From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751731AbaKJS1M (ORCPT ); Mon, 10 Nov 2014 13:27:12 -0500 Received: from foss-mx-na.foss.arm.com ([217.140.108.86]:55724 "EHLO foss-mx-na.foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751669AbaKJS1K (ORCPT ); Mon, 10 Nov 2014 13:27:10 -0500 Date: Mon, 10 Nov 2014 18:27:00 +0000 From: Catalin Marinas To: Stefano Stabellini Cc: "xen-devel@lists.xensource.com" , "konrad.wilk@oracle.com" , "Ian.Campbell@citrix.com" , "david.vrabel@citrix.com" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [PATCH v8 08/13] xen/arm: use hypercall to flush caches in map_page Message-ID: <20141110182659.GE25609@e104818-lin.cambridge.arm.com> References: <1415636045-24669-8-git-send-email-stefano.stabellini@eu.citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1415636045-24669-8-git-send-email-stefano.stabellini@eu.citrix.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 10, 2014 at 04:14:00PM +0000, Stefano Stabellini wrote: > In xen_dma_map_page, if the page is a local page, call the native > map_page dma_ops. If the page is foreign, call __xen_dma_map_page that > issues any required cache maintenane operations via hypercall. > > The reason for doing this is that the native dma_ops map_page could > allocate buffers than need to be freed. If the page is foreign we don't > call the native unmap_page dma_ops function, resulting in a memory leak. > > Suggested-by: Catalin Marinas > Signed-off-by: Stefano Stabellini > --- > arch/arm/include/asm/xen/page-coherent.h | 9 ++++++++- > arch/arm/xen/mm32.c | 12 ++++++++++++ > 2 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/include/asm/xen/page-coherent.h b/arch/arm/include/asm/xen/page-coherent.h > index 25d450c..36b79a8 100644 > --- a/arch/arm/include/asm/xen/page-coherent.h > +++ b/arch/arm/include/asm/xen/page-coherent.h > @@ -5,6 +5,9 @@ > #include > #include > > +void __xen_dma_map_page(struct device *hwdev, struct page *page, > + dma_addr_t dev_addr, unsigned long offset, size_t size, > + enum dma_data_direction dir, struct dma_attrs *attrs); > void __xen_dma_unmap_page(struct device *hwdev, dma_addr_t handle, > size_t size, enum dma_data_direction dir, > struct dma_attrs *attrs); > @@ -32,7 +35,11 @@ static inline void xen_dma_map_page(struct device *hwdev, struct page *page, > dma_addr_t dev_addr, unsigned long offset, size_t size, > enum dma_data_direction dir, struct dma_attrs *attrs) > { > - __generic_dma_ops(hwdev)->map_page(hwdev, page, offset, size, dir, attrs); > + if (PFN_DOWN(dev_addr) == page_to_pfn(page)) { Nitpick: you could write: bool foreign = PFN_DOWN(dev_addr) == page_to_pfn(page); or even a static inline xen_foreign_page(page, dev_addr) function for clarity. This code lacks comments. > + if (__generic_dma_ops(hwdev)->map_page) I'm not sure we need to check map_page() here. I thought it's always present as host DMA API does not check for it. -- Catalin