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Sun, 22 Feb 2026 00:33:53 -0800 (PST) Date: Sun, 22 Feb 2026 08:33:52 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.414.gf7e9f6c205-goog Message-ID: <20260222083352.89503-1-tabba@google.com> Subject: [PATCH v1] KVM: arm64: Revert accidental drop of kvm_uninit_stage2_mmu() for non-NV VMs From: Fuad Tabba To: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: broonie@kernel.org, maz@kernel.org, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, qperret@google.com, tabba@google.com Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260222_003356_166965_A5BA0303 X-CRM114-Status: GOOD ( 12.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 --- arch/arm64/kvm/nested.c | 3 --- 1 file changed, 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]; base-commit: 8bf22c33e7a172fbc72464f4cc484d23a6b412ba -- 2.53.0.414.gf7e9f6c205-goog