From 75cd027cbcb161e277209e20df14f0818c62d9e7 Mon Sep 17 00:00:00 2001 From: James Morse Date: Wed, 30 Oct 2024 16:03:17 +0000 Subject: 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: James Morse Signed-off-by: Joey Gouly Tested-by: Shameer Kolothum Reviewed-by: Gavin Shan Reviewed-by: Marc Zyngier Link: https://lore.kernel.org/r/20241030160317.2528209-8-joey.gouly@arm.com Signed-off-by: Oliver Upton --- tools/testing/selftests/kvm/aarch64/set_id_regs.c | 99 ++++++++++++++++++++++- 1 file changed, 98 insertions(+), 1 deletion(-) diff --git a/tools/testing/selftests/kvm/aarch64/set_id_regs.c b/tools/testing/selftests/kvm/aarch64/set_id_regs.c index b87e53580bfc..a79b7f18452d 100644 --- a/tools/testing/selftests/kvm/aarch64/set_id_regs.c +++ b/tools/testing/selftests/kvm/aarch64/set_id_regs.c @@ -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); -- cgit v1.2.3