From: Fuad Tabba Date: Sun, 22 Feb 2026 08:33:52 +0000 (+0000) Subject: KVM: arm64: Revert accidental drop of kvm_uninit_stage2_mmu() for non-NV VMs X-Git-Tag: ceph-for-7.0-rc4~62^2^2~2 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=ec197dca8735f7627e5cff7e3fa8839b53a28514;p=ceph-client.git 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 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 Tested-by: Mark Brown Link: https://patch.msgid.link/20260222083352.89503-1-tabba@google.com Signed-off-by: Marc Zyngier --- 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];