From mboxrd@z Thu Jan 1 00:00:00 1970 From: Julien Grall Subject: Re: [PATCH] xen/arm: Allow balooning working with 1:1 memory mapping Date: Thu, 14 Nov 2013 16:18:15 +0000 Message-ID: <5284F7C7.2020805@linaro.org> References: <1384442148-12014-1-git-send-email-julien.grall@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta3.messagelabs.com ([195.245.230.39]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Vgzcb-0006eR-4r for xen-devel@lists.xenproject.org; Thu, 14 Nov 2013 16:18:21 +0000 Received: by mail-bk0-f47.google.com with SMTP id mx10so1183309bkb.34 for ; Thu, 14 Nov 2013 08:18:19 -0800 (PST) In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Stefano Stabellini Cc: Keir Fraser , ian.campbell@citrix.com, patches@linaro.org, tim@xen.org, Jan Beulich , xen-devel@lists.xenproject.org List-Id: xen-devel@lists.xenproject.org On 11/14/2013 03:34 PM, Stefano Stabellini wrote: > On Thu, 14 Nov 2013, Julien Grall wrote: >> With the lake of iommu, dom0 must have a 1:1 memory mapping for all >> these guest physical address. When the ballon decides to give back a >> page to the kernel, this page must have the same address as previously. >> Otherwise, we will loose the 1:1 mapping and will break DMA-capable >> device. >> >> Signed-off-by: Julien Grall >> CC: Keir Fraser >> CC: Jan Beulich >> --- >> xen/common/memory.c | 42 ++++++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 40 insertions(+), 2 deletions(-) >> >> diff --git a/xen/common/memory.c b/xen/common/memory.c >> index 50b740f..df36d43 100644 >> --- a/xen/common/memory.c >> +++ b/xen/common/memory.c >> @@ -28,6 +28,9 @@ >> #include >> #include >> #include >> +#ifdef CONFIG_ARM >> +#include >> +#endif >> >> struct memop_args { >> /* INPUT */ >> @@ -90,7 +93,7 @@ static void increase_reservation(struct memop_args *a) >> >> static void populate_physmap(struct memop_args *a) >> { >> - struct page_info *page; >> + struct page_info *page = NULL; >> unsigned long i, j; >> xen_pfn_t gpfn, mfn; >> struct domain *d = a->domain; >> @@ -122,7 +125,33 @@ static void populate_physmap(struct memop_args *a) >> } >> else >> { >> - page = alloc_domheap_pages(d, a->extent_order, a->memflags); >> +#ifdef CONFIG_ARM >> + if ( d == dom0 && platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11) ) >> + { >> + mfn = gpfn; >> + if (!mfn_valid(mfn)) >> + { >> + gdprintk(XENLOG_INFO, "Invalid mfn 0x%"PRI_xen_pfn"\n", >> + mfn); >> + goto out; >> + } >> + >> + page = mfn_to_page(mfn); >> + if ( !get_page(page, d) ) >> + { >> + gdprintk(XENLOG_INFO, >> + "mfn 0x%"PRI_xen_pfn" doesn't belong to dom0\n", >> + mfn); >> + goto out; >> + } >> + put_page(page); >> + } >> + else >> +#endif > > I don't know if the x86 maintainers would like that, but I would prefer > to remove the ifdef CONFIG_ARM. > You just need to define a new function called is_dom0_mapped_11, that > always returns false on x86 and on ARM is implemented by d == dom0 && > platform_has_quirk(PLATFORM_QUIRK_DOM0_MAPPING_11). > Then you can use it on common code. With this solution, it's less clear that it's ARM specific code. We are introducing a workaround that will never be used on x86. I would wait an opinion from other maintainers before sending a new version of this patch. -- Julien Grall