From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 40G9kp6N3HzF1pZ for ; Wed, 4 Apr 2018 13:03:11 +1000 (AEST) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id w342xnLK076660 for ; Tue, 3 Apr 2018 23:03:08 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0a-001b2d01.pphosted.com with ESMTP id 2h4nw9s3ks-1 (version=TLSv1.2 cipher=AES256-SHA256 bits=256 verify=NOT) for ; Tue, 03 Apr 2018 23:03:08 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 4 Apr 2018 04:03:06 +0100 From: Anshuman Khandual To: linuxppc-dev@lists.ozlabs.org Subject: [RFC 1/2] powerpc/swiotlb: Dont free up allocated SWIOTLB slab on POWER Date: Wed, 4 Apr 2018 08:33:00 +0530 Message-Id: <20180404030301.25019-1-khandual@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Even though SWIOTLB slab gets allocated and initialized on powerpc with swiotlb_init() called during mem_init(), it gets released away again on POWER platform because 'ppc_swiotlb_enable' never gets set. The function swiotlb_detect_4g() checks for 4GB memory and then sets the variable 'ppc_swiotlb_enable' which prevents freeing up the SWIOTLB slab. Lets make POWER platform call swiotlb_detect_4g() during setup_arch() which will keep the SWIOTLB slab through out the runtime. A previous commit cf5621032f ("powerpc/64: Limit ZONE_DMA32 to 4GiB in swiotlb_detect_4g()") enforced 4GB limit on ZONE_DMA32 which is is not applicable on POWER (CONFIG_PPC_BOOK3S_64) platform. Lets remove this unnecessary restriction. After the patch, SWIOTLB slab does not get released. [0.410992] software IO TLB [mem 0xfbff0000-0xffff0000] (64MB) mapped at [00000000767f6cb3-000000004a10114f] Signed-off-by: Anshuman Khandual --- arch/powerpc/kernel/dma-swiotlb.c | 2 +- arch/powerpc/kernel/setup-common.c | 1 + 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/kernel/dma-swiotlb.c b/arch/powerpc/kernel/dma-swiotlb.c index 88f3963ca30f..2255c6dc89db 100644 --- a/arch/powerpc/kernel/dma-swiotlb.c +++ b/arch/powerpc/kernel/dma-swiotlb.c @@ -110,7 +110,7 @@ void __init swiotlb_detect_4g(void) { if ((memblock_end_of_DRAM() - 1) > 0xffffffff) { ppc_swiotlb_enable = 1; -#ifdef CONFIG_ZONE_DMA32 +#if defined(CONFIG_ZONE_DMA32) && !defined(CONFIG_PPC_BOOK3S_64) limit_zone_pfn(ZONE_DMA32, (1ULL << 32) >> PAGE_SHIFT); #endif } diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c index d73ec518ef80..c4db844e0b0d 100644 --- a/arch/powerpc/kernel/setup-common.c +++ b/arch/powerpc/kernel/setup-common.c @@ -944,6 +944,7 @@ void __init setup_arch(char **cmdline_p) /* Initialize the MMU context management stuff. */ mmu_context_init(); + swiotlb_detect_4g(); #ifdef CONFIG_PPC64 /* Interrupt code needs to be 64K-aligned. */ if ((unsigned long)_stext & 0xffff) -- 2.14.1