From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Catterall Subject: Re: [RFC 1/4] HVM x86 deprivileged mode: Page allocation helper Date: Fri, 7 Aug 2015 10:57:18 +0100 Message-ID: <55C480FE.9010802@citrix.com> References: <1438879519-564-1-git-send-email-Ben.Catterall@citrix.com> <1438879519-564-2-git-send-email-Ben.Catterall@citrix.com> <55C3B3F3.7000804@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55C3B3F3.7000804@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Andrew Cooper , xen-devel@lists.xensource.com Cc: george.dunlap@eu.citrix.com, tim@xen.org, keir@xen.org, ian.campbell@citrix.com, jbeulich@suse.com List-Id: xen-devel@lists.xenproject.org On 06/08/15 20:22, Andrew Cooper wrote: > On 06/08/15 17:45, Ben Catterall wrote: >> This allocation function is used by the deprivileged mode initialisation code >> to allocate pages for the new page table mappings and page frames on the HAP >> page heap. >> >> Signed-off-by: Ben Catterall > This is fine for your test box, but isn't fine for systems out there > without hardware EPT/NPT support. For older systems like that (or in > certain specific workloads), shadow paging is used instead. > > This feature is applicable to any HVM domain, which means that it > shouldn't depend on HAP or shadow paging. > > How much memory is allocated for the depriv area, and what exactly is > allocated in total? So, per-vcpu: - a user mode stack which, from your comments in [RFC 2/4], can be 2 pages - local data (may or may not be needed, depends on the device) which will be around a page or two. Text segment: as per your comments in RFC 2/4, this will be changed to be an alias so no extra memory. > I expect it isn't very much, and would suggest using > d->arch.paging.alloc_page() instead (which is the generic "get me some > memory accounted against the domain" helper) which looks as if it should > suffice. > > Depending on exactly how much memory is needed, you might need to bump > the default minimum shadow pool size. > > ~Andrew Ok, will do. That will also solve the EPT/NPT problem, thanks! Ben