perf/x86: Use macros to replace magic numbers in attr_rdpmc

Replace magic numbers in attr_rdpmc with macros to improve readability
and make their meanings clearer for users.

Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260114011750.350569-7-dapeng1.mi@linux.intel.com

Author: Dapeng Mi

arch/x86/events/core.c

@@ -2163,7 +2163,8 @@ static int __init init_hw_perf_events(void)
 
 	pr_cont("%s PMU driver.\n", x86_pmu.name);
 
-	x86_pmu.attr_rdpmc = 1; /* enable userspace RDPMC usage by default */
+	/* enable userspace RDPMC usage by default */
+	x86_pmu.attr_rdpmc = X86_USER_RDPMC_CONDITIONAL_ENABLE;
 
 	for (quirk = x86_pmu.quirks; quirk; quirk = quirk->next)
 		quirk->func();
@@ -2643,12 +2644,12 @@ static ssize_t set_attr_rdpmc(struct device *cdev,
 		 */
 		if (val == 0)
 			static_branch_inc(&rdpmc_never_available_key);
-		else if (x86_pmu.attr_rdpmc == 0)
+		else if (x86_pmu.attr_rdpmc == X86_USER_RDPMC_NEVER_ENABLE)
 			static_branch_dec(&rdpmc_never_available_key);
 
 		if (val == 2)
 			static_branch_inc(&rdpmc_always_available_key);
-		else if (x86_pmu.attr_rdpmc == 2)
+		else if (x86_pmu.attr_rdpmc == X86_USER_RDPMC_ALWAYS_ENABLE)
 			static_branch_dec(&rdpmc_always_available_key);
 
 		on_each_cpu(cr4_update_pce, NULL, 1);

arch/x86/events/intel/p6.c

@@ -243,7 +243,7 @@ static __init void p6_pmu_rdpmc_quirk(void)
 		 */
 		pr_warn("Userspace RDPMC support disabled due to a CPU erratum\n");
 		x86_pmu.attr_rdpmc_broken = 1;
-		x86_pmu.attr_rdpmc = 0;
+		x86_pmu.attr_rdpmc = X86_USER_RDPMC_NEVER_ENABLE;
 	}
 }
 

arch/x86/events/perf_event.h

@@ -187,6 +187,13 @@ struct amd_nb {
 	 (1ULL << PERF_REG_X86_R14)   | \
 	 (1ULL << PERF_REG_X86_R15))
 
+/* user space rdpmc control values */
+enum {
+	X86_USER_RDPMC_NEVER_ENABLE		= 0,
+	X86_USER_RDPMC_CONDITIONAL_ENABLE	= 1,
+	X86_USER_RDPMC_ALWAYS_ENABLE		= 2,
+};
+
 /*
  * Per register state.
  */