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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	paulus@samba.org, mpe@ellerman.id.au, npiggin@gmail.com,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	kvm-ppc@vger.kernel.org
Subject: Re: [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest
Date: Mon, 11 Feb 2019 11:30:54 +1100	[thread overview]
Message-ID: <c2d6938902656f2829be8077c656cee9235c21b1.camel@kernel.crashing.org> (raw)
In-Reply-To: <2ed8efb9-5cd4-31bf-6c7b-501b9d1925e6@ilande.co.uk>

On Fri, 2019-02-08 at 14:51 +0000, Mark Cave-Ayland wrote:
> 
> Indeed, but there are still some questions to be asked here:
> 
> 1) Why were these bits removed from the original bitmask in the first place without
> it being documented in the commit message?
> 
> 2) Is this the right fix? I'm told that MacOS guests already run without this patch
> on a G5 under 64-bit KVM-PR which may suggest that this is a workaround for another
> bug elsewhere in the 32-bit powerpc code.
> 
> 
> If you think that these points don't matter, then I'm happy to resubmit the patch
> as-is based upon your comments above.

We should write a test case to verify that FE0/FE1 are properly
preserved/context-switched etc... I bet if we accidentally wiped them,
we wouldn't notice 99.9% of the time.

Cheers,
Ben.


WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>,
	Christophe Leroy <christophe.leroy@c-s.fr>,
	paulus@samba.org, mpe@ellerman.id.au, npiggin@gmail.com,
	linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org,
	kvm-ppc@vger.kernel.org
Subject: Re: [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest
Date: Mon, 11 Feb 2019 00:30:54 +0000	[thread overview]
Message-ID: <c2d6938902656f2829be8077c656cee9235c21b1.camel@kernel.crashing.org> (raw)
In-Reply-To: <2ed8efb9-5cd4-31bf-6c7b-501b9d1925e6@ilande.co.uk>

On Fri, 2019-02-08 at 14:51 +0000, Mark Cave-Ayland wrote:
> 
> Indeed, but there are still some questions to be asked here:
> 
> 1) Why were these bits removed from the original bitmask in the first place without
> it being documented in the commit message?
> 
> 2) Is this the right fix? I'm told that MacOS guests already run without this patch
> on a G5 under 64-bit KVM-PR which may suggest that this is a workaround for another
> bug elsewhere in the 32-bit powerpc code.
> 
> 
> If you think that these points don't matter, then I'm happy to resubmit the patch
> as-is based upon your comments above.

We should write a test case to verify that FE0/FE1 are properly
preserved/context-switched etc... I bet if we accidentally wiped them,
we wouldn't notice 99.9% of the time.

Cheers,
Ben.

  reply	other threads:[~2019-02-11  1:20 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08 14:33 [PATCH] powerpc: fix 32-bit KVM-PR lockup and panic with MacOS guest Mark Cave-Ayland
2019-02-08 14:33 ` Mark Cave-Ayland
2019-02-08 14:45 ` Christophe Leroy
2019-02-08 14:45   ` Christophe Leroy
2019-02-08 14:51   ` Mark Cave-Ayland
2019-02-08 14:51     ` Mark Cave-Ayland
2019-02-11  0:30     ` Benjamin Herrenschmidt [this message]
2019-02-11  0:30       ` Benjamin Herrenschmidt
2019-02-11 21:39       ` Mark Cave-Ayland
2019-02-19  4:55         ` Michael Ellerman
2019-02-19  4:55           ` Michael Ellerman
2019-02-19  8:15           ` Mark Cave-Ayland
2019-02-19  4:20     ` Michael Ellerman
2019-02-19  4:20       ` Michael Ellerman
2019-02-19  7:55       ` Mark Cave-Ayland
2019-02-20 12:41         ` Michael Ellerman
2019-02-20 12:41           ` Michael Ellerman
2019-02-19 19:31 ` Cameron Kaiser
2019-02-22  9:47 ` Michael Ellerman
2019-02-22  9:47   ` Michael Ellerman

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