From: Marc Zyngier <maz@kernel.org>
To: Mark Rutland <mark.rutland@arm.com>
Cc: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>,
rnayak@codeaurora.org, suzuki.poulose@arm.com,
catalin.marinas@arm.com, linux-kernel@vger.kernel.org,
jeremy.linton@arm.com, bjorn.andersson@linaro.org,
linux-arm-msm@vger.kernel.org, andrew.murray@arm.com,
will@kernel.org, Dave.Martin@arm.com,
linux-arm-kernel@lists.infradead.org
Subject: Re: Relax CPU features sanity checking on heterogeneous architectures
Date: Fri, 11 Oct 2019 14:33:43 +0100 [thread overview]
Message-ID: <20191011143343.541da66c@why> (raw)
In-Reply-To: <20191011105010.GA29364@lakrids.cambridge.arm.com>
On Fri, 11 Oct 2019 11:50:11 +0100
Mark Rutland <mark.rutland@arm.com> wrote:
> Hi,
>
> On Fri, Oct 11, 2019 at 11:19:00AM +0530, Sai Prakash Ranjan wrote:
> > On latest QCOM SoCs like SM8150 and SC7180 with big.LITTLE arch, below
> > warnings are observed during bootup of big cpu cores.
>
> For reference, which CPUs are in those SoCs?
>
> > SM8150:
> >
> > [ 0.271177] CPU features: SANITY CHECK: Unexpected variation in
> > SYS_ID_AA64PFR0_EL1. Boot CPU: 0x00000011112222, CPU4: 0x00000011111112
>
> The differing fields are EL3, EL2, and EL1: the boot CPU supports
> AArch64 and AArch32 at those exception levels, while the secondary only
> supports AArch64.
>
> Do we handle this variation in KVM?
We do, at least at vcpu creation time (see kvm_reset_vcpu). But if one
of the !AArch32 CPU comes in late in the game (after we've started a
guest), all bets are off (we'll schedule the 32bit guest on that CPU,
enter the guest, immediately take an Illegal Exception Return, and
return to userspace with KVM_EXIT_FAIL_ENTRY).
Not sure we could do better, given the HW. My preference would be to
fail these CPUs if they aren't present at boot time.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2019-10-11 13:33 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 5:49 Relax CPU features sanity checking on heterogeneous architectures Sai Prakash Ranjan
2019-10-11 9:19 ` Marc Gonzalez
2019-10-11 9:57 ` Sai Prakash Ranjan
2019-10-11 10:50 ` Mark Rutland
2019-10-11 11:09 ` Marc Gonzalez
2019-10-11 13:33 ` Sai Prakash Ranjan
2019-10-11 13:17 ` Sai Prakash Ranjan
2019-10-11 13:34 ` Marc Zyngier
2019-10-11 13:40 ` Sai Prakash Ranjan
2019-10-17 20:00 ` Stephen Boyd
2019-10-18 7:20 ` Marc Zyngier
2019-10-18 14:33 ` Stephen Boyd
2019-10-18 16:40 ` Marc Zyngier
2019-10-18 10:18 ` Sai Prakash Ranjan
2019-10-11 13:33 ` Marc Zyngier [this message]
2019-10-11 13:54 ` Mark Rutland
2019-10-11 14:06 ` Marc Zyngier
2019-10-17 21:39 ` Jeremy Linton
2019-10-18 9:01 ` Catalin Marinas
2020-01-20 2:47 ` Sai Prakash Ranjan
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