienne > --- > arch/arm64/mm/init.c | 6 +++++ > drivers/acpi/arm64/iort.c | 51 +++++++++++++++++++++++++++++++++++++++ > include/linux/acpi_iort.h | 4 +++ > 3 files changed, 61 insertions(+) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 97b0d2768349..f321761eedb2 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -29,6 +29,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -196,6 +197,11 @@ static void __init zone_sizes_init(unsigned long min, unsigned long max) > #ifdef CONFIG_ZONE_DMA > zone_dma_bits = min(zone_dma_bits, > (unsigned int)ilog2(of_dma_get_max_cpu_address(NULL))); > + > + if (IS_ENABLED(CONFIG_ACPI)) > + zone_dma_bits = min(zone_dma_bits, > + acpi_iort_get_zone_dma_size()); > + > arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); > max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); > #endif > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c > index 9929ff50c0c0..8f530bf3c03b 100644 > --- a/drivers/acpi/arm64/iort.c > +++ b/drivers/acpi/arm64/iort.c > @@ -1718,3 +1718,54 @@ void __init acpi_iort_init(void) > > iort_init_platform_devices(); > } > + > +#ifdef CONFIG_ZONE_DMA > +/* > + * Check the IORT whether any devices exist whose DMA mask is < 32 bits. > + * If so, return the smallest value encountered, or 32 otherwise. > + */ > +unsigned int __init acpi_iort_get_zone_dma_size(void) > +{ > + struct acpi_table_iort *iort; > + struct acpi_iort_node *node, *end; > + acpi_status status; > + u8 limit = 32; > + int i; > + > + if (acpi_disabled) > + return limit; > + > + status = acpi_get_table(ACPI_SIG_IORT, 0, > + (struct acpi_table_header **)&iort); > + if (ACPI_FAILURE(status)) > + return limit; > + > + node = ACPI_ADD_PTR(struct acpi_iort_node, iort, iort->node_offset); > + end = ACPI_ADD_PTR(struct acpi_iort_node, iort, iort->header.length); > + > + for (i = 0; i < iort->node_count; i++) { > + if (node >= end) > + break; > + > + switch (node->type) { > + struct acpi_iort_named_component *ncomp; > + struct acpi_iort_root_complex *rc; > + > + case ACPI_IORT_NODE_NAMED_COMPONENT: > + ncomp = (struct acpi_iort_named_component *)node->node_data; > + if (ncomp->memory_address_limit) > + limit = min(limit, ncomp->memory_address_limit); > + break; > + > + case ACPI_IORT_NODE_PCI_ROOT_COMPLEX: > + rc = (struct acpi_iort_root_complex *)node->node_data; > + if (rc->memory_address_limit) > + limit = min(limit, rc->memory_address_limit); There is no "Memory address size limit" field in revision 0 table, so as Lorenzo reminded, please add a revision check here. Thanks Hanjun > + break; > + } > + node = ACPI_ADD_PTR(struct acpi_iort_node, node, node->length); > + } > + acpi_put_table(&iort->header); > + return limit; > +} > +#endif > diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h > index 20a32120bb88..7d2e184f0d4d 100644 > --- a/include/linux/acpi_iort.h > +++ b/include/linux/acpi_iort.h > @@ -38,6 +38,7 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *size); > const struct iommu_ops *iort_iommu_configure_id(struct device *dev, > const u32 *id_in); > int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head); > +unsigned int acpi_iort_get_zone_dma_size(void); > #else > static inline void acpi_iort_init(void) { } > static inline u32 iort_msi_map_id(struct device *dev, u32 id) > @@ -55,6 +56,9 @@ static inline const struct iommu_ops *iort_iommu_configure_id( > static inline > int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head *head) > { return 0; } > + > +static inline unsigned int acpi_iort_get_zone_dma_size(void) > +{ return 32; } > #endif > > #endif /* __ACPI_IORT_H__ */ > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel