KVM: arm64: Kill 32-bit vCPUs on systems with mismatched EL0 support

If a vCPU is caught running 32-bit code on a system with mismatched
support at EL0, then we should kill it.

Acked-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210608180313.11502-4-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1cb39c0803a447872559c30f60437b67f21bbd71..5bdba97a76544e42a3033ec12a26e75aa7315c9e 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -692,6 +692,15 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
        }
 }
 
+static bool vcpu_mode_is_bad_32bit(struct kvm_vcpu *vcpu)
+{
+       if (likely(!vcpu_mode_is_32bit(vcpu)))
+               return false;
+
+       return !system_supports_32bit_el0() ||
+               static_branch_unlikely(&arm64_mismatched_32bit_el0);
+}
+
 /**
  * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
  * @vcpu:      The VCPU pointer
@@ -875,7 +884,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
                 * with the asymmetric AArch32 case), return to userspace with
                 * a fatal error.
                 */
-               if (!system_supports_32bit_el0() && vcpu_mode_is_32bit(vcpu)) {
+               if (vcpu_mode_is_bad_32bit(vcpu)) {
                        /*
                         * As we have caught the guest red-handed, decide that
                         * it isn't fit for purpose anymore by making the vcpu