From patchwork Tue Feb 18 07:36:48 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexey Kardashevskiy X-Patchwork-Id: 1239798 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (no SPF record) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=ozlabs.ru Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 48MCZq0bc9z9sT9 for ; Tue, 18 Feb 2020 18:45:55 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726283AbgBRHpx (ORCPT ); Tue, 18 Feb 2020 02:45:53 -0500 Received: from 107-174-27-60-host.colocrossing.com ([107.174.27.60]:37208 "EHLO ozlabs.ru" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1726105AbgBRHpx (ORCPT ); Tue, 18 Feb 2020 02:45:53 -0500 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 Cc: David Gibson , kvm-ppc@vger.kernel.org, Alistair Popple , Alex Williamson , Alexey Kardashevskiy 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> Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org 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;