[PATCH v2 2/2] KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3 compatibility

[Marc Zyngier]

On 2021-01-15 14:08, Ard Biesheuvel wrote:
> On Fri, 15 Jan 2021 at 15:03, Marc Zyngier <maz at kernel.org> wrote:

[...]

>> diff --git a/arch/arm64/kvm/vgic/vgic-v3.c 
>> b/arch/arm64/kvm/vgic/vgic-v3.c
>> index 8e7bf3151057..67b27b47312b 100644
>> --- a/arch/arm64/kvm/vgic/vgic-v3.c
>> +++ b/arch/arm64/kvm/vgic/vgic-v3.c
>> @@ -584,8 +584,10 @@ early_param("kvm-arm.vgic_v4_enable", 
>> early_gicv4_enable);
>>  int vgic_v3_probe(const struct gic_kvm_info *info)
>>  {
>>         u64 ich_vtr_el2 = kvm_call_hyp_ret(__vgic_v3_get_gic_config);
>> +       bool has_v2;
>>         int ret;
>> 
>> +       has_v2 = ich_vtr_el2 >> 63;
>>         ich_vtr_el2 = (u32)ich_vtr_el2;
>> 
>>         /*
>> @@ -605,13 +607,15 @@ int vgic_v3_probe(const struct gic_kvm_info 
>> *info)
>>                          gicv4_enable ? "en" : "dis");
>>         }
>> 
>> +       kvm_vgic_global_state.vcpu_base = 0;
>> +
>>         if (!info->vcpu.start) {
>>                 kvm_info("GICv3: no GICV resource entry\n");
>> -               kvm_vgic_global_state.vcpu_base = 0;
>> +       } else if (!has_v2) {
>> +               pr_warn("CPU interface incapable of MMIO access\n");
> 
> Could we include FW_BUG here to stress that this is a firmware problem?

Absolutely! That's what it now looks like:

[    2.648452] kvm [1]: IPA Size Limit: 40 bits
[    2.649259] [Firmware Bug]: CPU interface incapable of MMIO access
[    2.649620] kvm [1]: disabling GICv2 emulation
[    2.650227] kvm [1]: GIC system register CPU interface enabled
[    2.652004] kvm [1]: vgic interrupt IRQ9
[    2.655623] kvm [1]: VHE mode initialized successfully

Updated version pushed out.

Thanks,

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