From: Daniel Thompson <daniel.thompson@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>,
Auger Eric <eric.auger@redhat.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
Christoffer Dall <christoffer.dall@linaro.org>
Cc: Andrew Jones <drjones@redhat.com>,
Robert Richter <robert.richter@caviumnetworks.com>
Subject: Re: v4.9-rc1 fails booting as a guest on ARM64 Cavium ThunderX
Date: Fri, 21 Oct 2016 11:40:50 +0100 [thread overview]
Message-ID: <5e2c7786-1d03-874c-9ed3-13cd7be0fbf5@linaro.org> (raw)
In-Reply-To: <de2acaca-f694-be1a-5d2c-93fcf3b25011@arm.com>
On 21/10/16 09:45, Marc Zyngier wrote:
> +Robert
>
> On 21/10/16 08:01, Auger Eric wrote:
>> Hi,
>>
>> I am not able to boot 4.9-rc1 as a guest on Cavium ThunderX (dt and acpi
>> mode). Bisecting the guest shows that the problem shows up at
>>
>> 91ef84428a86b75a52e15c6fe4f56b446ba75f93
>> irqchip/gic-v3: Reset BPR during initialization
>>
>> If I remove the write to the ICC_BPR1_EL1 register on guest, the VM boots.
>
> That's very odd. A ICC_BPR1_EL1 access when HCR_EL2.IMO is set only
> affects ICH_VMCR_EL2.VBPR1. It is not trapped, since we don't set
> ICH_HCR_EL2.TALL1. It is a very boring sysreg!
>
> So from a pure architectural point of view, I don't see how this can
> fail. I've just run the same configuration on my Freescale board (GICv3
> as well), and can't see any issue at all.
Wow. Of all the patches I written for arm64 this was not the one I
regarded as especially risky [at least when compared to the others ;-)].
Of course it does rely on writing a zero being "an attempt to program
the binary point field to a value less than the reset value" and "sets
the field to the reset value." and from a silicon validation point of
view that might be regarded as a interesting corner case...
Daniel.
prev parent reply other threads:[~2016-10-21 10:40 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-21 7:01 v4.9-rc1 fails booting as a guest on ARM64 Cavium ThunderX Auger Eric
2016-10-21 8:45 ` Marc Zyngier
2016-10-21 9:05 ` Auger Eric
2016-10-21 9:40 ` Marc Zyngier
2016-10-21 9:46 ` Auger Eric
2016-10-21 11:49 ` Andrew Jones
2016-10-21 11:57 ` Peter Maydell
2016-10-21 12:07 ` Andrew Jones
2016-10-21 12:52 ` Marc Zyngier
2016-10-21 12:58 ` Peter Maydell
2016-10-21 13:20 ` Marc Zyngier
2016-10-21 13:06 ` Andrew Jones
2016-10-21 13:47 ` Marc Zyngier
2016-10-21 16:34 ` Robert Richter
2016-10-26 7:18 ` Robert Richter
2016-10-26 7:39 ` Marc Zyngier
2016-11-03 18:01 ` Robert Richter
2016-11-04 13:30 ` Auger Eric
2016-10-21 10:40 ` Daniel Thompson [this message]
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