From mboxrd@z Thu Jan 1 00:00:00 1970 From: Boris Ostrovsky Subject: Re: [PATCH v4 2/4] x86/compat: Test both PV and PVH guests for compat mode Date: Tue, 01 Sep 2015 20:53:55 -0400 Message-ID: <55E648A3.90104@oracle.com> References: <1439489529-3633-1-git-send-email-boris.ostrovsky@oracle.com> <1439489529-3633-3-git-send-email-boris.ostrovsky@oracle.com> <55DF5082020000780009D8A3@prv-mh.provo.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <55DF5082020000780009D8A3@prv-mh.provo.novell.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: Jan Beulich Cc: elena.ufimtseva@oracle.com, wei.liu2@citrix.com, ian.campbell@citrix.com, stefano.stabellini@eu.citrix.com, andrew.cooper3@citrix.com, ian.jackson@eu.citrix.com, xen-devel@lists.xen.org, roger.pau@citrix.com List-Id: xen-devel@lists.xenproject.org On 08/27/2015 12:01 PM, Jan Beulich wrote: >>>> On 13.08.15 at 20:12, wrote: >> @@ -777,7 +777,7 @@ int arch_set_info_guest( >> >> /* The context is a compat-mode one if the target domain is compat-mode; >> * we expect the tools to DTRT even in compat-mode callers. */ >> - compat = is_pv_32bit_domain(d); >> + compat = is_pv_32bit_domain(d) || is_pvh_32bit_domain(d); > I continue to think that this should include a v->domain == > current->domain check (to match behavior for HVM guests > from the tool stack perspective). Having looked at patch 4, I also > can't see how the tool stack is being made expect a non-native > guest context record in the 32-bit PVH case (i.e. I'd appreciate > if you could point out where that hides). For vcpu 0 current->domain is dom0 so I am not sure how this check would work. For a 32-bit PVH guest the toolstack will place data into vcpu_guest_context_x86_32_t (in vcpu_x86_32()) and so the hypervisor, knowing that the guest is a compat one (based on the test above), will access appropriate fields. This is not how HVM guests are started --- "classic" PVH behaves very much like a PV guest, unlike what we are doing with no-dm PVH. -boris