From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp01.au.ibm.com (e23smtp01.au.ibm.com [202.81.31.143]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id BEAAE1A02AE for ; Thu, 12 Jun 2014 14:50:29 +1000 (EST) Received: from /spool/local by e23smtp01.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 12 Jun 2014 14:50:28 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp01.au.ibm.com (Postfix) with ESMTP id 7E59C2CE8054 for ; Thu, 12 Jun 2014 14:50:26 +1000 (EST) Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s5C4SOVt51380266 for ; Thu, 12 Jun 2014 14:28:24 +1000 Received: from d23av02.au.ibm.com (localhost [127.0.0.1]) by d23av02.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s5C4oOW3030217 for ; Thu, 12 Jun 2014 14:50:26 +1000 From: "Aneesh Kumar K.V" To: Joonsoo Kim , Andrew Morton , Marek Szyprowski , Michal Nazarewicz Subject: Re: [PATCH v2 04/10] DMA, CMA: support alignment constraint on cma region In-Reply-To: <1402543307-29800-5-git-send-email-iamjoonsoo.kim@lge.com> References: <1402543307-29800-1-git-send-email-iamjoonsoo.kim@lge.com> <1402543307-29800-5-git-send-email-iamjoonsoo.kim@lge.com> Date: Thu, 12 Jun 2014 10:20:18 +0530 Message-ID: <87oaxypw8l.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Cc: Russell King - ARM Linux , kvm@vger.kernel.org, linux-mm@kvack.org, Gleb Natapov , Greg Kroah-Hartman , Alexander Graf , kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Minchan Kim , Paul Mackerras , Paolo Bonzini , Joonsoo Kim , linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Joonsoo Kim writes: > ppc kvm's cma area management needs alignment constraint on > cma region. So support it to prepare generalization of cma area > management functionality. > > Additionally, add some comments which tell us why alignment > constraint is needed on cma region. > > Signed-off-by: Joonsoo Kim Reviewed-by: Aneesh Kumar K.V > > diff --git a/drivers/base/dma-contiguous.c b/drivers/base/dma-contiguous.c > index 8a44c82..bc4c171 100644 > --- a/drivers/base/dma-contiguous.c > +++ b/drivers/base/dma-contiguous.c > @@ -32,6 +32,7 @@ > #include > #include > #include > +#include > > struct cma { > unsigned long base_pfn; > @@ -219,6 +220,7 @@ core_initcall(cma_init_reserved_areas); > * @size: Size of the reserved area (in bytes), > * @base: Base address of the reserved area optional, use 0 for any > * @limit: End address of the reserved memory (optional, 0 for any). > + * @alignment: Alignment for the contiguous memory area, should be power of 2 > * @res_cma: Pointer to store the created cma region. > * @fixed: hint about where to place the reserved area > * > @@ -233,15 +235,15 @@ core_initcall(cma_init_reserved_areas); > */ > static int __init __dma_contiguous_reserve_area(phys_addr_t size, > phys_addr_t base, phys_addr_t limit, > + phys_addr_t alignment, > struct cma **res_cma, bool fixed) > { > struct cma *cma = &cma_areas[cma_area_count]; > - phys_addr_t alignment; > int ret = 0; > > - pr_debug("%s(size %lx, base %08lx, limit %08lx)\n", __func__, > - (unsigned long)size, (unsigned long)base, > - (unsigned long)limit); > + pr_debug("%s(size %lx, base %08lx, limit %08lx align_order %08lx)\n", > + __func__, (unsigned long)size, (unsigned long)base, > + (unsigned long)limit, (unsigned long)alignment); > > /* Sanity checks */ > if (cma_area_count == ARRAY_SIZE(cma_areas)) { > @@ -253,8 +255,17 @@ static int __init __dma_contiguous_reserve_area(phys_addr_t size, > if (!size) > return -EINVAL; > > - /* Sanitise input arguments */ > - alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order); > + if (alignment && !is_power_of_2(alignment)) > + return -EINVAL; > + > + /* > + * Sanitise input arguments. > + * CMA area should be at least MAX_ORDER - 1 aligned. Otherwise, > + * CMA area could be merged into other MIGRATE_TYPE by buddy mechanism > + * and CMA property will be broken. > + */ > + alignment = max(alignment, > + (phys_addr_t)PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order)); > base = ALIGN(base, alignment); > size = ALIGN(size, alignment); > limit &= ~(alignment - 1); > @@ -302,7 +313,8 @@ int __init dma_contiguous_reserve_area(phys_addr_t size, phys_addr_t base, > { > int ret; > > - ret = __dma_contiguous_reserve_area(size, base, limit, res_cma, fixed); > + ret = __dma_contiguous_reserve_area(size, base, limit, 0, > + res_cma, fixed); > if (ret) > return ret; > > -- > 1.7.9.5