Re: [kvm-devel] Starting a VM reboots my machine

[Avi K. <av...@qu...>]

Andrea Arcangeli wrote:
> On Sun, Nov 04, 2007 at 08:15:26AM -0800, Alexey Eremenko wrote:
>   
>> Cam: KVM-AMD is unstable now, unless you're a developer, I would suggest you to downgrade to KVM-36, which was the latest AMD-friendly version. We're working on a fix.
>>
>> Dor: kvm-amd crashes host, without leaving any netconsole messages.
>>     
>
> With x2 stepping G1 and with the below two fixes applied on top of kvm
> and kvm-userland at least the host is certainly solid for me (the
> opensuse 10.3 guest seems ok too). The x86 hack is mandatory with last
> git kvm kernel, without it it's an immediate crash.
>
> Signed-off-by: Andrea Arcangeli <an...@su...>
>
> diff --git a/kernel/Makefile b/kernel/Makefile
> index b78c81a..68f6929 100644
> --- a/kernel/Makefile
> +++ b/kernel/Makefile
> @@ -32,6 +32,7 @@ sync:
>  	$(call hack, mmu.c)
>  	$(call hack, vmx.c)
>  	$(call hack, svm.c)
> +	$(call hack, x86.c)
>  
>  install:
>  	mkdir -p $(DESTDIR)/$(INSTALLDIR)
>
>
>   

This one's obviously correct, will apply...

> Signed-off-by: Andrea Arcangeli <an...@su...>
>
> index 9584d0f..95a3489 100644
> --- a/drivers/kvm/svm.c
> +++ b/drivers/kvm/svm.c
> @@ -1459,11 +1459,6 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
>  
>  	local_irq_enable();
>  
> -	vcpu->guest_mode = 1;
> -	if (vcpu->requests)
> -		if (test_and_clear_bit(KVM_TLB_FLUSH, &vcpu->requests))
> -		    svm_flush_tlb(vcpu);
> -
>  	asm volatile (
>  #ifdef CONFIG_X86_64
>  		"push %%rbp; \n\t"
>
>   

Against which kvm is that? It isn't 2.6.24-rc, or kvm.git, or 2.6.23?

Anyway, removing guest tlb flushing won't be good for the guest.

-- 
Any sufficiently difficult bug is indistinguishable from a feature.