From: vladimir.murzin@arm.com (Vladimir Murzin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support
Date: Wed, 7 Sep 2016 11:48:52 +0100 [thread overview]
Message-ID: <57CFF094.5000704@arm.com> (raw)
In-Reply-To: <20160906165527.GG23592@cbox>
On 06/09/16 17:55, Christoffer Dall wrote:
> On Tue, Sep 06, 2016 at 02:23:16PM +0100, Vladimir Murzin wrote:
>>
>> Sorry, missed this one
>>
>> On 05/09/16 12:29, Christoffer Dall wrote:
>>>>
>>>>> +static bool __hyp_text __has_useable_gicv3_cpuif(void)
>>>>> +{
>>>>> + if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28))
>>> Do we have a define for bit 28 we could use?
>>
>> I'll check it.
>>
>>>
>>> Does this actually work on all v7 boards? The v7 ARM ARM seems to state
>>> that this bitfield is Reserved, UNK. Does that somehow mean 'is going
>>> to be zero'?
>>
>> It is how v7ARM ARM I have defines UNK
>>
>> An abbreviation indicating that software must treat a field as
>> containing an UNKNOWN value. Hardware must implement the bit as read as
>> 0, or all 0s for a bit field. Software must not rely on the field
>> reading as zero.
>>
>> It seems goes under 'is going to be zero' case, no?
>>
> The last sentence is disturbing to me, and feels slightly contradicting
> itself. Reading the UNKNOWN description doesn't help much either.
>
> Perhaps you can ask around internally and figure out what the precise
> answer to this is?
Since it is kind of implementation dependant thing the precise answer
from here hardly help, IMO. We still have non-zero chance to see
something scary.
OTOH, why do we care of all v7 boards if none of them have
CONFIG_ARM_GIC_V3 defined?
Cheers
Vladimir
>
> Thanks,
> -Christoffer
>
>
next prev parent reply other threads:[~2016-09-07 10:48 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 10:46 [PATCH v2 0/7] ARM: KVM: Support for vgic-v3 Vladimir Murzin
2016-08-16 10:46 ` [PATCH v2 1/7] arm64: KVM: Move GIC accessors to arch_gicv3.h Vladimir Murzin
2016-09-05 11:28 ` Christoffer Dall
2016-09-06 12:33 ` Vladimir Murzin
2016-08-16 10:46 ` [PATCH v2 2/7] arm64: KVM: Move vgic-v3 save/restore to virt/kvm/arm/hyp Vladimir Murzin
2016-08-16 10:46 ` [PATCH v2 3/7] KVM: arm: vgic-new: improve compatibility with 32-bit Vladimir Murzin
2016-09-05 11:29 ` Christoffer Dall
2016-09-06 12:41 ` Vladimir Murzin
2016-09-06 13:22 ` Christoffer Dall
2016-09-06 13:54 ` Vladimir Murzin
2016-09-06 16:31 ` Christoffer Dall
2016-09-07 9:06 ` Vladimir Murzin
2016-09-07 9:43 ` Christoffer Dall
2016-08-16 10:46 ` [PATCH v2 4/7] ARM: update MPIDR accessors macro Vladimir Murzin
2016-09-05 11:29 ` Christoffer Dall
2016-09-06 12:42 ` Vladimir Murzin
2016-08-16 10:46 ` [PATCH v2 5/7] ARM: move system register accessors to asm/cp15.h Vladimir Murzin
2016-09-05 11:29 ` Christoffer Dall
2016-09-06 13:05 ` Vladimir Murzin
2016-09-06 16:34 ` Christoffer Dall
2016-08-16 10:46 ` [PATCH v2 6/7] ARM: KVM: Get ready to use vgic-v3 Vladimir Murzin
2016-09-05 11:29 ` Christoffer Dall
2016-09-06 13:12 ` Vladimir Murzin
2016-09-06 16:49 ` Christoffer Dall
2016-08-16 10:46 ` [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support Vladimir Murzin
2016-09-05 11:29 ` Christoffer Dall
2016-09-06 13:08 ` Marc Zyngier
2016-09-06 13:18 ` Vladimir Murzin
2016-09-06 16:52 ` Christoffer Dall
2016-09-06 13:23 ` Vladimir Murzin
2016-09-06 16:55 ` Christoffer Dall
2016-09-07 10:48 ` Vladimir Murzin [this message]
2016-09-07 12:58 ` Christoffer Dall
2016-09-07 14:20 ` Peter Maydell
2016-09-07 14:47 ` Christoffer Dall
2016-09-05 11:28 ` [PATCH v2 0/7] ARM: KVM: Support for vgic-v3 Christoffer Dall
2016-09-06 12:32 ` Vladimir Murzin
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