From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH RFC 6/9] xen, libxc: Request page fault injection via libxc Date: Wed, 2 Jul 2014 17:00:08 +0100 Message-ID: <53B42C88.4000101@citrix.com> References: <1404308041-15461-1-git-send-email-rcojocaru@bitdefender.com> <1404308041-15461-6-git-send-email-rcojocaru@bitdefender.com> <53B4468D020000780001FB40@mail.emea.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <53B4468D020000780001FB40@mail.emea.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 , Razvan Cojocaru Cc: tim@xen.org, xen-devel@lists.xen.org List-Id: xen-devel@lists.xenproject.org On 02/07/14 16:51, Jan Beulich wrote: >>>> On 02.07.14 at 15:33, wrote: >> Added new XEN_DOMCTL_set_pagefault_info hypercall, used by libxc's >> new xc_domain_set_pagefault_info() function to set per-domain page >> fault injection information. This information is then used to call >> hvm_inject_page_fault() at the first VMENTRY where the guest status >> matches and there are no other pending traps. > So the first question that strikes me here: What good can it do to be > able to inject arbitrary page faults, possibly at times where the guest > OS is absolutely not expecting them? I would further this by suggesting that the only plausible case where you could inject a pagefault is as a reply to a mem_event for which the guest is already paused. In which case it it would be better implemented as part of the mem_event protocol than a plain hypercall in its own regard. ~Andrew