| Message ID | 50B432CA.70804@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Eric, can you ACK it? On Tue, Nov 27, 2012 at 11:26:02AM +0800, Zhang Yanfei wrote: > This patch provides a way to VMCLEAR VMCSs related to guests > on all cpus before executing the VMXOFF when doing kdump. This > is used to ensure the VMCSs in the vmcore updated and > non-corrupted. > > Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> > --- > arch/x86/include/asm/kexec.h | 2 ++ > arch/x86/kernel/crash.c | 25 +++++++++++++++++++++++++ > 2 files changed, 27 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h > index 317ff17..28feeba 100644 > --- a/arch/x86/include/asm/kexec.h > +++ b/arch/x86/include/asm/kexec.h > @@ -163,6 +163,8 @@ struct kimage_arch { > }; > #endif > > +extern void (*crash_vmclear_loaded_vmcss)(void); > + > #endif /* __ASSEMBLY__ */ > > #endif /* _ASM_X86_KEXEC_H */ > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > index 13ad899..4a2a12f 100644 > --- a/arch/x86/kernel/crash.c > +++ b/arch/x86/kernel/crash.c > @@ -16,6 +16,7 @@ > #include <linux/delay.h> > #include <linux/elf.h> > #include <linux/elfcore.h> > +#include <linux/module.h> > > #include <asm/processor.h> > #include <asm/hardirq.h> > @@ -29,6 +30,20 @@ > #include <asm/virtext.h> > > int in_crash_kexec; > + > +/* > + * This is used to VMCLEAR all VMCSs loaded on the > + * processor. And when loading kvm_intel module, the > + * callback function pointer will be assigned. > + */ > +void (*crash_vmclear_loaded_vmcss)(void) = NULL; > +EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); > + > +static inline void cpu_emergency_vmclear_loaded_vmcss(void) > +{ > + if (crash_vmclear_loaded_vmcss) > + crash_vmclear_loaded_vmcss(); > +} > > #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) > > @@ -46,6 +61,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) > #endif > crash_save_cpu(regs, cpu); > > + /* > + * VMCLEAR VMCSs loaded on all cpus if needed. > + */ > + cpu_emergency_vmclear_loaded_vmcss(); > + > /* Disable VMX or SVM if needed. > * > * We need to disable virtualization on all CPUs. > @@ -88,6 +108,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs) > > kdump_nmi_shootdown_cpus(); > > + /* > + * VMCLEAR VMCSs loaded on this cpu if needed. > + */ > + cpu_emergency_vmclear_loaded_vmcss(); > + > /* Booting kdump kernel with VMX or SVM enabled won't work, > * because (among other limitations) we can't disable paging > * with the virt flags. > -- > 1.7.1 -- Gleb. -- 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
On Tue, Nov 27, 2012 at 02:18:47PM +0200, Gleb Natapov wrote: > Eric, can you ACK it? > Eric, ping. > On Tue, Nov 27, 2012 at 11:26:02AM +0800, Zhang Yanfei wrote: > > This patch provides a way to VMCLEAR VMCSs related to guests > > on all cpus before executing the VMXOFF when doing kdump. This > > is used to ensure the VMCSs in the vmcore updated and > > non-corrupted. > > > > Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> > > --- > > arch/x86/include/asm/kexec.h | 2 ++ > > arch/x86/kernel/crash.c | 25 +++++++++++++++++++++++++ > > 2 files changed, 27 insertions(+), 0 deletions(-) > > > > diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h > > index 317ff17..28feeba 100644 > > --- a/arch/x86/include/asm/kexec.h > > +++ b/arch/x86/include/asm/kexec.h > > @@ -163,6 +163,8 @@ struct kimage_arch { > > }; > > #endif > > > > +extern void (*crash_vmclear_loaded_vmcss)(void); > > + > > #endif /* __ASSEMBLY__ */ > > > > #endif /* _ASM_X86_KEXEC_H */ > > diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c > > index 13ad899..4a2a12f 100644 > > --- a/arch/x86/kernel/crash.c > > +++ b/arch/x86/kernel/crash.c > > @@ -16,6 +16,7 @@ > > #include <linux/delay.h> > > #include <linux/elf.h> > > #include <linux/elfcore.h> > > +#include <linux/module.h> > > > > #include <asm/processor.h> > > #include <asm/hardirq.h> > > @@ -29,6 +30,20 @@ > > #include <asm/virtext.h> > > > > int in_crash_kexec; > > + > > +/* > > + * This is used to VMCLEAR all VMCSs loaded on the > > + * processor. And when loading kvm_intel module, the > > + * callback function pointer will be assigned. > > + */ > > +void (*crash_vmclear_loaded_vmcss)(void) = NULL; > > +EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); > > + > > +static inline void cpu_emergency_vmclear_loaded_vmcss(void) > > +{ > > + if (crash_vmclear_loaded_vmcss) > > + crash_vmclear_loaded_vmcss(); > > +} > > > > #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) > > > > @@ -46,6 +61,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) > > #endif > > crash_save_cpu(regs, cpu); > > > > + /* > > + * VMCLEAR VMCSs loaded on all cpus if needed. > > + */ > > + cpu_emergency_vmclear_loaded_vmcss(); > > + > > /* Disable VMX or SVM if needed. > > * > > * We need to disable virtualization on all CPUs. > > @@ -88,6 +108,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs) > > > > kdump_nmi_shootdown_cpus(); > > > > + /* > > + * VMCLEAR VMCSs loaded on this cpu if needed. > > + */ > > + cpu_emergency_vmclear_loaded_vmcss(); > > + > > /* Booting kdump kernel with VMX or SVM enabled won't work, > > * because (among other limitations) we can't disable paging > > * with the virt flags. > > -- > > 1.7.1 > > -- > Gleb. > -- > 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 -- Gleb. -- 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
Zhang Yanfei <zhangyanfei@cn.fujitsu.com> writes: > This patch provides a way to VMCLEAR VMCSs related to guests > on all cpus before executing the VMXOFF when doing kdump. This > is used to ensure the VMCSs in the vmcore updated and > non-corrupted. Apologies for the delay I have been travelling, and I wanted to at least read through the code. Overall I think this is good but I have one nit, and I see one real problem with this code. > +/* > + * This is used to VMCLEAR all VMCSs loaded on the > + * processor. And when loading kvm_intel module, the > + * callback function pointer will be assigned. > + */ > +void (*crash_vmclear_loaded_vmcss)(void) = NULL; > +EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); > + > +static inline void cpu_emergency_vmclear_loaded_vmcss(void) > +{ > + if (crash_vmclear_loaded_vmcss) > + crash_vmclear_loaded_vmcss(); > +} The nit is the use of emergency instead of crash in the name. The problem is that this is potentially a NULL pointer dereference if kvm-intel is removed. The easist fix would be in your second patch to just make it impossible to unload the kvm-intel module. Otherwise there the deference of crash_vmclear_loaded_vmcss needs to be rcu protected, with a syncrhonize_rcu after the pointer is set to NULL in the unload path. Otherwise I have no objections to this code. Eric -- 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
? 2012?12?05? 04:14, Eric W. Biederman ??: > Zhang Yanfei <zhangyanfei@cn.fujitsu.com> writes: > >> This patch provides a way to VMCLEAR VMCSs related to guests >> on all cpus before executing the VMXOFF when doing kdump. This >> is used to ensure the VMCSs in the vmcore updated and >> non-corrupted. > > Apologies for the delay I have been travelling, and I wanted > to at least read through the code. > > Overall I think this is good but I have one nit, and I see one real > problem with this code. > >> +/* >> + * This is used to VMCLEAR all VMCSs loaded on the >> + * processor. And when loading kvm_intel module, the >> + * callback function pointer will be assigned. >> + */ >> +void (*crash_vmclear_loaded_vmcss)(void) = NULL; >> +EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); >> + >> +static inline void cpu_emergency_vmclear_loaded_vmcss(void) >> +{ >> + if (crash_vmclear_loaded_vmcss) >> + crash_vmclear_loaded_vmcss(); >> +} > > The nit is the use of emergency instead of crash in the name. ok, emergency -> crash > > The problem is that this is potentially a NULL pointer dereference if > kvm-intel is removed. The easist fix would be in your second patch to > just make it impossible to unload the kvm-intel module. Otherwise > there the deference of crash_vmclear_loaded_vmcss needs to be rcu > protected, with a syncrhonize_rcu after the pointer is set to NULL in > the unload path. Ah, thanks for this comment. I think I will use the rcu machanism to solve the problem. > > Otherwise I have no objections to this code. Thanks for your review. I will update the patch and resend it. Thanks Zhang Yanfei -- 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
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h index 317ff17..28feeba 100644 --- a/arch/x86/include/asm/kexec.h +++ b/arch/x86/include/asm/kexec.h @@ -163,6 +163,8 @@ struct kimage_arch { }; #endif +extern void (*crash_vmclear_loaded_vmcss)(void); + #endif /* __ASSEMBLY__ */ #endif /* _ASM_X86_KEXEC_H */ diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c index 13ad899..4a2a12f 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -16,6 +16,7 @@ #include <linux/delay.h> #include <linux/elf.h> #include <linux/elfcore.h> +#include <linux/module.h> #include <asm/processor.h> #include <asm/hardirq.h> @@ -29,6 +30,20 @@ #include <asm/virtext.h> int in_crash_kexec; + +/* + * This is used to VMCLEAR all VMCSs loaded on the + * processor. And when loading kvm_intel module, the + * callback function pointer will be assigned. + */ +void (*crash_vmclear_loaded_vmcss)(void) = NULL; +EXPORT_SYMBOL_GPL(crash_vmclear_loaded_vmcss); + +static inline void cpu_emergency_vmclear_loaded_vmcss(void) +{ + if (crash_vmclear_loaded_vmcss) + crash_vmclear_loaded_vmcss(); +} #if defined(CONFIG_SMP) && defined(CONFIG_X86_LOCAL_APIC) @@ -46,6 +61,11 @@ static void kdump_nmi_callback(int cpu, struct pt_regs *regs) #endif crash_save_cpu(regs, cpu); + /* + * VMCLEAR VMCSs loaded on all cpus if needed. + */ + cpu_emergency_vmclear_loaded_vmcss(); + /* Disable VMX or SVM if needed. * * We need to disable virtualization on all CPUs. @@ -88,6 +108,11 @@ void native_machine_crash_shutdown(struct pt_regs *regs) kdump_nmi_shootdown_cpus(); + /* + * VMCLEAR VMCSs loaded on this cpu if needed. + */ + cpu_emergency_vmclear_loaded_vmcss(); + /* Booting kdump kernel with VMX or SVM enabled won't work, * because (among other limitations) we can't disable paging * with the virt flags.
This patch provides a way to VMCLEAR VMCSs related to guests on all cpus before executing the VMXOFF when doing kdump. This is used to ensure the VMCSs in the vmcore updated and non-corrupted. Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> --- arch/x86/include/asm/kexec.h | 2 ++ arch/x86/kernel/crash.c | 25 +++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 0 deletions(-)