Re: [PATCH kernel v3] KVM: PPC: Merge powerpc's debugfs entry content into generic entry

On 12/16/21 05:11, Cédric Le Goater wrote:
> On 12/15/21 02:33, Alexey Kardashevskiy wrote:
>> At the moment KVM on PPC creates 3 types of entries under the kvm debugfs:
>> 1) "%pid-%fd" per a KVM instance (for all platforms);
>> 2) "vm%pid" (for PPC Book3s HV KVM);
>> 3) "vm%u_vcpu%u_timing" (for PPC Book3e KVM).
>>
>> The problem with this is that multiple VMs per process is not allowed for
>> 2) and 3) which makes it possible for userspace to trigger errors when
>> creating duplicated debugfs entries.
>>
>> This merges all these into 1).
>>
>> This defines kvm_arch_create_kvm_debugfs() similar to
>> kvm_arch_create_vcpu_debugfs().
>>
>> This defines 2 hooks in kvmppc_ops that allow specific KVM implementations
>> add necessary entries, this adds the _e500 suffix to
>> kvmppc_create_vcpu_debugfs_e500() to make it clear what platform it is for.
>>
>> This makes use of already existing kvm_arch_create_vcpu_debugfs() on PPC.
>>
>> This removes no more used debugfs_dir pointers from PPC kvm_arch structs.
>>
>> This stops removing vcpu entries as once created vcpus stay around
>> for the entire life of a VM and removed when the KVM instance is closed,
>> see commit d56f5136b010 ("KVM: let kvm_destroy_vm_debugfs clean up vCPU
>> debugfs directories").
> 
> It would nice to also move the KVM device debugfs files :
> 
>    /sys/kernel/debug/powerpc/kvm-xive-%p
> 
> These are dynamically created and destroyed at run time depending
> on the interrupt mode negociated by CAS. It might be more complex ?

With this addition:

diff --git a/arch/powerpc/kvm/book3s_xive_native.c
b/arch/powerpc/kvm/book3s_xive_native.c
index 99db9ac49901..511f643e2875 100644
--- a/arch/powerpc/kvm/book3s_xive_native.c
+++ b/arch/powerpc/kvm/book3s_xive_native.c
@@ -1267,10 +1267,10 @@ static void xive_native_debugfs_init(struct
kvmppc_xive *xive)
                return;
        }

-       xive->dentry = debugfs_create_file(name, 0444, arch_debugfs_dir,
+       xive->dentry = debugfs_create_file(name, 0444,
xive->kvm->debugfs_dentry,
                                           xive, &xive_native_debug_fops);


it looks fine, this is "before":

root@zz1:/sys/kernel/debug# find -iname "*xive*"
./slab/xive-provision
./powerpc/kvm-xive-c0000000208c0000
./powerpc/xive


and this is "after" the patch applied.

root@zz1:/sys/kernel/debug# find -iname "*xive*"
./kvm/29058-11/kvm-xive-c0000000208c0000
./slab/xive-provision
./powerpc/xive


I'll repost unless there is something more to it. Thanks,


-- 
Alexey