Re: [PATCH v9 1/2] x86/kexec: VMCLEAR VMCSs loaded on all cpus ifnecessary

From: Gleb Natapov
Date: Mon Dec 03 2012 - 08:46:52 EST


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@xxxxxxxxxxxxxx>
> > ---
> > 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.
> --
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--
Gleb.
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