From: marc.zyngier@arm•com (Marc Zyngier)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 03/18] arm64: boot protocol documentation update for GICv3
Date: Wed, 26 Feb 2014 15:59:31 +0000 [thread overview]
Message-ID: <530E0F63.3070007@arm.com> (raw)
In-Reply-To: <20140226153142.GA12882@mudshark.cambridge.arm.com>
On 26/02/14 15:31, Will Deacon wrote:
> On Wed, Feb 26, 2014 at 02:37:00PM +0000, Marc Zyngier wrote:
>> On 25/02/14 18:06, Will Deacon wrote:
>>> On Wed, Feb 05, 2014 at 01:30:35PM +0000, Marc Zyngier wrote:
>>>> Linux has some requirements that must be satisfied in order to boot
>>>> on a system built with a GICv3.
>>>>
>>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm•com>
>>>> ---
>>>> Documentation/arm64/booting.txt | 7 +++++++
>>>> 1 file changed, 7 insertions(+)
>>>>
>>>> diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt
>>>> index a9691cc..4a02ebd 100644
>>>> --- a/Documentation/arm64/booting.txt
>>>> +++ b/Documentation/arm64/booting.txt
>>>> @@ -131,6 +131,13 @@ Before jumping into the kernel, the following conditions must be met:
>>>> the kernel image will be entered must be initialised by software at a
>>>> higher exception level to prevent execution in an UNKNOWN state.
>>>>
>>>> + For systems with a GICv3 interrupt controller, it is expected that:
>>>> + - ID_AA64PFR0_EL1.GIC (bits [27:24]) must have the value 0b0001
>>>
>>> Since ID_AA64PFR0_EL1 is read-only at all exception levels, I don't see the
>>> value of this statement.
>>
>> Think virtualization. A hypervisor can control reads of ID_AA64PFR0_EL1
>> by setting HCR_EL2.TID3, and report whatever it wants.
>
> Sure, but it seems unreasonable to me that we require a hypervisor to tell a
> guest about GICv3 if the system happens to have one. What if it wants to
> emulate a GICv2? In other words, requiring this in booting.txt seems
> superflous.
The hypervisor can perfectly mask out the GICv3 feature if it wants to.
The point I'm trying to make here is that if a guest is expected to be
able to use the GICv3 system registers, then ID_AA64PFR0_EL1 should
report so.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2014-02-26 15:59 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-05 13:30 [PATCH 00/18] arm64: GICv3 support Marc Zyngier
2014-02-05 13:30 ` [PATCH 01/18] arm64: initial support for GICv3 Marc Zyngier
2014-02-07 8:59 ` Arnab Basu
2014-02-07 13:52 ` Christopher Covington
2014-02-13 15:28 ` Marc Zyngier
2014-02-17 1:19 ` Christoffer Dall
2014-02-17 16:41 ` Marc Zyngier
2014-02-17 18:10 ` Christoffer Dall
2014-02-25 18:06 ` Will Deacon
2014-02-26 12:53 ` Marc Zyngier
2014-02-27 12:07 ` Will Deacon
2014-03-15 15:22 ` Radha Mohan
2014-02-05 13:30 ` [PATCH 02/18] arm64: GICv3 device tree binding documentation Marc Zyngier
2014-02-07 5:41 ` Arnab Basu
2014-02-13 12:59 ` Marc Zyngier
2014-02-13 13:27 ` Rob Herring
2014-02-13 13:26 ` Rob Herring
2014-02-13 14:00 ` Marc Zyngier
2014-02-17 1:21 ` Christoffer Dall
2014-02-17 16:57 ` Marc Zyngier
2014-02-05 13:30 ` [PATCH 03/18] arm64: boot protocol documentation update for GICv3 Marc Zyngier
2014-02-05 15:03 ` Catalin Marinas
2014-02-25 18:06 ` Will Deacon
2014-02-26 14:37 ` Marc Zyngier
2014-02-26 15:31 ` Will Deacon
2014-02-26 15:59 ` Marc Zyngier [this message]
2014-02-26 16:01 ` Will Deacon
2014-02-05 13:30 ` [PATCH 04/18] KVM: arm/arm64: vgic: move GICv2 registers to their own structure Marc Zyngier
2014-03-04 3:32 ` Christoffer Dall
2014-02-05 13:30 ` [PATCH 05/18] KVM: ARM: vgic: introduce vgic_ops and LR manipulation primitives Marc Zyngier
2014-02-05 13:30 ` [PATCH 06/18] KVM: ARM: vgic: abstract access to the ELRSR bitmap Marc Zyngier
2014-02-05 13:30 ` [PATCH 07/18] KVM: ARM: vgic: abstract EISR bitmap access Marc Zyngier
2014-02-05 13:30 ` [PATCH 08/18] KVM: ARM: vgic: abstract MISR decoding Marc Zyngier
2014-02-05 13:30 ` [PATCH 09/18] KVM: ARM: vgic: move underflow handling to vgic_ops Marc Zyngier
2014-02-05 13:30 ` [PATCH 10/18] KVM: ARM: vgic: abstract VMCR access Marc Zyngier
2014-02-05 13:30 ` [PATCH 11/18] KVM: ARM: vgic: introduce vgic_enable Marc Zyngier
2014-02-05 13:30 ` [PATCH 12/18] KVM: ARM: introduce vgic_params structure Marc Zyngier
2014-02-05 13:30 ` [PATCH 13/18] KVM: ARM: vgic: split GICv2 backend from the main vgic code Marc Zyngier
2014-02-05 13:30 ` [PATCH 14/18] arm64: KVM: remove __kvm_hyp_code_{start, end} from hyp.S Marc Zyngier
2014-02-05 13:30 ` [PATCH 15/18] arm64: KVM: split GICv2 world switch from hyp code Marc Zyngier
2014-02-25 18:07 ` Will Deacon
2014-02-05 13:30 ` [PATCH 16/18] arm64: KVM: move hcr_el2 setting into vgic-v2-switch.S Marc Zyngier
2014-02-05 13:30 ` [PATCH 17/18] KVM: ARM: vgic: add the GICv3 backend Marc Zyngier
2014-02-25 18:07 ` Will Deacon
2014-02-26 18:18 ` Marc Zyngier
2014-02-27 12:12 ` Will Deacon
2014-02-05 13:30 ` [PATCH 18/18] arm64: KVM: vgic: add GICv3 world switch Marc Zyngier
2014-02-25 18:08 ` Will Deacon
2014-02-26 18:06 ` Marc Zyngier
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