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

Marc Zyngier maz at kernel.org
Mon Sep 29 09:04:57 PDT 2025


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 at 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




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