From: Marc Zyngier <maz@kernel.org>
To: Zenghui Yu <yuzenghui@huawei.com>,
kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Cc: Andrew Jones <drjones@redhat.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH 1/2] KVM: arm64: Don't write junk to sysregs on reset
Date: Tue, 6 Aug 2019 09:35:50 +0100 [thread overview]
Message-ID: <7b36f1dd-e44f-af75-0e51-8f6e705e81f6@kernel.org> (raw)
In-Reply-To: <01b74492-c59f-dfd9-e439-752e6b1c53dc@huawei.com>
On 06/08/2019 07:29, Zenghui Yu wrote:
> Hi Marc,
>
> On 2019/8/5 20:15, Marc Zyngier wrote:
>> At the moment, the way we reset system registers is mildly insane:
>> We write junk to them, call the reset functions, and then check that
>> we have something else in them.
>>
>> The "fun" thing is that this can happen while the guest is running
>> (PSCI, for example). If anything in KVM has to evaluate the state
>> of a system register while junk is in there, bad thing may happen.
>>
>> Let's stop doing that. Instead, we track that we have called a
>> reset function for that register, and assume that the reset
>> function has done something. This requires fixing a couple of
>> sysreg refinition in the trap table.
>>
>> In the end, the very need of this reset check is pretty dubious,
>> as it doesn't check everything (a lot of the sysregs leave outside of
>> the sys_regs[] array). It may well be axed in the near future.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>
> (Regardless of whether this check is needed or not,) I tested this patch
> with kvm-unit-tests:
>
> for i in {1..100}; do QEMU=/path/to/qemu-system-aarch64 accel=kvm
> arch=arm64 ./run_tests.sh; done
>
> And all the tests passed!
Great! Can I take this as a 'Tested-by:'?
Thanks,
M.
--
Jazz is not dead, it just smells funny...
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next prev parent reply other threads:[~2019-08-06 8:36 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-05 12:15 [PATCH 0/2] KVM: arm/arm64: Revamp sysreg reset checks Marc Zyngier
2019-08-05 12:15 ` [PATCH 1/2] KVM: arm64: Don't write junk to sysregs on reset Marc Zyngier
2019-08-06 6:29 ` Zenghui Yu
2019-08-06 8:35 ` Marc Zyngier [this message]
2019-08-06 8:52 ` Zenghui Yu
2019-08-05 12:15 ` [PATCH 2/2] KVM: arm: Don't write junk to CP15 registers " Marc Zyngier
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