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From: Marc Zyngier <maz@kernel.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Elliot Berman <quic_eberman@quicinc.com>,
	Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
	Alexandru Elisei <alexandru.elisei@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
	David Brazdil <dbrazdil@google.com>
Subject: Re: [PATCH] KVM: arm64: Report Protected KVM cap only if KVM is enabled
Date: Fri, 09 Sep 2022 13:47:34 +0100	[thread overview]
Message-ID: <485617e0d3635c1961ab30c1ad930c81@kernel.org> (raw)
In-Reply-To: <Yxs1H3+iI8Y7+Zbu@arm.com>

On 2022-09-09 13:44, Catalin Marinas wrote:
> On Thu, Sep 01, 2022 at 09:01:22PM -0700, Elliot Berman wrote:
>> If "kvm-arm.mode=protected" is present on kernel command line, but the
>> kernel doesn't actually support KVM because it booted from EL1, the
>> ARM64_KVM_PROTECTED_MODE capability is misleadingly reported as 
>> present.
>> Fix this by adding a check whether we booted from EL2.
>> 
>> Cc: Will Deacon <will@kernel.org>
>> Cc: David Brazdil <dbrazdil@google.com>
>> Cc: Marc Zyngier <maz@kernel.org>
>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>> ---
>>  arch/arm64/kernel/cpufeature.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/arch/arm64/kernel/cpufeature.c 
>> b/arch/arm64/kernel/cpufeature.c
>> index 8d88433de81d..866667be0651 100644
>> --- a/arch/arm64/kernel/cpufeature.c
>> +++ b/arch/arm64/kernel/cpufeature.c
>> @@ -1974,7 +1974,7 @@ static void cpu_enable_mte(struct 
>> arm64_cpu_capabilities const *cap)
>>  #ifdef CONFIG_KVM
>>  static bool is_kvm_protected_mode(const struct arm64_cpu_capabilities 
>> *entry, int __unused)
>>  {
>> -	return kvm_get_mode() == KVM_MODE_PROTECTED;
>> +	return is_hyp_mode_available() && kvm_get_mode() == 
>> KVM_MODE_PROTECTED;
>>  }
>>  #endif /* CONFIG_KVM */
> 
> Could we not fix this in early_kvm_mode_cfg()?

That's be indeed preferable.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

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      reply	other threads:[~2022-09-09 12:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-02  4:01 [PATCH] KVM: arm64: Report Protected KVM cap only if KVM is enabled Elliot Berman
2022-09-09 12:44 ` Catalin Marinas
2022-09-09 12:47   ` Marc Zyngier [this message]

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