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: Mon, 25 Nov 2013 17:30:44 +0000 Message-ID: <52938944.4050400@linaro.org> References: <1384442148-12014-1-git-send-email-julien.grall@linaro.org> <5284F7C7.2020805@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail6.bemta14.messagelabs.com ([193.109.254.103]) by lists.xen.org with esmtp (Exim 4.72) (envelope-from ) id 1Vkzzk-0003U4-IO for xen-devel@lists.xenproject.org; Mon, 25 Nov 2013 17:30:48 +0000 Received: by mail-we0-f171.google.com with SMTP id q58so4153011wes.16 for ; Mon, 25 Nov 2013 09:30:46 -0800 (PST) In-Reply-To: <5284F7C7.2020805@linaro.org> 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 04:18 PM, Julien Grall wrote: > > > 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. > Ping, any input for X86 maintainers (Keir, Jan)? -- Julien Grall