From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Campbell Subject: Re: [PATCH 4/9] xen: arm: turn vtimer traps for cp32/64 and sysreg into #undef Date: Thu, 15 Jan 2015 12:35:26 +0000 Message-ID: <1421325326.19103.349.camel@citrix.com> References: <1410279730.8217.238.camel@kazak.uk.xensource.com> <1410279788-27167-4-git-send-email-ian.campbell@citrix.com> <540F8DC3.3050305@linaro.org> <1410342387.8217.272.camel@kazak.uk.xensource.com> <54109E68.7020102@linaro.org> <1410424998.6166.25.camel@kazak.uk.xensource.com> <1421253201.19103.296.camel@citrix.com> <54B6A005.4000602@linaro.org> <1421317598.19103.326.camel@citrix.com> <54B7B23D.8050809@linaro.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <54B7B23D.8050809@linaro.org> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Julien Grall Cc: xen-devel@lists.xen.org, Tim Deegan , stefano.stabellini@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On Thu, 2015-01-15 at 12:27 +0000, Julien Grall wrote: > Hi Ian, > > On 15/01/15 10:26, Ian Campbell wrote: > > I'm looking into the vtimer masking and ctxt switching the irq state > > now, once I've got that going exposing the ptimer directly to guests > > ought to be pretty simple. > > I don't think we can expose directly the physical timer to the guest. > > If the guest tries to read CNTPCT_EL0, it will read the number of ticks > since the host is up. Yes, and they should expect that I think, that's the point of the distinction between v and p timer. Of course maybe by providing it with an offset until now maybe we've painted ourselves into a corner, which sucks :-/ Ian.