From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zachary Amsden Subject: Re: [announce] [patch] KVM paravirtualization for Linux Date: Fri, 05 Jan 2007 14:15:19 -0800 Message-ID: <459ECDF7.9040309@vmware.com> References: <20070105215223.GA5361@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Return-path: To: Ingo Molnar In-Reply-To: <20070105215223.GA5361-X9Un+BFzKDI@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Ingo Molnar wrote: > i'm pleased to announce the first release of paravirtualized KVM (Linux > under Linux), which includes support for the hardware cr3-cache feature > of Intel-VMX CPUs. (which speeds up context switches and TLB flushes) > > the patch is against 2.6.20-rc3 + KVM trunk and can be found at: > > http://redhat.com/~mingo/kvm-paravirt-patches/ > > Some aspects of the code are still a bit ad-hoc and incomplete, but the > code is stable enough in my testing and i'd like to have some feedback. > Your code looks generally good. I have some comments. You can't do this, even though you want to: -EXPORT_SYMBOL(paravirt_ops); +EXPORT_SYMBOL_GPL(paravirt_ops); The problem is it makes all modules GPL - or at least all modules that use any kind of locking, pull in the basic definitions to enable and disable interrupts, thus the paravirt_ops symbol, so basically all modules. What you really want is more like EXPORT_SYMBOL_READABLE_GPL(paravirt_ops); But I'm not sure that is technically feasible yet. The kvm code should probably go in kvm.c instead of paravirt.c. Index: linux/drivers/serial/8250.c =================================================================== --- linux.orig/drivers/serial/8250.c +++ linux/drivers/serial/8250.c @@ -1371,7 +1371,7 @@ static irqreturn_t serial8250_interrupt( l = l->next; - if (l == i->head && pass_counter++ > PASS_LIMIT) { + if (!kvm_paravirt Is this a bug that might happen under other virtualizations as well, not just kvm? Perhaps it deserves a disable feature instead of a kvm specific check. Which also gets rid of the need for this unusually placed extern: Index: linux/include/linux/sched.h =================================================================== --- linux.orig/include/linux/sched.h +++ linux/include/linux/sched.h @@ -1911,6 +1911,11 @@ static inline void set_task_cpu(struct t #endif /* CONFIG_SMP */ +/* + * Is paravirtualization active? + */ +extern int kvm_paravirt; + ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV