From mboxrd@z Thu Jan 1 00:00:00 1970 From: zhangyanfei Subject: Re: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when loading kvm_intel module Date: Thu, 01 Nov 2012 13:55:04 +0800 Message-ID: <50920EB8.3020400@cn.fujitsu.com> References: <50909B55.2070901@cn.fujitsu.com> <50909C35.9080702@cn.fujitsu.com> <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Cc: "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "x86@kernel.org" , "kexec@lists.infradead.org" , Avi Kivity , Marcelo Tosatti To: "Hatayama, Daisuke" Return-path: In-Reply-To: <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 于 2012年10月31日 17:01, Hatayama, Daisuke 写道: > > >> -----Original Message----- >> From: kexec-bounces@lists.infradead.org >> [mailto:kexec-bounces@lists.infradead.org] On Behalf Of zhangyanfei >> Sent: Wednesday, October 31, 2012 12:34 PM >> To: x86@kernel.org; kexec@lists.infradead.org; Avi Kivity; Marcelo >> Tosatti >> Cc: linux-kernel@vger.kernel.org; kvm@vger.kernel.org >> Subject: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when >> loading kvm_intel module >> >> Signed-off-by: Zhang Yanfei > > [...] > >> @@ -7230,6 +7231,10 @@ static int __init vmx_init(void) >> if (r) >> goto out3; >> >> +#ifdef CONFIG_KEXEC >> + crash_clear_loaded_vmcss = vmclear_local_loaded_vmcss; >> +#endif >> + > > Assignment here cannot cover the case where NMI is initiated after VMX is on in kvm_init and before vmclear_local_loaded_vmcss is assigned, though rare but can happen. > By saying "VMX is on in kvm init", you mean kvm_init enables the VMX feature in the logical processor? No, only there is a vcpu to be created, kvm will enable the VMX feature. I think there is no difference with this assignment before or after kvm_init because the vmcs linked list must be empty before vmx_init is finished. Thanks Zhang Yanfei > What does happen if calling vmclear_local_loaded_vmcss before kvm_init? I think it no problem since the list is initially empty. > >> vmx_disable_intercept_for_msr(MSR_FS_BASE, false); >> vmx_disable_intercept_for_msr(MSR_GS_BASE, false); >> vmx_disable_intercept_for_msr(MSR_KERNEL_GS_BASE, true); >> @@ -7265,6 +7270,10 @@ static void __exit vmx_exit(void) >> free_page((unsigned long)vmx_io_bitmap_b); >> free_page((unsigned long)vmx_io_bitmap_a); >> >> +#ifdef CONFIG_KEXEC >> + crash_clear_loaded_vmcss = NULL; >> +#endif >> + >> kvm_exit(); >> } > > Also, this is converse to the above. > > Thanks. > HATAYAMA, Daisuke > >