From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexey Kardashevskiy Date: Tue, 18 Feb 2020 07:36:48 +0000 Subject: [PATCH kernel 3/5] powerpc/powernv/ioda: Allow smaller TCE table levels Message-Id: <20200218073650.16149-4-aik@ozlabs.ru> List-Id: References: <20200218073650.16149-1-aik@ozlabs.ru> In-Reply-To: <20200218073650.16149-1-aik@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linuxppc-dev@lists.ozlabs.org Cc: Alexey Kardashevskiy , Alistair Popple , Alex Williamson , kvm-ppc@vger.kernel.org, David Gibson Now the minimum allocation size for a TCE table level is PAGE_SIZE (64k) as this is the minimum for alloc_pages(). The limit was set in POWER8 where we did not have sparse RAM so we did not need sparse TCE tables. On POWER9 we have gaps in the phys address space for which using multi level TCE tables makes sense. The problem with that is that 64K per level is too much for 2 levels and 1GB pages as it exceeds the hardware limit of 55bits so we need smaller levels. This drops the minimum level size to 4K. For a machine with 2 CPUs, top RAM address 0x4000.0000.0000 (each node gets 32TiB) and 1GiB IOMMU pages: Before the patch: 512KiB or 8 pages. After the patch: 3 pages: one level1 + 2xlevel2 tables, each can map up to 64k>>3<<30 = 8TiB of physical space. Signed-off-by: Alexey Kardashevskiy --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index 5dc6847d5f4c..82e680da9d94 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -37,7 +37,7 @@ static __be64 *pnv_alloc_tce_level(int nid, unsigned int shift) __be64 *addr; tce_mem = alloc_pages_node(nid, GFP_ATOMIC | __GFP_NOWARN, - shift - PAGE_SHIFT); + shift > PAGE_SHIFT ? shift - PAGE_SHIFT : 0); if (!tce_mem) { pr_err("Failed to allocate a TCE memory, level shift=%d\n", shift); @@ -282,7 +282,7 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, /* Adjust direct table size from window_size and levels */ entries_shift = (entries_shift + levels - 1) / levels; level_shift = entries_shift + 3; - level_shift = max_t(unsigned int, level_shift, PAGE_SHIFT); + level_shift = max_t(unsigned int, level_shift, 12); /* 4K is minimum */ if ((level_shift - 3) * levels + page_shift >= 55) return -EINVAL; -- 2.17.1 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=-8.1 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLACK,USER_AGENT_GIT autolearn=ham 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 A6F72C34031 for ; Tue, 18 Feb 2020 07:38:57 +0000 (UTC) Received: from lists.ozlabs.org (unknown [203.11.71.2]) (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 1B4F321D7D for ; Tue, 18 Feb 2020 07:38:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1B4F321D7D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 48MCQl1SQczDqWF for ; Tue, 18 Feb 2020 18:38:55 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.ru (client-ip=107.174.27.60; helo=ozlabs.ru; envelope-from=aik@ozlabs.ru; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from ozlabs.ru (unknown [107.174.27.60]) by lists.ozlabs.org (Postfix) with ESMTP id 48MCNX4Xm1zDq83 for ; Tue, 18 Feb 2020 18:37:00 +1100 (AEDT) Received: from fstn1-p1.ozlabs.ibm.com (localhost [IPv6:::1]) by ozlabs.ru (Postfix) with ESMTP id 60ACDAE8056D; Tue, 18 Feb 2020 02:35:26 -0500 (EST) From: Alexey Kardashevskiy To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH kernel 3/5] powerpc/powernv/ioda: Allow smaller TCE table levels Date: Tue, 18 Feb 2020 18:36:48 +1100 Message-Id: <20200218073650.16149-4-aik@ozlabs.ru> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200218073650.16149-1-aik@ozlabs.ru> References: <20200218073650.16149-1-aik@ozlabs.ru> X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Alexey Kardashevskiy , Alistair Popple , Alex Williamson , kvm-ppc@vger.kernel.org, David Gibson Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Now the minimum allocation size for a TCE table level is PAGE_SIZE (64k) as this is the minimum for alloc_pages(). The limit was set in POWER8 where we did not have sparse RAM so we did not need sparse TCE tables. On POWER9 we have gaps in the phys address space for which using multi level TCE tables makes sense. The problem with that is that 64K per level is too much for 2 levels and 1GB pages as it exceeds the hardware limit of 55bits so we need smaller levels. This drops the minimum level size to 4K. For a machine with 2 CPUs, top RAM address 0x4000.0000.0000 (each node gets 32TiB) and 1GiB IOMMU pages: Before the patch: 512KiB or 8 pages. After the patch: 3 pages: one level1 + 2xlevel2 tables, each can map up to 64k>>3<<30 = 8TiB of physical space. Signed-off-by: Alexey Kardashevskiy --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index 5dc6847d5f4c..82e680da9d94 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -37,7 +37,7 @@ static __be64 *pnv_alloc_tce_level(int nid, unsigned int shift) __be64 *addr; tce_mem = alloc_pages_node(nid, GFP_ATOMIC | __GFP_NOWARN, - shift - PAGE_SHIFT); + shift > PAGE_SHIFT ? shift - PAGE_SHIFT : 0); if (!tce_mem) { pr_err("Failed to allocate a TCE memory, level shift=%d\n", shift); @@ -282,7 +282,7 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, /* Adjust direct table size from window_size and levels */ entries_shift = (entries_shift + levels - 1) / levels; level_shift = entries_shift + 3; - level_shift = max_t(unsigned int, level_shift, PAGE_SHIFT); + level_shift = max_t(unsigned int, level_shift, 12); /* 4K is minimum */ if ((level_shift - 3) * levels + page_shift >= 55) return -EINVAL; -- 2.17.1