KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available()

[PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available()

Posted by Elliot Berman 3 years, 6 months ago

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;
+		else if (!is_kernel_in_hyp_mode())
 			kvm_mode = KVM_MODE_PROTECTED;
 		else
 			pr_warn_once("Protected KVM not available with VHE\n");

base-commit: 0982c8d859f8f7022b9fd44d421c7ec721bb41f9
-- 
2.25.1

Re: [PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available()

Posted by Catalin Marinas 3 years, 6 months ago

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.

-- 
Catalin

Re: [PATCH v2] KVM: arm64: Only set KVM_MODE_PROTECTED if is_hyp_mode_available()

Posted by Elliot Berman 3 years, 6 months ago


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?