Commit 75b2fdc1 authored by Oliver Upton's avatar Oliver Upton Committed by Marc Zyngier
Browse files

KVM: arm64: selftests: Cope with arch silliness in EL2 selftest 



Implementations without FEAT_FGT aren't required to trap the entire ID
register space when HCR_EL2.TID3 is set. This is a terrible idea, as the
hypervisor may need to advertise the absence of a feature to the VM
using a negative value in a signed field, FEAT_E2H0 being a great
example of this.

Cope with uncooperative implementations in the EL2 selftest by accepting
a zero value when FEAT_FGT is absent and otherwise only tolerating the
expected nonzero value.

Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent f677b0ef

tools/testing/selftests/kvm/arm64/hello_el2.c

+15 −2
Original line number Diff line number Diff line
@@ -13,15 +13,28 @@ 


static void guest_code(void)

{

	u64 mmfr0 = read_sysreg_s(SYS_ID_AA64MMFR0_EL1);

	u64 mmfr1 = read_sysreg_s(SYS_ID_AA64MMFR1_EL1);

	u64 mmfr4 = read_sysreg_s(SYS_ID_AA64MMFR4_EL1);

	u8 e2h0 = SYS_FIELD_GET(ID_AA64MMFR4_EL1, E2H0, mmfr4);



	GUEST_ASSERT_EQ(get_current_el(), 2);

	GUEST_ASSERT(read_sysreg(hcr_el2) & HCR_EL2_E2H);

	GUEST_ASSERT_EQ(SYS_FIELD_GET(ID_AA64MMFR1_EL1, VH, mmfr1),

			ID_AA64MMFR1_EL1_VH_IMP);

	GUEST_ASSERT_EQ(SYS_FIELD_GET(ID_AA64MMFR4_EL1, E2H0, mmfr4),

			ID_AA64MMFR4_EL1_E2H0_NI_NV1);



	/*

	 * Traps of the complete ID register space are IMPDEF without FEAT_FGT,

	 * which is really annoying to deal with in KVM describing E2H as RES1.

	 *

	 * If the implementation doesn't honor the trap then expect the register

	 * to return all zeros.

	 */

	if (e2h0 == ID_AA64MMFR4_EL1_E2H0_IMP)

		GUEST_ASSERT_EQ(SYS_FIELD_GET(ID_AA64MMFR0_EL1, FGT, mmfr0),

				ID_AA64MMFR0_EL1_FGT_NI);

	else

		GUEST_ASSERT_EQ(e2h0, ID_AA64MMFR4_EL1_E2H0_NI_NV1);



	GUEST_DONE();

}