From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org,
Peng Liang <liangpeng10@huawei.com>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH 1/3] KVM: arm64: Allow setting of ID_AA64PFR0_EL1.CSV2 from userspace
Date: Fri, 06 Nov 2020 09:57:04 +0000 [thread overview]
Message-ID: <32241e9ee49133df4e9bcc6c8ebd7551@kernel.org> (raw)
In-Reply-To: <20201105224442.GD8842@willie-the-truck>
On 2020-11-05 22:44, Will Deacon wrote:
>> + if (csv2 > vcpu->kvm->arch.pfr0_csv2)
>> + return -EINVAL;
>> + vcpu->kvm->arch.pfr0_csv2 = csv2;
>> +
>> + /* This is what we mean by invariant: you can't change it. */
>> + if (val != read_id_reg(vcpu, rd, false))
>> + return -EINVAL;
>
> I think it's quite confusing to return -EINVAL in the case that we have
> actually updated arch.pfr0_csv2, as it's indistinguishable from the
> case
> when csv2 was invalid and the field wasn't updated.
-EINVAL is the right error code here (you're setting an invalid value
for
the whole register). The bug is that we have now changed CSV2 for
everyone.
I'll have a look at fixing this, though it might involve some locking.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2020-11-06 9:57 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-03 17:14 [PATCH 0/3] KVM: arm64: Another set of CSV2-related fixes Marc Zyngier
2020-11-03 17:14 ` [PATCH 1/3] KVM: arm64: Allow setting of ID_AA64PFR0_EL1.CSV2 from userspace Marc Zyngier
2020-11-05 22:44 ` Will Deacon
2020-11-06 9:57 ` Marc Zyngier [this message]
2020-11-03 17:14 ` [PATCH 2/3] KVM: arm64: Rename access_amu() to undef_access() Marc Zyngier
2020-11-05 22:50 ` Will Deacon
2020-11-06 10:54 ` Marc Zyngier
2020-11-03 17:14 ` [PATCH 3/3] KVM: arm64: Handle SCXTNUM_ELx traps Marc Zyngier
2020-11-05 22:50 ` Will Deacon
2020-11-12 22:21 [PATCH 0/3] KVM/arm64 fixes for 5.10, take #3 Marc Zyngier
2020-11-12 22:21 ` [PATCH 1/3] KVM: arm64: Allow setting of ID_AA64PFR0_EL1.CSV2 from userspace Marc Zyngier
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