Commit 75cd027c authored by James Morse's avatar James Morse Committed by Oliver Upton
Browse files

KVM: arm64: selftests: Test ID_AA64PFR0.MPAM isn't completely ignored 



The ID_AA64PFR0.MPAM bit was previously accidentally exposed to guests,
and is ignored by KVM. KVM will always present the guest with 0 here,
and trap the MPAM system registers to inject an undef.

But, this value is still needed to prevent migration when the value
is incompatible with the target hardware. Add a kvm unit test to try
and write multiple values to ID_AA64PFR0.MPAM. Only the hardware value
previously exposed should be ignored, all other values should be
rejected.

Signed-off-by: default avatarJames Morse <james.morse@arm.com>
Signed-off-by: default avatarJoey Gouly <joey.gouly@arm.com>
Tested-by: default avatarShameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: default avatarGavin Shan <gshan@redhat.com>
Reviewed-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20241030160317.2528209-8-joey.gouly@arm.com


Signed-off-by: default avatarOliver Upton <oliver.upton@linux.dev>
parent 6685f5d5

tools/testing/selftests/kvm/aarch64/set_id_regs.c

+98 −1
Original line number Diff line number Diff line
@@ -443,6 +443,101 @@ static void test_vm_ftr_id_regs(struct kvm_vcpu *vcpu, bool aarch64_only) 
	}

}



#define MPAM_IDREG_TEST	6

static void test_user_set_mpam_reg(struct kvm_vcpu *vcpu)

{

	uint64_t masks[KVM_ARM_FEATURE_ID_RANGE_SIZE];

	struct reg_mask_range range = {

		.addr = (__u64)masks,

	};

	uint64_t val;

	int idx, err;



	/*

	 * If ID_AA64PFR0.MPAM is _not_ officially modifiable and is zero,

	 * check that if it can be set to 1, (i.e. it is supported by the

	 * hardware), that it can't be set to other values.

	 */



	/* Get writable masks for feature ID registers */

	memset(range.reserved, 0, sizeof(range.reserved));

	vm_ioctl(vcpu->vm, KVM_ARM_GET_REG_WRITABLE_MASKS, &range);



	/* Writeable? Nothing to test! */

	idx = encoding_to_range_idx(SYS_ID_AA64PFR0_EL1);

	if ((masks[idx] & ID_AA64PFR0_EL1_MPAM_MASK) == ID_AA64PFR0_EL1_MPAM_MASK) {

		ksft_test_result_skip("ID_AA64PFR0_EL1.MPAM is officially writable, nothing to test\n");

		return;

	}



	/* Get the id register value */

	vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), &val);



	/* Try to set MPAM=0. This should always be possible. */

	val &= ~ID_AA64PFR0_EL1_MPAM_MASK;

	val |= FIELD_PREP(ID_AA64PFR0_EL1_MPAM_MASK, 0);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), val);

	if (err)

		ksft_test_result_fail("ID_AA64PFR0_EL1.MPAM=0 was not accepted\n");

	else

		ksft_test_result_pass("ID_AA64PFR0_EL1.MPAM=0 worked\n");



	/* Try to set MPAM=1 */

	val &= ~ID_AA64PFR0_EL1_MPAM_MASK;

	val |= FIELD_PREP(ID_AA64PFR0_EL1_MPAM_MASK, 1);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), val);

	if (err)

		ksft_test_result_skip("ID_AA64PFR0_EL1.MPAM is not writable, nothing to test\n");

	else

		ksft_test_result_pass("ID_AA64PFR0_EL1.MPAM=1 was writable\n");



	/* Try to set MPAM=2 */

	val &= ~ID_AA64PFR0_EL1_MPAM_MASK;

	val |= FIELD_PREP(ID_AA64PFR0_EL1_MPAM_MASK, 2);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), val);

	if (err)

		ksft_test_result_pass("ID_AA64PFR0_EL1.MPAM not arbitrarily modifiable\n");

	else

		ksft_test_result_fail("ID_AA64PFR0_EL1.MPAM value should not be ignored\n");



	/* And again for ID_AA64PFR1_EL1.MPAM_frac */

	idx = encoding_to_range_idx(SYS_ID_AA64PFR1_EL1);

	if ((masks[idx] & ID_AA64PFR1_EL1_MPAM_frac_MASK) == ID_AA64PFR1_EL1_MPAM_frac_MASK) {

		ksft_test_result_skip("ID_AA64PFR1_EL1.MPAM_frac is officially writable, nothing to test\n");

		return;

	}



	/* Get the id register value */

	vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR1_EL1), &val);



	/* Try to set MPAM_frac=0. This should always be possible. */

	val &= ~ID_AA64PFR1_EL1_MPAM_frac_MASK;

	val |= FIELD_PREP(ID_AA64PFR1_EL1_MPAM_frac_MASK, 0);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR1_EL1), val);

	if (err)

		ksft_test_result_fail("ID_AA64PFR0_EL1.MPAM_frac=0 was not accepted\n");

	else

		ksft_test_result_pass("ID_AA64PFR0_EL1.MPAM_frac=0 worked\n");



	/* Try to set MPAM_frac=1 */

	val &= ~ID_AA64PFR1_EL1_MPAM_frac_MASK;

	val |= FIELD_PREP(ID_AA64PFR1_EL1_MPAM_frac_MASK, 1);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR1_EL1), val);

	if (err)

		ksft_test_result_skip("ID_AA64PFR1_EL1.MPAM_frac is not writable, nothing to test\n");

	else

		ksft_test_result_pass("ID_AA64PFR0_EL1.MPAM_frac=1 was writable\n");



	/* Try to set MPAM_frac=2 */

	val &= ~ID_AA64PFR1_EL1_MPAM_frac_MASK;

	val |= FIELD_PREP(ID_AA64PFR1_EL1_MPAM_frac_MASK, 2);

	err = __vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ID_AA64PFR1_EL1), val);

	if (err)

		ksft_test_result_pass("ID_AA64PFR1_EL1.MPAM_frac not arbitrarily modifiable\n");

	else

		ksft_test_result_fail("ID_AA64PFR1_EL1.MPAM_frac value should not be ignored\n");

}



static void test_guest_reg_read(struct kvm_vcpu *vcpu)

{

	bool done = false;
@@ -581,12 +676,14 @@ int main(void) 
		   ARRAY_SIZE(ftr_id_aa64isar2_el1) + ARRAY_SIZE(ftr_id_aa64pfr0_el1) +

		   ARRAY_SIZE(ftr_id_aa64pfr1_el1) + ARRAY_SIZE(ftr_id_aa64mmfr0_el1) +

		   ARRAY_SIZE(ftr_id_aa64mmfr1_el1) + ARRAY_SIZE(ftr_id_aa64mmfr2_el1) +

		   ARRAY_SIZE(ftr_id_aa64zfr0_el1) - ARRAY_SIZE(test_regs) + 2;

		   ARRAY_SIZE(ftr_id_aa64zfr0_el1) - ARRAY_SIZE(test_regs) + 2 +

		   MPAM_IDREG_TEST;



	ksft_set_plan(test_cnt);



	test_vm_ftr_id_regs(vcpu, aarch64_only);

	test_vcpu_ftr_id_regs(vcpu);

	test_user_set_mpam_reg(vcpu);



	test_guest_reg_read(vcpu);