linux-kernel - Re: [RFC 1/8]KVM: fix bugs in kvm sched integration patch

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Message-ID: <46A48713.9080404@qumranet.com>
Date:	Mon, 23 Jul 2007 13:46:43 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	Shaohua Li <shaohua.li@...el.com>
CC:	kvm-devel <kvm-devel@...ts.sourceforge.net>,
	lkml <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC 1/8]KVM: fix bugs in kvm sched integration patch

Shaohua Li wrote:
> fix some bugs in kvm-sch patch.
>   

There is now a 'preempt-hooks' branch on kvm.git with the preempt-hooks 
work.  I'll continually update and rebase it against master.

> 1. vmcs_readl/vmcs_writel are called with preempt enabled
>   

Why is that bad?

> 2. preempt_count check doesn't make sense with preempt disabled
>   

That is already fixed in the branch.

> 3. vmx_cpu_run doesn't handle error correctly and kvm_mmu_reload might
> sleep with mutex changes, so I move it above.
>   

Yes.

> @@ -2001,6 +1997,10 @@ preempted:
>  		kvm_guest_debug_pre(vcpu);
>  
>  again:
> +	r = kvm_mmu_reload(vcpu);
> +	if (unlikely(r))
> +		goto out;
> +
>  	preempt_disable();
>  
>  	if (!vcpu->mmio_read_completed)
> @@ -2009,10 +2009,6 @@ again:
>  	vmx_save_host_state(vcpu);
>  	kvm_load_guest_fpu(vcpu);
>  
> -	r = kvm_mmu_reload(vcpu);
> -	if (unlikely(r))
> -		goto out;
> -
>  	/*
>  	 * Loading guest fpu may have cleared host cr0.ts
>  	 */
>   

I'll add this (and the spinlock->mutex conversion) to the branch.

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

-
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