+cc the actual kvmarm mailing list, what I had before was wishful
thinking that we moved off of the list that always goes to my spam :-)
On Fri, Apr 15, 2022 at 1:15 PM Oliver Upton <oupton@xxxxxxxxxx> wrote:
>
> The way KVM handles debugfs initialization and destruction is somewhat
> sloppy. Although the debugfs + stats bits get initialized *after*
> kvm_create_vm(), they are torn down from kvm_destroy_vm(). And yes,
> there is a window where we could theoretically destroy a VM before
> debugfs is ever instantiated.
>
> This series does away with the mess by coupling debugfs+stats to the
> overall VM create/destroy pattern. We already fail the VM creation if
> kvm_create_vm_debugfs() fails, so there really isn't a need to do these
> separately in the first place.
>
> The first two patches hoist some unrelated tidbits of stats state into
> the debugfs constructors just so its all handled under one roof.
>
> The second two patches realize the the intention of the series, changing
> the initialization order so we can get an FD for the vm early.
>
> Lastly, patch 5 is essentially a revert of Sean's proposed fix [1], but
> I deliberately am not proposing a revert outright, in case alarm bells
> go off that a stable patch got reverted (it is correct).
>
> Applies to the following commit w/ the addition of Sean's patch:
>
> fb649bda6f56 ("Merge tag 'block-5.18-2022-04-15' of git://git.kernel.dk/linux-block")
>
> Tested (I promise) on an Intel Skylake machine with KVM selftests. I
> poked around in debugfs to make sure there were no stragglers, and I ran
> the reproducer for [1] to confirm the null ptr deref wasn't introduced
> yet again.
>
> Oliver Upton (5):
> KVM: Shove vm stats_id init into kvm_create_vm_debugfs()
> KVM: Shove vcpu stats_id init into kvm_vcpu_create_debugfs()
> KVM: Get an fd before creating the VM
> KVM: Actually create debugfs in kvm_create_vm()
> KVM: Hoist debugfs_dentry init to kvm_create_vm_debugfs() (again)
>
> virt/kvm/kvm_main.c | 92 ++++++++++++++++++++++-----------------------
> 1 file changed, 46 insertions(+), 46 deletions(-)
>
> --
> 2.36.0.rc0.470.gd361397f0d-goog
>
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