From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH V3] vmx/nmi: Do not use self_nmi() in VMEXIT handler Date: Thu, 22 Nov 2012 16:31:04 +0000 Message-ID: <50AE5348.502@citrix.com> References: <50AE4F8402000078000AAA02@nat28.tlf.novell.com> <50AE41DD.2030703@citrix.com> <50AE511302000078000AAA14@nat28.tlf.novell.com> <50AE46B0.6010807@citrix.com> <50AE590502000078000AAA48@nat28.tlf.novell.com> <50AE4D2C.1040104@citrix.com> <50AE5D1102000078000AAA69@nat28.tlf.novell.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <50AE5D1102000078000AAA69@nat28.tlf.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: Malcolm Crossley , "Tim (Xen.org)" , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 22/11/12 16:12, Jan Beulich wrote: >>>> On 22.11.12 at 17:05, Andrew Cooper wrote: >> On 22/11/12 15:55, Jan Beulich wrote: >>>>>> On 22.11.12 at 16:37, Andrew Cooper wrote: >>>> A quick solution would be to execute a noop function with >>>> run_in_exception_handler(). Alternatively, I can code enable_nmi() or >>>> so which does an inline iret to itself. Which of these would you prefer? >>> I would actually consider avoiding to run softirqs altogether in that >>> case, just like native Linux doesn't do any event or scheduler >>> processing in that case. >> That would probably be the easiest solution. >> >> I was already going to do the same for the rentrant NMI and MCE handling >> case (and also the process pending upcalls checking), due to the >> complexities of fixing the race condition at the end of the handler. >> >> Unfortunately, I don't think I have time to look at this issue >> immediately, but if it is ok to wait till the beginning of next week, I > That's fine of course. > >> can roll it into the main dev work for the other NMI/MCE work. > Hmm, that would mean it's going to be more difficult to backport. > I'd prefer having this in as simple a fashion as possible in the > patch here, and then have your other patch(es) build on top of > that. > > Jan > I will ensure that the fix for this is suitably separate in the patch series, and in the easiest backportable form. -- Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer T: +44 (0)1223 225 900, http://www.citrix.com