From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH] kvm, x86: Properly check whether a pfn is an MMIO or not Date: Thu, 15 Sep 2016 18:22:41 +0200 Message-ID: <2ca7f677-723e-b96d-64aa-e2d858df7930@redhat.com> References: <1466562866-31524-1-git-send-email-karahmed@amazon.de> <6b30fd96-dc04-13a2-aa8b-7760a85337c6@redhat.com> <85E2C33C-8873-4CC8-8D31-9A85C30F8DB5@amazon.de> <1473955392.2092.76.camel@hpe.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "bp@suse.de" , "tglx@linutronix.de" , "x86@kernel.org" , "akpm@linux-foundation.org" , "hpa@zytor.com" , "mingo@redhat.com" , "tony.luck@intel.com" , "dvlasenk@redhat.com" , "rkrcmar@redhat.com" To: "Kani, Toshimitsu" , "karahmed@amazon.de" Return-path: In-Reply-To: <1473955392.2092.76.camel@hpe.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 15/09/2016 18:04, Kani, Toshimitsu wrote: > On Thu, 2016-09-15 at 08:22 +0200, Paolo Bonzini wrote: >> >> On 15/09/2016 07:54, Raslan, KarimAllah wrote: >>> >>> >>>> >>>> On Jun 22, 2016, at 3:41 PM, Paolo Bonzini >>>> wrote: >>>> >>>> >>>> >>>> On 22/06/2016 04:34, KarimAllah Ahmed wrote: >>>>> >>>>> pfn_valid check is not sufficient because it only checks if a >>>>> page has a struct page or not, if for example "mem=" was passed >>>>> to the kernel some valid pages won't have a struct page. This >>>>> means that if guests were assigned valid memory that lies after >>>>> the mem= boundary it will be passed uncached to the guest no >>>>> matter what the guest caching attributes are for this memory. >>>> >>>> How can you pass memory after the mem= boundary to the guest? >>> >>> Does my previous reply answer your question? >> >> Yes, but I'm not sure it's the right way to do it. Looking at the >> e820 memory map seems pretty hacky. > > Can you use region_intersects() for this check? See memremap() as an > example using this interface. This one seems more generic but very slow. Paolo