[PATCH v9 03/20] KVM: arm64: Kill 32-bit vCPUs on systems with mismatched EL0 support

Will Deacon
2021-06-08T18:03:45Z

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>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/arm.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 1cb39c0803a4..5bdba97a7654 100644
--- 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
--
2.32.0.rc1.229.g3e70b5a671-goog