Subject: Re: [PATCH V4] POWERPC: BOOK3S: KVM: Use the saved dar value and generic make_dsisr

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Tue, 06 May 2014 19:42:28 +0530

Alexander Graf <[email-masked]> writes:

> On 06.05.14 02:41, Paul Mackerras wrote:
>> On Mon, May 05, 2014 at 01:19:30PM +0200, Alexander Graf wrote:
>>> On 05/04/2014 07:21 PM, Aneesh Kumar K.V wrote:
>>>> +#ifdef CONFIG_PPC_BOOK3S_64
>>>> +	return vcpu->arch.fault_dar;
>>> How about PA6T and G5s?
>> G5 sets DAR on an alignment interrupt.
>>
>> As for PA6T, I don't know for sure, but if it doesn't, ordinary
>> alignment interrupts wouldn't be handled properly, since the code in
>> arch/powerpc/kernel/align.c assumes DAR contains the address being
>> accessed on all PowerPC CPUs.
>
> Now that's a good point. If we simply behave like Linux, I'm fine. This 
> definitely deserves a comment on the #ifdef in the code.

How about ?

#ifdef CONFIG_PPC_BOOK3S_64
	/*
	 * Linux always expect a valid  dar as per alignment
	 * interrupt handling code (fix_alignment()). Don't compute the dar
	 * value here, instead used the saved dar value. Right now we restrict
	 * this only for BOOK3S-64.
	 */
	return vcpu->arch.fault_dar;
#else

-aneesh