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From: Peter Xu <peterx@redhat.com>
To: Greg KH <greg@kroah.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Maxim Levitsky <mlevitsk@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v3 1/7] KVM: Allow to have arch-specific per-vm debugfs files
Date: Tue, 3 Aug 2021 15:25:58 -0400	[thread overview]
Message-ID: <YQmYRmidtS1XAydf@t490s> (raw)
In-Reply-To: <YQklR580FbVSiVz6@kroah.com>

On Tue, Aug 03, 2021 at 01:15:19PM +0200, Greg KH wrote:
> > +/*
> > + * Called after per-vm debugfs created.  When called kvm->debugfs_dentry should
> > + * be setup already, so we can create arch-specific debugfs entries under it.
> > + * Cleanup should be automatic done in kvm_destroy_vm_debugfs() recursively, so
> > + * a per-arch destroy interface is not needed.
> > + */
> > +int __weak kvm_arch_create_vm_debugfs(struct kvm *kvm)
> 
> This should be a void function, nothing should matter if creating
> debugfs files succeeds or not.
> 
> As proof, your one implementation always returned 0 :)

Right. :)

But we do have code that prepares for a failure on debugfs creations, please
have a look at kvm_create_vm_debugfs().  So I kept that for per-arch hook.

The existing x86 one should not fail, but it's a hope that we can convert some
other arch's existing debugfs code into per-arch hook like what we did with x86
here.  I didn't check again (please refer to the cover letter; we do have some
of those), but it's still easier to still allow per-arch hook to fail the vm
creation just like what we have for kvm_create_vm_debugfs().

PS: It makes sense to me to fail vm creation if 99% of those debugfs creation
failures are about -ENOMEM; e.g. early failure sounds better than failing right
after VM booted.

Meanwhile, I never expected to receive comments from you; thanks for having a
look!

-- 
Peter Xu


  reply	other threads:[~2021-08-03 19:26 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-30 22:04 [PATCH v3 0/7] KVM: X86: Some light optimizations on rmap logic Peter Xu
2021-07-30 22:04 ` [PATCH v3 1/7] KVM: Allow to have arch-specific per-vm debugfs files Peter Xu
2021-08-03 11:15   ` Greg KH
2021-08-03 19:25     ` Peter Xu [this message]
2021-07-30 22:04 ` [PATCH v3 2/7] KVM: X86: Introduce pte_list_count() helper Peter Xu
2021-07-30 22:04 ` [PATCH v3 3/7] KVM: X86: Introduce kvm_mmu_slot_lpages() helpers Peter Xu
2021-07-30 22:04 ` [PATCH v3 4/7] KVM: X86: Introduce mmu_rmaps_stat per-vm debugfs file Peter Xu
2021-08-02 15:25   ` Paolo Bonzini
2021-08-03 19:14     ` Peter Xu
2021-08-05 18:19     ` Sean Christopherson
2021-07-30 22:04 ` [PATCH v3 5/7] KVM: X86: MMU: Tune PTE_LIST_EXT to be bigger Peter Xu
2021-07-30 22:06 ` [PATCH v3 6/7] KVM: X86: Optimize pte_list_desc with per-array counter Peter Xu
2021-07-30 22:06 ` [PATCH v3 7/7] KVM: X86: Optimize zapping rmap Peter Xu

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