linux-kernel - Re: [PATCH] [2/2] KVM: Add VT-x machine check support

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Date:	Thu, 04 Jun 2009 14:48:17 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Andi Kleen <andi@...stfloor.org>
CC:	ying.huang@...el.com, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] [2/2] KVM: Add VT-x machine check support

Andi Kleen wrote:
> [Avi could you please still consider this patch for your 2.6.31 patchqueue?
> It's fairly simple, but important to handle memory errors in guests]
>   

Oh yes, and it'll be needed for -stable.  IIUC, right now a machine 
check is trapped by the guest, so the guest is killed instead of the host?

> +/*
> + * Trigger machine check on the host. We assume all the MSRs are already set up
> + * by the CPU and that we still run on the same CPU as the MCE occurred on.
> + * We pass a fake environment to the machine check handler because we want
> + * the guest to be always treated like user space, no matter what context
> + * it used internally.
> + */
>   

This assumption is incorrect.  This code is executed after preemption 
has been enabled, and we may have even slept before reaching it.

NMI suffers from the same issue, see vmx_complete_interrupts().  You 
could handle it the same way.

> @@ -3150,6 +3171,7 @@
>  	[EXIT_REASON_WBINVD]                  = handle_wbinvd,
>  	[EXIT_REASON_TASK_SWITCH]             = handle_task_switch,
>  	[EXIT_REASON_EPT_VIOLATION]	      = handle_ept_violation,
> +	[EXIT_REASON_MACHINE_CHECK]	      = handle_machine_check,
>  };
>  
>  static const int kvm_vmx_max_exit_handlers =
>   

We get both an explicit EXIT_REASON and an exception?

-- 
error compiling committee.c: too many arguments to function

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