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Fri, 11 Sep 2026 06:51:19 -0700 (PDT) Date: Fri, 11 Sep 2026 14:50:46 +0100 In-Reply-To: <20260911135053.146435-1-vdonnefort@google.com> Mime-Version: 1.0 References: <20260911135053.146435-1-vdonnefort@google.com> X-Mailer: git-send-email 2.55.0.1007.g17ff1f9808-goog Message-ID: <20260911135053.146435-16-vdonnefort@google.com> Subject: [PATCH v2 15/22] KVM: arm64: Warn on pKVM guest stage-2 block collapse From: Vincent Donnefort To: maz@kernel.org, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org Cc: joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, qperret@google.com, weilin.chang@arm.com, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260911_065122_082003_C40FF0F8 X-CRM114-Status: GOOD ( 10.33 ) 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 When pKVM is enabled, the host relies on a pkvm_mapping tree that mirrors the actual hypervisor-owned stage-2. The hypervisor is not allowed to silently split blocks or collapse page-tables. This should be treated as a bug. Therefore, WARN on guest stage-2 page-table collapse which would otherwise be fatal anyway. Signed-off-by: Vincent Donnefort --- arch/arm64/kvm/hyp/nvhe/mem_protect.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c index 2893183c2056..2e8c241f76c9 100644 --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c @@ -226,6 +226,12 @@ static void guest_s2_put_page(void *addr) hyp_put_page(¤t_vm->pool, addr); } +static void guest_s2_free_unlinked_table(void *addr, s8 level) +{ + /* We should never collapse guest stage-2 tables into blocks */ + WARN_ON(1); +} + static void __apply_guest_page(void *va, size_t size, void (*func)(void *addr, size_t size)) { @@ -294,6 +300,7 @@ int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd) .put_page = guest_s2_put_page, .dcache_clean_inval_poc = clean_dcache_guest_page, .icache_inval_pou = invalidate_icache_guest_page, + .free_unlinked_table = guest_s2_free_unlinked_table, }; guest_lock_component(vm); -- 2.55.0.1007.g17ff1f9808-goog