From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH 0 of 1] Kexec alteration Date: Thu, 6 Dec 2012 16:01:40 +0000 Message-ID: <50C0C164.9010303@citrix.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 06/12/12 15:56, Andrew Cooper wrote: > Hello, > > Fixing the root reentrant NMI/MCE issues is quickly turning into a > substantially larger problem than initially thought. > > As a result, I have decided to submit the fixes in smaller chunks, in > the hope that they are reviewed and integrated separately. The first > part is changes to the kexec path, from which I am now happy to drop the > RFC tag. > > Please scrutinise carefully. > > > The vague decided plan going forwards is: > > * Implement spin_{un,}lock_recursive_irq{save,restore}() > * Audit users of mixed regular/recursive calls on the same spinlock > * Swap recursive spinlocks to be a separate type > * Fix the semantics of console_force_unlock * Fix ASSERT() and BUG() to be NMI/MCE safe wrt console > * Continue audit of NMI and MCE paths, with console semantics fixed > * {Panic,NMI,MCE}-in-progress flags & reentrancy protection > * Ability to specify whether iret should be used on trap exit > * Implement "MCEs never iret, NMIs always iret" policy > > The plan for "things I think needs to happen" is: > * Extend spinlock debugging to know about NMI and MCE contexts > * Implement strict ordering constraints for spinlock debugging > > The "other things needing investigating" list includes: > * Interaction of paging changes and IDTs while purgatory is changing > processor modes > > ~Andrew -- Andrew Cooper - Dom0 Kernel Engineer, Citrix XenServer T: +44 (0)1223 225 900, http://www.citrix.com