From patchwork Wed Oct 14 19:12:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nicolas Saenz Julienne X-Patchwork-Id: 284855 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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 EB138C433E7 for ; Wed, 14 Oct 2020 19:12:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A441A2222C for ; Wed, 14 Oct 2020 19:12:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390434AbgJNTMo (ORCPT ); Wed, 14 Oct 2020 15:12:44 -0400 Received: from mx2.suse.de ([195.135.220.15]:52368 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390320AbgJNTMZ (ORCPT ); Wed, 14 Oct 2020 15:12:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 53FAAAD43; Wed, 14 Oct 2020 19:12:24 +0000 (UTC) From: Nicolas Saenz Julienne To: robh+dt@kernel.org, catalin.marinas@arm.com, hch@lst.de, ardb@kernel.org, linux-kernel@vger.kernel.org, Lorenzo Pieralisi , Hanjun Guo , Sudeep Holla Cc: robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org, linux-rpi-kernel@lists.infradead.org, jeremy.linton@arm.com, iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, Nicolas Saenz Julienne , Anshuman Khandual , Will Deacon , "Rafael J. Wysocki" , Len Brown , linux-acpi@vger.kernel.org Subject: [PATCH v3 7/8] arm64: mm: Set ZONE_DMA size based on early IORT scan Date: Wed, 14 Oct 2020 21:12:09 +0200 Message-Id: <20201014191211.27029-8-nsaenzjulienne@suse.de> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201014191211.27029-1-nsaenzjulienne@suse.de> References: <20201014191211.27029-1-nsaenzjulienne@suse.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org 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. 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); + 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__ */