Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934214Ab2KZRVV (ORCPT ); Mon, 26 Nov 2012 12:21:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:1298 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933397Ab2KZRVQ (ORCPT ); Mon, 26 Nov 2012 12:21:16 -0500 Date: Mon, 26 Nov 2012 19:20:54 +0200 From: Gleb Natapov To: "Eric W. Biederman" Cc: Zhang Yanfei , "x86@kernel.org" , "kexec@lists.infradead.org" , Marcelo Tosatti , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v8 1/2] x86/kexec: add a new atomic notifier list for kdump Message-ID: <20121126172054.GF12969@redhat.com> References: <50ADE0C2.1000106@cn.fujitsu.com> <50ADE11A.401@cn.fujitsu.com> <87ip8sxuyh.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87ip8sxuyh.fsf@xmission.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3213 Lines: 92 On Mon, Nov 26, 2012 at 09:08:54AM -0600, Eric W. Biederman wrote: > Zhang Yanfei writes: > > > This patch adds an atomic notifier list named crash_notifier_list. > > Currently, when loading kvm-intel module, a notifier will be registered > > in the list to enable vmcss loaded on all cpus to be VMCLEAR'd if > > needed. > > crash_notifier_list ick gag please no. Effectively this makes the kexec > on panic code path undebuggable. > > Instead we need to use direct function calls to whatever you are doing. > The code walks linked list in kvm-intel module and calls vmclear on whatever it finds there. Since the function have to resides in kvm-intel module it cannot be called directly. Is callback pointer that is set by kvm-intel more acceptable? > If a direct function call is too complex then the piece of code you want > to call is almost certainly too complex to be calling on a code path > like this. > > Eric > > > Signed-off-by: Zhang Yanfei > > --- > > arch/x86/include/asm/kexec.h | 2 ++ > > arch/x86/kernel/crash.c | 9 +++++++++ > > 2 files changed, 11 insertions(+), 0 deletions(-) > > > > diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h > > index 317ff17..5e22b00 100644 > > --- a/arch/x86/include/asm/kexec.h > > +++ b/arch/x86/include/asm/kexec.h > > @@ -163,6 +163,8 @@ struct kimage_arch { > > }; > > #endif > > > > +extern struct atomic_notifier_head crash_notifier_list; > > + > > #endif /* __ASSEMBLY__ */ > > > > #endif /* _ASM_X86_KEXEC_H */ > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > > index 13ad899..c5b2f70 100644 > > --- a/arch/x86/kernel/crash.c > > +++ b/arch/x86/kernel/crash.c > > @@ -16,6 +16,8 @@ > > #include > > #include > > #include > > +#include > > +#include > > > > #include > > #include > > @@ -30,6 +32,9 @@ > > > > int in_crash_kexec; > > > > +ATOMIC_NOTIFIER_HEAD(crash_notifier_list); > > +EXPORT_SYMBOL_GPL(crash_notifier_list); > > + > > #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) > > > > static void kdump_nmi_callback(int cpu, struct pt_regs *regs) > > @@ -46,6 +51,8 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) > > #endif > > crash_save_cpu(regs, cpu); > > > > + atomic_notifier_call_chain(&crash_notifier_list, 0, NULL); > > + > > /* Disable VMX or SVM if needed. > > * > > * We need to disable virtualization on all CPUs. > > @@ -88,6 +95,8 @@ void native_machine_crash_shutdown(struct pt_regs *regs) > > > > kdump_nmi_shootdown_cpus(); > > > > + atomic_notifier_call_chain(&crash_notifier_list, 0, NULL); > > + > > /* Booting kdump kernel with VMX or SVM enabled won't work, > > * because (among other limitations) we can't disable paging > > * with the virt flags. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/