On 03/07/2023 17:35, Marc Zyngier wrote:
> Since 0bf50497f03b ("KVM: Drop kvm_count_lock and instead protect
> kvm_usage_count with kvm_lock"), hotplugging back a CPU whilst
> a guest is running results in a number of ugly splats as most
> of this code expects to run with preemption disabled, which isn't
> the case anymore.
>
> While the context is preemptable, it isn't migratable, which should
> be enough. But we have plenty of preemptible() checks all over
> the place, and our per-CPU accessors also disable preemption.
>
> Since this affects released versions, let's do the easy fix first,
> disabling preemption in kvm_arch_hardware_enable(). We can always
> revisit this with a more invasive fix in the future.
>
> Fixes: 0bf50497f03b ("KVM: Drop kvm_count_lock and instead protect kvm_usage_count with kvm_lock")
> Reported-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
> Tested-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/aeab7562-2d39-e78e-93b1-4711f8cc3fa5@xxxxxxx
> Cc: stable@xxxxxxxxxxxxxxx # v6.3, v6.4
Typo here, didn't make it to the stable list (kernek.org -> kernel.org)
Kristina
