On Thu, Nov 01, 2012 at 01:55:04PM +0800, zhangyanfei wrote: > ? 2012?10?31? 17:01, Hatayama, Daisuke ??: > > > > > >> -----Original Message----- > >> From: kexec-bounces at lists.infradead.org > >> [mailto:kexec-bounces at lists.infradead.org] On Behalf Of zhangyanfei > >> Sent: Wednesday, October 31, 2012 12:34 PM > >> To: x86 at kernel.org; kexec at lists.infradead.org; Avi Kivity; Marcelo > >> Tosatti > >> Cc: linux-kernel at vger.kernel.org; kvm at 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 <zhangyanfei at cn.fujitsu.com> > > > > [...] > > > >> @@ -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. 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 modified _while_ crash executes say via NMI, correct? If that is the case, better flag that the list is under manipulation so the vmclear can be skipped. > 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 > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo at vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
