[PATCH 0/3] KVM: arm64: Fix teardown of non-protected VMs with pKVM

[Will Deacon <will@kernel.org>]

Hi folks,

Sashiko continues to throw rocks at me.

This time, it spotted that my fix (introduced in v5 [1] of the pKVM
series) to prevent taking a reference on a VM in the 'is_dying' state
also prevents unsharing of pages shared with a non-protected VM if that
VM is torn down by its VM fd being destroyed, rather than the usual path
via the MMU notifiers.

Rather than send a v6 of the whole series, here are three patches that
apply on top of v5 and fix the issue by (a) preventing teardown of a
referenced VM and (b) allowing some references to be taken on a dying
VM. As an added bonus, this simplifies the locking on the reclaim path
because now a VM reference is enough to stop the page-tables from going
away.

Cheers,

Will

[1] https://lore.kernel.org/kvmarm/20260330144841.26181-1-will@kernel.org

Cc: Marc Zyngier <maz@kernel.org>
Cc: Oliver Upton <oupton@kernel.org>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Zenghui Yu <yuzenghui@huawei.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Quentin Perret <qperret@google.com>
Cc: Fuad Tabba <tabba@google.com>
Cc: Vincent Donnefort <vdonnefort@google.com>
Cc: Mostafa Saleh <smostafa@google.com>
Cc: Alexandru Elisei <alexandru.elisei@arm.com>

--->8

Will Deacon (3):
  KVM: arm64: Prevent teardown finalisation of referenced 'hyp_vm'
  KVM: arm64: Allow get_pkvm_hyp_vm() to take a reference to a dying VM
  KVM: arm64: Don't hold 'vm_table_lock' across guest page reclaim

 arch/arm64/kvm/hyp/nvhe/pkvm.c | 53 +++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 27 deletions(-)

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2.53.0.1118.gaef5881109-goog