From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [PATCH v3 2/2] KVM: make crash_clear_loaded_vmcss valid when loading kvm_intel module Date: Tue, 13 Nov 2012 19:22:03 -0200 Message-ID: <20121113212203.GA26386@amt.cnet> References: <50909B55.2070901@cn.fujitsu.com> <50909C35.9080702@cn.fujitsu.com> <33710E6CAA200E4583255F4FB666C4E20AACCA2F@G01JPEXMBYT03> <50920EB8.3020400@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: "Hatayama, Daisuke" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "x86@kernel.org" , "kexec@lists.infradead.org" , Avi Kivity To: zhangyanfei Return-path: Content-Disposition: inline In-Reply-To: <50920EB8.3020400@cn.fujitsu.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Nov 01, 2012 at 01:55:04PM +0800, zhangyanfei wrote: > =E4=BA=8E 2012=E5=B9=B410=E6=9C=8831=E6=97=A5 17:01, Hatayama, Daisuk= e =E5=86=99=E9=81=93: > >=20 > >=20 > >> -----Original Message----- > >> From: kexec-bounces@lists.infradead.org > >> [mailto:kexec-bounces@lists.infradead.org] On Behalf Of zhangyanfe= i > >> 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 w= hen > >> loading kvm_intel module > >> > >> Signed-off-by: Zhang Yanfei > >=20 > > [...] > >=20 > >> @@ -7230,6 +7231,10 @@ static int __init vmx_init(void) > >> if (r) > >> goto out3; > >> > >> +#ifdef CONFIG_KEXEC > >> + crash_clear_loaded_vmcss =3D vmclear_local_loaded_vmcss; > >> +#endif > >> + > >=20 > > 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. > >=20 >=20 > 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 featu= re. >=20 > I think there is no difference with this assignment before or after k= vm_init because the vmcs linked > list must be empty before vmx_init is finished. The list is not initialized before hardware_enable(), though. Should move the assignment after that. Also, it is possible that the loaded_vmcss_on_cpu list is being modifie= d _while_ crash executes say via NMI, correct? If that is the case, bette= r flag that the list is under manipulation so the vmclear can be skipped. > Thanks > Zhang Yanfei >=20 > > What does happen if calling vmclear_local_loaded_vmcss before kvm_i= nit? I think it no problem since the list is initially empty. > >=20 > >> 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 =3D NULL; > >> +#endif > >> + > >> kvm_exit(); > >> } > >=20 > > Also, this is converse to the above. > >=20 > > Thanks. > > HATAYAMA, Daisuke > >=20 > >=20 >=20 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html