From: James Morse <james.morse@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 4/5] KVM: arm64: Limit the debug architecture to ARMv8.0
Date: Tue, 18 Feb 2020 17:45:14 +0000 [thread overview]
Message-ID: <37f71ccb-2c3c-5c7c-ef26-0dfdaf4e52a3@arm.com> (raw)
In-Reply-To: <20200216185324.32596-5-maz@kernel.org>
Hi Marc,
On 16/02/2020 18:53, Marc Zyngier wrote:
> Let's not pretend we support anything but ARMv8.0 as far as the
> debug architecture is concerned.
(what happens for features that disappeared?)
For v8.0 the 'OS Double Lock' was mandatory. With v8.2 it became optional, and
not-implemented with v8.3.
The guest can see whether its implemented in ID_AA64DFR0_EL1. (and its 32bit friends)
Previously these values would have at least matched, even though KVM implements it as
RAZ/WI (which is the not-implemented behaviour).
Would anyone care that these are inconsistent?
(I've never had a solid grasp of how these debug 'lock' registers are supposed to be used).
Thanks,
James
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 06b2d0dc6c73..43087b50a211 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1094,6 +1094,9 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu,
> FEATURE(ID_AA64ISAR1_GPI));
> break;
> case SYS_ID_AA64DFR0_EL1:
> + /* Limit debug to ARMv8.0 */
> + val &= ~FEATURE(ID_AA64DFR0_DEBUGVER);
> + val |= FIELD_PREP(FEATURE(ID_AA64DFR0_DEBUGVER), 6);
> /* Limit PMU to ARMv8.1 */
> val &= ~FEATURE(ID_AA64DFR0_PMUVER);
> val |= FIELD_PREP(FEATURE(ID_AA64DFR0_PMUVER), 4);
>
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next prev parent reply other threads:[~2020-02-18 17:45 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-16 18:53 [PATCH 0/5] Random debug/PMU fixes for 5.6 Marc Zyngier
2020-02-16 18:53 ` [PATCH 1/5] KVM: arm64: Fix missing RES1 in emulation of DBGBIDR Marc Zyngier
2020-02-18 17:43 ` James Morse
2020-02-18 18:01 ` Robin Murphy
2020-02-18 18:15 ` James Morse
2020-02-16 18:53 ` [PATCH 2/5] KVM: arm64: Refactor filtering of ID registers Marc Zyngier
2020-02-20 14:12 ` Andre Przywara
2020-02-16 18:53 ` [PATCH 3/5] kvm: arm64: Limit PMU version to ARMv8.1 Marc Zyngier
2020-02-18 17:43 ` James Morse
2020-02-19 9:46 ` Marc Zyngier
2020-02-19 10:18 ` James Morse
2020-02-19 11:14 ` Marc Zyngier
2020-02-16 18:53 ` [PATCH 4/5] KVM: arm64: Limit the debug architecture to ARMv8.0 Marc Zyngier
2020-02-18 17:45 ` James Morse [this message]
2020-02-16 18:53 ` [PATCH 5/5] KVM: arm64: Upgrade PMU support to ARMv8.4 Marc Zyngier
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