linux-kernel - Re: [PATCH -v3] KVM: Add VT-x machine check support

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Date:	Mon, 08 Jun 2009 11:48:13 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Huang Ying <ying.huang@...el.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH -v3] KVM: Add VT-x machine check support

Huang Ying wrote:
> From: Andi Kleen <ak@...ux.intel.com>
>
> VT-x needs an explicit MC vector intercept to handle machine checks in the 
> hyper visor.
>
> It also has a special option to catch machine checks that happen
> during VT entry.
>
> Do these interceptions and forward them to the Linux machine check
> handler. Make it always look like user space is interrupted because
> the machine check handler treats kernel/user space differently.
>
> Thanks to Jiang Yunhong for help and testing.
>
>   

Noticed an additional problem.  See below.

>  static int handle_exception(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  {
>  	struct vcpu_vmx *vmx = to_vmx(vcpu);
> @@ -2616,6 +2640,10 @@ static int handle_exception(struct kvm_v
>  	vect_info = vmx->idt_vectoring_info;
>  	intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
>  
> +	ex_no = intr_info & INTR_INFO_VECTOR_MASK;
> +	if (ex_no == MC_VECTOR)
> +		return handle_machine_check(vcpu, kvm_run);
> +
>   

It isn't sufficient to check the vector number; you also need to check 
the interrupt type.  See for example is_page_fault() and is_no_device().

I suggest you add an is_machine_check() along similar lines.  Later we 
can collapse all those functions to use a single helper.


> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -382,6 +382,8 @@ struct kvm_vcpu_arch {
>  	u64 mcg_status;
>  	u64 mcg_ctl;
>  	u64 *mce_banks;
> +
> +	u32 exit_reason;
>  };
>   

Please move this into struct vcpu_vmx.

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

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