From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [[RFC PATCH 2/8]: PVH: changes related to initial boot and irq rewiring Date: Sat, 18 Aug 2012 09:23:21 +0100 Message-ID: <1345278201.23624.13.camel@dagon.hellion.org.uk> References: <20120815180131.24aaa5ce@mantra.us.oracle.com> <1345193780.30865.109.camel@zakaz.uk.xensource.com> <20120817163739.386fce5d@mantra.us.oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120817163739.386fce5d@mantra.us.oracle.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: Mukesh Rathor Cc: "Xen-devel@lists.xensource.com" , Konrad Rzeszutek Wilk List-Id: xen-devel@lists.xenproject.org > > > diff --git a/arch/x86/xen/irq.c b/arch/x86/xen/irq.c > > > index 1573376..7c7dfd1 100644 > > > --- a/arch/x86/xen/irq.c > > > +++ b/arch/x86/xen/irq.c > > > @@ -100,6 +100,10 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_irq_enable); > > > > > > static void xen_safe_halt(void) > > > { > > > + /* so event channel can be delivered to us, since in HVM > > > container */ > > > + if (xen_pvh_domain()) > > > + local_irq_enable(); > > > + > > > /* Blocking includes an implicit local_irq_enable(). */ > > > > So this comment isn't true for a PVH guest? Why not? Should it be? > > I need to make sure the EFLAGS.IF is enabled. IIRC, the comment is saying > that xen will clear event channel mask bit. For PVH, there's the additional > EFLAGS.IF flag. > My reading of the hypercall semantics would be that it reenables whichever event delivery mechanism the guest is using and therefore it should enable EFLAGS.IF for a PVH guest since manipulating the evtchn mask in this case is pointless. Ian.