[PATCH v7 1/3] KVM: selftests: arm64: Report set_id_reg reads of test registers as tests
Lorenzo Stoakes (ARM)
ljs at kernel.org
Mon Sep 28 08:26:57 PDT 2026
On Tue, Sep 01, 2026 at 07:50:01PM +0100, Mark Brown wrote:
> Currently when we run guest code to validate that the values we wrote to
> the registers are seen by the guest we assert that these values match using
> a KVM selftests level assert, resulting in unclear diagnostics if the test
> fails. Replace this assert with reporting a kselftest test per register.
>
> In order to support getting the names of the registers we repaint the array
> of ID_ registers to store the names and open code the rest.
>
> Reviewed-by: Ben Horgan <ben.horgan at arm.com>
> Signed-off-by: Mark Brown <broonie at kernel.org>
All looks reasonable to me.
Reviewed-by: Lorenzo Stoakes (ARM) <ljs at kernel.org>
Couple comments below but more like understanding-your-changes stuff.
> ---
> tools/testing/selftests/kvm/arm64/set_id_regs.c | 82 +++++++++++++++++++------
> 1 file changed, 63 insertions(+), 19 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/arm64/set_id_regs.c b/tools/testing/selftests/kvm/arm64/set_id_regs.c
> index 7429a1055df5..db6414a93ad3 100644
> --- a/tools/testing/selftests/kvm/arm64/set_id_regs.c
> +++ b/tools/testing/selftests/kvm/arm64/set_id_regs.c
> @@ -43,6 +43,7 @@ struct reg_ftr_bits {
> };
>
> struct test_feature_reg {
> + const char *name;
> u32 reg;
> const struct reg_ftr_bits *ftr_bits;
> };
> @@ -227,30 +228,32 @@ static const struct reg_ftr_bits ftr_id_aa64zfr0_el1[] = {
>
> #define TEST_REG(id, table) \
> { \
> - .reg = id, \
> + .name = #id, \
> + .reg = SYS_ ## id, \
> .ftr_bits = &((table)[0]), \
> }
>
> static struct test_feature_reg test_regs[] = {
> - TEST_REG(SYS_ID_AA64DFR0_EL1, ftr_id_aa64dfr0_el1),
> - TEST_REG(SYS_ID_DFR0_EL1, ftr_id_dfr0_el1),
> - TEST_REG(SYS_ID_AA64ISAR0_EL1, ftr_id_aa64isar0_el1),
> - TEST_REG(SYS_ID_AA64ISAR1_EL1, ftr_id_aa64isar1_el1),
> - TEST_REG(SYS_ID_AA64ISAR2_EL1, ftr_id_aa64isar2_el1),
> - TEST_REG(SYS_ID_AA64ISAR3_EL1, ftr_id_aa64isar3_el1),
> - TEST_REG(SYS_ID_AA64PFR0_EL1, ftr_id_aa64pfr0_el1),
> - TEST_REG(SYS_ID_AA64PFR1_EL1, ftr_id_aa64pfr1_el1),
> - TEST_REG(SYS_ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0_el1),
> - TEST_REG(SYS_ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1_el1),
> - TEST_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2_el1),
> - TEST_REG(SYS_ID_AA64MMFR3_EL1, ftr_id_aa64mmfr3_el1),
> - TEST_REG(SYS_ID_AA64ZFR0_EL1, ftr_id_aa64zfr0_el1),
> + TEST_REG(ID_AA64DFR0_EL1, ftr_id_aa64dfr0_el1),
> + TEST_REG(ID_DFR0_EL1, ftr_id_dfr0_el1),
> + TEST_REG(ID_AA64ISAR0_EL1, ftr_id_aa64isar0_el1),
> + TEST_REG(ID_AA64ISAR1_EL1, ftr_id_aa64isar1_el1),
> + TEST_REG(ID_AA64ISAR2_EL1, ftr_id_aa64isar2_el1),
> + TEST_REG(ID_AA64ISAR3_EL1, ftr_id_aa64isar3_el1),
> + TEST_REG(ID_AA64PFR0_EL1, ftr_id_aa64pfr0_el1),
> + TEST_REG(ID_AA64PFR1_EL1, ftr_id_aa64pfr1_el1),
> + TEST_REG(ID_AA64MMFR0_EL1, ftr_id_aa64mmfr0_el1),
> + TEST_REG(ID_AA64MMFR1_EL1, ftr_id_aa64mmfr1_el1),
> + TEST_REG(ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2_el1),
> + TEST_REG(ID_AA64MMFR3_EL1, ftr_id_aa64mmfr3_el1),
> + TEST_REG(ID_AA64ZFR0_EL1, ftr_id_aa64zfr0_el1),
> };
>
> #define GUEST_REG_SYNC(id) GUEST_SYNC_ARGS(0, id, read_sysreg_s(id), 0, 0);
>
> static void guest_code(void)
> {
> + /* Registers in test_regs array */
> GUEST_REG_SYNC(SYS_ID_AA64DFR0_EL1);
> GUEST_REG_SYNC(SYS_ID_DFR0_EL1);
> GUEST_REG_SYNC(SYS_ID_AA64ISAR0_EL1);
> @@ -264,6 +267,8 @@ static void guest_code(void)
> GUEST_REG_SYNC(SYS_ID_AA64MMFR2_EL1);
> GUEST_REG_SYNC(SYS_ID_AA64MMFR3_EL1);
> GUEST_REG_SYNC(SYS_ID_AA64ZFR0_EL1);
> +
> + /* Additional registers counted in NUM_EXTRA_REGS */
> GUEST_REG_SYNC(SYS_MPIDR_EL1);
> GUEST_REG_SYNC(SYS_CLIDR_EL1);
> GUEST_REG_SYNC(SYS_CTR_EL0);
> @@ -274,6 +279,35 @@ static void guest_code(void)
> GUEST_DONE();
> }
>
> +#define NUM_EXTRA_REGS 6
> +#define GUEST_READ_TEST (ARRAY_SIZE(test_regs) + NUM_EXTRA_REGS)
> +
> +static const char *get_reg_name(u64 id)
> +{
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(test_regs); i++)
> + if (test_regs[i].reg == id)
> + return test_regs[i].name;
> +
> + switch (id) {
> + case SYS_MPIDR_EL1:
> + return "MPIDR_EL1";
> + case SYS_CLIDR_EL1:
> + return "CLIDR_EL1";
> + case SYS_CTR_EL0:
> + return "CTR_EL0";
> + case SYS_MIDR_EL1:
> + return "MIDR_EL1";
> + case SYS_REVIDR_EL1:
> + return "REVIDR_EL1";
> + case SYS_AIDR_EL1:
> + return "AIDR_EL1";
> + default:
> + TEST_FAIL("Unknown register");
> + }
I guess these are for GUEST_REG_SYNC() registers, etc. that don't appear in the
TEST_REG() list?
> +}
> +
> /* Return a safe value to a given ftr_bits an ftr value */
> u64 get_safe_value(const struct reg_ftr_bits *ftr_bits, u64 ftr)
> {
> @@ -674,7 +708,8 @@ static void test_guest_reg_read(struct kvm_vcpu *vcpu)
> struct ucall uc;
>
> while (!done) {
> - u64 val;
> + u64 reg_id, expected_val, guest_val;
> + bool match;
>
> vcpu_run(vcpu);
>
> @@ -683,11 +718,20 @@ static void test_guest_reg_read(struct kvm_vcpu *vcpu)
> REPORT_GUEST_ASSERT(uc);
> break;
> case UCALL_SYNC:
> - val = test_reg_vals[encoding_to_range_idx(uc.args[2])];
> - val = reset_mutable_bits(uc.args[2], val);
> + expected_val = test_reg_vals[encoding_to_range_idx(uc.args[2])];
> + expected_val = reset_mutable_bits(uc.args[2], expected_val);
>
> /* Make sure the written values are seen by guest */
> - TEST_ASSERT_EQ(val, reset_mutable_bits(uc.args[2], uc.args[3]));
> + reg_id = uc.args[2];
> + guest_val = reset_mutable_bits(uc.args[2], uc.args[3]);
> +
> + match = expected_val == guest_val;
> + if (!match)
> + ksft_print_msg("%lx != %lx\n",
> + expected_val, guest_val);
> + ksft_test_result(match,
> + "%s value seen in guest\n",
> + get_reg_name(reg_id));
> break;
> case UCALL_DONE:
> done = true;
> @@ -828,7 +872,7 @@ int main(void)
>
> ksft_print_header();
>
> - test_cnt = 3 + MPAM_IDREG_TEST + MTE_IDREG_TEST;
> + test_cnt = 3 + MPAM_IDREG_TEST + MTE_IDREG_TEST + GUEST_READ_TEST;
I guess because you made things use TAP now?
> for (i = 0; i < ARRAY_SIZE(test_regs); i++)
> for (j = 0; test_regs[i].ftr_bits[j].type != FTR_END; j++)
> test_cnt++;
>
> --
> 2.47.3
>
>
--
Cheers, Lorenzo
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