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Message-ID: <05057e2a-1a85-69ba-ffcd-584d4090467a@quicinc.com>
Date:   Fri, 9 Sep 2022 10:55:18 -0700
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Subject: Re: [PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if
 is_hyp_mode_available()
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To:     Catalin Marinas <catalin.marinas@arm.com>
CC:     Will Deacon <will@kernel.org>, Marc Zyngier <maz@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>
References: <20220909144552.3000716-1-quic_eberman@quicinc.com>
 <Yxt3wmXYYbWraXrd@arm.com>
From:   Elliot Berman <quic_eberman@quicinc.com>
In-Reply-To: <Yxt3wmXYYbWraXrd@arm.com>
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On 9/9/2022 10:28 AM, Catalin Marinas wrote:
> On Fri, Sep 09, 2022 at 07:45:52AM -0700, Elliot Berman wrote:
>> Do not switch kvm_mode to KVM_MODE_PROTECTED if hypervisor mode is not
>> available. This prevents "Protected KVM" cpu capability being reported
>> when Linux is booting in EL1 and would not have KVM enabled.
>>
>> Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>
>> ---
>>   arch/arm64/kvm/arm.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
>> index 8fe73ee5fa84..861f4b388879 100644
>> --- a/arch/arm64/kvm/arm.c
>> +++ b/arch/arm64/kvm/arm.c
>> @@ -2272,7 +2272,9 @@ static int __init early_kvm_mode_cfg(char *arg)
>>   		return -EINVAL;
>>   
>>   	if (strcmp(arg, "protected") == 0) {
>> -		if (!is_kernel_in_hyp_mode())
>> +		if (!is_hyp_mode_available())
>> +			kvm_mode = KVM_MODE_DEFAULT;
> 
> I think kvm_mode is already KVM_MODE_DEFAULT at this point. You may want
> to print a warning instead.
> 

Does it make sense to print warning for kvm-arm.mode=nvhe as well?