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| author | Fuad Tabba <tabba@google.com> | 2026-02-22 11:33:52 +0300 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2026-02-23 19:26:08 +0300 |
| commit | ec197dca8735f7627e5cff7e3fa8839b53a28514 (patch) | |
| tree | 93efdadbd8d978fb166cc082439613a05dd4d271 | |
| parent | 08f97454b7fa39bfcf82524955c771d2d693d6fe (diff) | |
| download | linux-ec197dca8735f7627e5cff7e3fa8839b53a28514.tar.xz | |
KVM: arm64: Revert accidental drop of kvm_uninit_stage2_mmu() for non-NV VMs
Commit 0c4762e26879 ("KVM: arm64: nv: Avoid NV stage-2 code when NV is
not supported") added an early return to several functions in
arch/arm64/kvm/nested.c to prevent a UBSAN shift-out-of-bounds error
when accessing the pgt union for non-nested VMs.
However, this early return was inadvertently applied to
kvm_arch_flush_shadow_all() as well, causing it to skip the call to
kvm_uninit_stage2_mmu(kvm) for all non-nested VMs.
For pKVM, skipping this teardown means the host never unshares the
guest's memory with the EL2 hypervisor. When the host kernel later
recycles these leaked pages for a new VM, it attempts to re-share them.
The hypervisor correctly rejects this with -EPERM, triggering a host
WARN_ON and hanging the guest.
Fix this by dropping the early return from kvm_arch_flush_shadow_all().
The for-loop guarding the nested MMU cleanup already bounds itself when
nested_mmus_size == 0, allowing execution to proceed to
kvm_uninit_stage2_mmu() as intended.
Reported-by: Mark Brown <broonie@kernel.org>
Closes: https://lore.kernel.org/all/60916cb6-f460-4751-b910-f63c58700ad0@sirena.org.uk/
Fixes: 0c4762e26879 ("KVM: arm64: nv: Avoid NV stage-2 code when NV is not supported")
Signed-off-by: Fuad Tabba <tabba@google.com>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://patch.msgid.link/20260222083352.89503-1-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
| -rw-r--r-- | arch/arm64/kvm/nested.c | 3 |
1 files changed, 0 insertions, 3 deletions
diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c index eeea5e692370..7f1ea85dc67a 100644 --- a/arch/arm64/kvm/nested.c +++ b/arch/arm64/kvm/nested.c @@ -1154,9 +1154,6 @@ void kvm_arch_flush_shadow_all(struct kvm *kvm) { int i; - if (!kvm->arch.nested_mmus_size) - return; - for (i = 0; i < kvm->arch.nested_mmus_size; i++) { struct kvm_s2_mmu *mmu = &kvm->arch.nested_mmus[i]; |