[PATCH kernel] KVM: PPC: Book3S HV: Make unique debugfs nodename

[Alexey Kardashevskiy]

On 24/08/2021 18:37, Alexey Kardashevskiy wrote:
> 
> 
> On 18/08/2021 08:20, Fabiano Rosas wrote:
>> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>>
>>> On 07/07/2021 14:13, Alexey Kardashevskiy wrote:
>>
>>> alternatively move this debugfs stuff under the platform-independent
>>> directory, how about that?
>>
>> That's a good idea. I only now realized we have two separate directories
>> for the same guest:
>>
>> $ ls /sys/kernel/debug/kvm/ | grep $pid
>> 19062-11
>> vm19062
>>
>> Looks like we would have to implement kvm_arch_create_vcpu_debugfs for
>> the vcpu information and add a similar hook for the vm.
> 
> Something like that. From the git history, it looks like the ppc folder 
> was added first and then the generic kvm folder was added but apparently 
> they did not notice the ppc one due to natural reasons :)
> 
> If you are not too busy, can you please merge the ppc one into the 
> generic one and post the patch, so we won't need to fix these 
> duplication warnings again? Thanks,



Turns out it is not that straight forward as I thought as the common KVM 
debugfs entry is created after PPC HV KVM created its own and there is 
no obvious way to change the order (no "post init" hook in kvmppc_ops).

Also, unlike the common KVM debugfs setup, we do not allocate structures 
to support debugfs nodes so we do not leak anything to bother with a 
mutex like 85cd39af14f4 did.

So I'd stick to the original patch to reduce the noise in the dmesg, and 
it also exposes lpid which I find rather useful for finding the right 
partition scope tree in partition_tb.

Michael?


> 
> 
> 
>>>> ---
>>>>    arch/powerpc/kvm/book3s_hv.c | 2 +-
>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/arch/powerpc/kvm/book3s_hv.c 
>>>> b/arch/powerpc/kvm/book3s_hv.c
>>>> index 1d1fcc290fca..0223ddc0eed0 100644
>>>> --- a/arch/powerpc/kvm/book3s_hv.c
>>>> +++ b/arch/powerpc/kvm/book3s_hv.c
>>>> @@ -5227,7 +5227,7 @@ static int kvmppc_core_init_vm_hv(struct kvm 
>>>> *kvm)
>>>>        /*
>>>>         * Create a debugfs directory for the VM
>>>>         */
>>>> -    snprintf(buf, sizeof(buf), "vm%d", current->pid);
>>>> +    snprintf(buf, sizeof(buf), "vm%d-lp%ld", current->pid, lpid);
>>>>        kvm->arch.debugfs_dir = debugfs_create_dir(buf, 
>>>> kvm_debugfs_dir);
>>>>        kvmppc_mmu_debugfs_init(kvm);
>>>>        if (radix_enabled())
>>>>
> 

-- 
Alexey