linux-kernel - Re: [PATCH v9 1/2] x86/kexec: VMCLEAR VMCSs loaded on all cpus if necessary

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Message-ID: <20121127121847.GU25516@redhat.com>
Date:	Tue, 27 Nov 2012 14:18:47 +0200
From:	Gleb Natapov <gleb@...hat.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	"x86@...nel.org" <x86@...nel.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	"kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 1/2] x86/kexec: VMCLEAR VMCSs loaded on all cpus if
 necessary

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@...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.
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