From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Date: Thu, 20 Mar 2008 08:32:23 +0000
Subject: Re: [kvm-ppc-devel] guest panic fixed
Message-Id: <47E22117.9080603@linux.vnet.ibm.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <1205969120.11366.67.camel@basalt>
In-Reply-To: <1205969120.11366.67.camel@basalt>
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To: kvm-ppc@vger.kernel.org

Hollis Blanchard wrote:
> Thanks to some excellent debugging by Christian, we found the cause of
> our annoying guest panics. We had not implemented exception priorities
> (my bad), so a userspace ITLB miss was being delivered immediately after
> entry to the decrementer interrupt vector. Patch follows,
> http://penguinppc.org/~hollisb/kvm/ updated.
>=20
> NFS root with virtio-net still doesn't work for me, but it doesn't
> crash. :)
>=20
> @@ -65,12 +68,14 @@ extern void kvmppc_44x_tlb_trace(int act
>=20
>  static inline void kvmppc_queue_exception(struct kvm_vcpu *vcpu, int exc=
eption)
>  {
> -	set_bit(exception, &vcpu->arch.pending_exceptions);
> +	unsigned int priority =3D exception_priority[exception];
> +	set_bit(priority, &vcpu->arch.pending_exceptions);

saves a line and a local var on irq path (well the compiler might optimize =
that anyway)
	set_bit(exception_priority[exception], &vcpu->arch.pending_exceptions);

>  }
>=20
>  static inline void kvmppc_clear_exception(struct kvm_vcpu *vcpu, int exc=
eption)
>  {
> -	clear_bit(exception, &vcpu->arch.pending_exceptions);
> +	unsigned int priority =3D exception_priority[exception];
> +	clear_bit(priority, &vcpu->arch.pending_exceptions);

same as above

>  }
>=20
>  static inline void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 new_msr)
=20


--=20

Gr=FCsse / regards,=20
Christian Ehrhardt
IBM Linux Technology Center, Open Virtualization

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