linux-kernel - [PATCH] KVM: selftests: Track width of arm64's timer counter as "int", not "uint64

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Message-ID: <20250926155838.2612205-1-seanjc@google.com>
Date: Fri, 26 Sep 2025 08:58:38 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>
Cc: linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-kernel@...r.kernel.org, Sebastian Ott <sebott@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>
Subject: [PATCH] KVM: selftests: Track width of arm64's timer counter as
 "int", not "uint64_t"

Store the width of arm64's timer counter as an "int", not a "uint64_t".
ilog2() returns an "int", and more importantly using what is an "unsigned
long" under the hood makes clang unhappy due to a type mismatch when
clamping the width to a sane value.

  arm64/arch_timer_edge_cases.c:1032:10: error: comparison of distinct pointer types
     ('typeof (width) *' (aka 'unsigned long *') and 'typeof (56) *' (aka 'int *'))
     [-Werror,-Wcompare-distinct-pointer-types]
   1032 |         width = clamp(width, 56, 64);
        |                 ^~~~~~~~~~~~~~~~~~~~
  tools/include/linux/kernel.h:47:45: note: expanded from macro 'clamp'
     47 | #define clamp(val, lo, hi)      min((typeof(val))max(val, lo), hi)
        |                                                  ^~~~~~~~~~~~
  tools/include/linux/kernel.h:33:17: note: expanded from macro 'max'
     33 |         (void) (&_max1 == &_max2);              \
        |                 ~~~~~~ ^  ~~~~~~
  tools/include/linux/kernel.h:39:9: note: expanded from macro 'min'
     39 |         typeof(x) _min1 = (x);                  \
        |                ^

Fixes: fad4cf944839 ("KVM: arm64: selftests: Determine effective counter width in arch_timer_edge_cases")
Cc: Sebastian Ott <sebott@...hat.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c b/tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c
index ce74d069cb7b..38493c9cde83 100644
--- a/tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c
+++ b/tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c
@@ -1027,7 +1027,7 @@ static void set_counter_defaults(void)
 {
 	const uint64_t MIN_ROLLOVER_SECS = 40ULL * 365 * 24 * 3600;
 	uint64_t freq = read_sysreg(CNTFRQ_EL0);
-	uint64_t width = ilog2(MIN_ROLLOVER_SECS * freq);
+	int width = ilog2(MIN_ROLLOVER_SECS * freq);
 
 	width = clamp(width, 56, 64);
 	CVAL_MAX = GENMASK_ULL(width - 1, 0);

base-commit: a6ad54137af92535cfe32e19e5f3bc1bb7dbd383
-- 
2.51.0.536.g15c5d4f767-goog