KVM: arm64: Compute TPIDR_EL2 ignoring MTE tag

KASAN in HW_TAGS mode will store MTE tags in the top byte of the
pointer. When computing the offset for TPIDR_EL2 we don't want anything
in the top byte, so remove the tag to ensure the computation is correct
no matter what the tag.

Fixes: 94ab5b61ee16 ("kasan, arm64: enable CONFIG_KASAN_HW_TAGS")
Signed-off-by: Steven Price <steven.price@arm.com>
[maz: added comment]
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210108161254.53674-1-steven.price@arm.com

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 04c4485..fe60d25 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1396,8 +1396,9 @@ static void cpu_init_hyp_mode(void)
         * Calculate the raw per-cpu offset without a translation from the
         * kernel's mapping to the linear mapping, and store it in tpidr_el2
         * so that we can use adr_l to access per-cpu variables in EL2.
+        * Also drop the KASAN tag which gets in the way...
         */
-       params->tpidr_el2 = (unsigned long)this_cpu_ptr_nvhe_sym(__per_cpu_start) -
+       params->tpidr_el2 = (unsigned long)kasan_reset_tag(this_cpu_ptr_nvhe_sym(__per_cpu_start)) -
                            (unsigned long)kvm_ksym_ref(CHOOSE_NVHE_SYM(__per_cpu_start));
 
        params->mair_el2 = read_sysreg(mair_el1);