[PATCH 13/13] KVM: arm64: selftest: Fix misleading comment about virtual timer encoding

Marc Zyngier
2025-09-29T16:05:08Z

The userspace-visible encoding for CNTV_CVAL_EL0 and CNTVCNT_EL0
have been swapped for as long as usersapce has had access to the
registers. This is documented in arch/arm64/include/uapi/asm/kvm.h.

Despite that, the get_reg_list test has unhelpful comments indicating
the wrong register for the encoding.

Replace this with definitions exposed in the include file, and
a comment explaining again the brokenness.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
.../testing/selftests/kvm/arm64/get-reg-list.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/arm64/get-reg-list.c b/tools/testing/selftests/kvm/arm64/get-reg-list.c
index 7a238755f0728..c9b84eeaab6b2 100644
--- a/tools/testing/selftests/kvm/arm64/get-reg-list.c
+++ b/tools/testing/selftests/kvm/arm64/get-reg-list.c
@@ -348,9 +348,20 @@ static __u64 base_regs[] = {
KVM_REG_ARM_FW_FEAT_BMAP_REG(1), /* KVM_REG_ARM_STD_HYP_BMAP */
KVM_REG_ARM_FW_FEAT_BMAP_REG(2), /* KVM_REG_ARM_VENDOR_HYP_BMAP */
KVM_REG_ARM_FW_FEAT_BMAP_REG(3), /* KVM_REG_ARM_VENDOR_HYP_BMAP_2 */
- ARM64_SYS_REG(3, 3, 14, 3, 1), /* CNTV_CTL_EL0 */
- ARM64_SYS_REG(3, 3, 14, 3, 2), /* CNTV_CVAL_EL0 */
- ARM64_SYS_REG(3, 3, 14, 0, 2),
+
+ /*
+ * EL0 Virtual Timer Registers
+ *
+ * WARNING:
+ * KVM_REG_ARM_TIMER_CVAL and KVM_REG_ARM_TIMER_CNT are not defined
+ * with the appropriate register encodings. Their values have been
+ * accidentally swapped. As this is set API, the definitions here
+ * must be used, rather than ones derived from the encodings.
+ */
+ KVM_ARM64_SYS_REG(SYS_CNTV_CTL_EL0),
+ KVM_REG_ARM_TIMER_CVAL,
+ KVM_REG_ARM_TIMER_CNT,
+
ARM64_SYS_REG(3, 0, 0, 0, 0), /* MIDR_EL1 */
ARM64_SYS_REG(3, 0, 0, 0, 6), /* REVIDR_EL1 */
ARM64_SYS_REG(3, 1, 0, 0, 1), /* CLIDR_EL1 */
--
2.47.3