Commit 2e04378f authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Handle trapping of FEAT_LS64* instructions 



We generally don't expect FEAT_LS64* instructions to trap, unless
they are trapped by a guest hypervisor.

Otherwise, this is just the guest playing tricks on us by using
an instruction that isn't advertised, which we handle with a well
deserved UNDEF.

Reviewed-by: default avatarJoey Gouly <joey.gouly@arm.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 4b4af68d

arch/arm64/kvm/handle_exit.c

+56 −0
Original line number Diff line number Diff line
@@ -298,6 +298,61 @@ static int handle_svc(struct kvm_vcpu *vcpu) 
	return 1;

}



static int handle_other(struct kvm_vcpu *vcpu)

{

	bool is_l2 = vcpu_has_nv(vcpu) && !is_hyp_ctxt(vcpu);

	u64 hcrx = __vcpu_sys_reg(vcpu, HCRX_EL2);

	u64 esr = kvm_vcpu_get_esr(vcpu);

	u64 iss = ESR_ELx_ISS(esr);

	struct kvm *kvm = vcpu->kvm;

	bool allowed, fwd = false;



	/*

	 * We only trap for two reasons:

	 *

	 * - the feature is disabled, and the only outcome is to

	 *   generate an UNDEF.

	 *

	 * - the feature is enabled, but a NV guest wants to trap the

	 *   feature used by its L2 guest. We forward the exception in

	 *   this case.

	 *

	 * What we don't expect is to end-up here if the guest is

	 * expected be be able to directly use the feature, hence the

	 * WARN_ON below.

	 */

	switch (iss) {

	case ESR_ELx_ISS_OTHER_ST64BV:

		allowed = kvm_has_feat(kvm, ID_AA64ISAR1_EL1, LS64, LS64_V);

		if (is_l2)

			fwd = !(hcrx & HCRX_EL2_EnASR);

		break;

	case ESR_ELx_ISS_OTHER_ST64BV0:

		allowed = kvm_has_feat(kvm, ID_AA64ISAR1_EL1, LS64, LS64_ACCDATA);

		if (is_l2)

			fwd = !(hcrx & HCRX_EL2_EnAS0);

		break;

	case ESR_ELx_ISS_OTHER_LDST64B:

		allowed = kvm_has_feat(kvm, ID_AA64ISAR1_EL1, LS64, LS64);

		if (is_l2)

			fwd = !(hcrx & HCRX_EL2_EnALS);

		break;

	default:

		/* Clearly, we're missing something. */

		WARN_ON_ONCE(1);

		allowed = false;

	}



	WARN_ON_ONCE(allowed && !fwd);



	if (allowed && fwd)

		kvm_inject_nested_sync(vcpu, esr);

	else

		kvm_inject_undefined(vcpu);



	return 1;

}



static exit_handle_fn arm_exit_handlers[] = {

	[0 ... ESR_ELx_EC_MAX]	= kvm_handle_unknown_ec,

	[ESR_ELx_EC_WFx]	= kvm_handle_wfx,
@@ -307,6 +362,7 @@ static exit_handle_fn arm_exit_handlers[] = { 
	[ESR_ELx_EC_CP14_LS]	= kvm_handle_cp14_load_store,

	[ESR_ELx_EC_CP10_ID]	= kvm_handle_cp10_id,

	[ESR_ELx_EC_CP14_64]	= kvm_handle_cp14_64,

	[ESR_ELx_EC_OTHER]	= handle_other,

	[ESR_ELx_EC_HVC32]	= handle_hvc,

	[ESR_ELx_EC_SMC32]	= handle_smc,

	[ESR_ELx_EC_HVC64]	= handle_hvc,