Possibly many slots of it may be unused (all of them when the HWP or CPPC
drivers are in use), as it's always strictly associated with the CPU
recorded in a policy (irrespective of that CPU intermediately being taken
offline). It is shared by all CPUs sharing a policy. We could therefore
put the respective pointers in struct cpufreq_policy, but even that level
of indirection is pointless. Embed the driver data structure directly in
the policy one.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
---
v2: Re-base, use union.

--- a/xen/arch/x86/acpi/cpufreq/acpi.c
+++ b/xen/arch/x86/acpi/cpufreq/acpi.c
@@ -174,17 +174,18 @@ static u32 get_cur_val(const cpumask_t *
         return 0;
 
     policy = per_cpu(cpufreq_cpu_policy, cpu);
-    if (!policy || !cpufreq_drv_data[policy->cpu])
+    if ( !policy )
         return 0;
 
-    switch (cpufreq_drv_data[policy->cpu]->arch_cpu_flags) {
+    switch ( policy->drv_data.acpi.arch_cpu_flags )
+    {
     case SYSTEM_INTEL_MSR_CAPABLE:
         cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
         cmd.addr.msr.reg = MSR_IA32_PERF_STATUS;
         break;
     case SYSTEM_IO_CAPABLE:
         cmd.type = SYSTEM_IO_CAPABLE;
-        perf = cpufreq_drv_data[policy->cpu]->acpi_data;
+        perf = policy->drv_data.acpi.acpi_data;
         cmd.addr.io.port = perf->control_register.address;
         cmd.addr.io.bit_width = perf->control_register.bit_width;
         break;
@@ -210,9 +211,8 @@ static unsigned int cf_check get_cur_fre
     if (!policy)
         return 0;
 
-    data = cpufreq_drv_data[policy->cpu];
-    if (unlikely(data == NULL ||
-        data->acpi_data == NULL || data->freq_table == NULL))
+    data = &policy->drv_data.acpi;
+    if ( !data->acpi_data || !data->freq_table )
         return 0;
 
     return extract_freq(get_cur_val(cpumask_of(cpu)), data);
@@ -252,7 +252,7 @@ static int cf_check acpi_cpufreq_target(
     struct cpufreq_policy *policy,
     unsigned int target_freq, unsigned int relation)
 {
-    struct acpi_cpufreq_data *data = cpufreq_drv_data[policy->cpu];
+    struct acpi_cpufreq_data *data = &policy->drv_data.acpi;
     struct processor_performance *perf;
     struct cpufreq_freqs freqs;
     cpumask_t online_policy_cpus;
@@ -262,10 +262,8 @@ static int cf_check acpi_cpufreq_target(
     unsigned int j;
     int result = 0;
 
-    if (unlikely(data == NULL ||
-        data->acpi_data == NULL || data->freq_table == NULL)) {
+    if ( !data->acpi_data || !data->freq_table )
         return -ENODEV;
-    }
 
     if (policy->turbo == CPUFREQ_TURBO_DISABLED)
         if (target_freq > policy->cpuinfo.second_max_freq)
@@ -331,11 +329,9 @@ static int cf_check acpi_cpufreq_target(
 
 static int cf_check acpi_cpufreq_verify(struct cpufreq_policy *policy)
 {
-    struct acpi_cpufreq_data *data;
     struct processor_performance *perf;
 
-    if (!policy || !(data = cpufreq_drv_data[policy->cpu]) ||
-        !processor_pminfo[policy->cpu])
+    if ( !policy || !processor_pminfo[policy->cpu] )
         return -EINVAL;
 
     perf = &processor_pminfo[policy->cpu]->perf;
@@ -343,7 +339,8 @@ static int cf_check acpi_cpufreq_verify(
     cpufreq_verify_within_limits(policy, 0,
         perf->states[perf->platform_limit].core_frequency * 1000);
 
-    return cpufreq_frequency_table_verify(policy, data->freq_table);
+    return cpufreq_frequency_table_verify(policy,
+                                          policy->drv_data.acpi.freq_table);
 }
 
 static unsigned long
@@ -379,17 +376,11 @@ static int cf_check acpi_cpufreq_cpu_ini
     unsigned int i;
     unsigned int valid_states = 0;
     unsigned int cpu = policy->cpu;
-    struct acpi_cpufreq_data *data;
+    struct acpi_cpufreq_data *data = &policy->drv_data.acpi;
     unsigned int result = 0;
     struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
     struct processor_performance *perf;
 
-    data = xzalloc(struct acpi_cpufreq_data);
-    if (!data)
-        return -ENOMEM;
-
-    cpufreq_drv_data[cpu] = data;
-
     data->acpi_data = &processor_pminfo[cpu]->perf;
 
     perf = data->acpi_data;
@@ -406,23 +397,18 @@ static int cf_check acpi_cpufreq_cpu_ini
         if (cpufreq_verbose)
             printk("xen_pminfo: @acpi_cpufreq_cpu_init,"
                    "HARDWARE addr space\n");
-        if (!cpu_has(c, X86_FEATURE_EIST)) {
-            result = -ENODEV;
-            goto err_unreg;
-        }
+        if ( !cpu_has(c, X86_FEATURE_EIST) )
+            return -ENODEV;
         data->arch_cpu_flags = SYSTEM_INTEL_MSR_CAPABLE;
         break;
     default:
-        result = -ENODEV;
-        goto err_unreg;
+        return -ENODEV;
     }
 
     data->freq_table = xmalloc_array(struct cpufreq_frequency_table,
                                     (perf->state_count+1));
-    if (!data->freq_table) {
-        result = -ENOMEM;
-        goto err_unreg;
-    }
+    if ( !data->freq_table )
+        return -ENOMEM;
 
     /* detect transition latency */
     policy->cpuinfo.transition_latency = 0;
@@ -480,23 +466,14 @@ static int cf_check acpi_cpufreq_cpu_ini
     return result;
 
 err_freqfree:
-    xfree(data->freq_table);
-err_unreg:
-    xfree(data);
-    cpufreq_drv_data[cpu] = NULL;
+    XFREE(data->freq_table);
 
     return result;
 }
 
 static int cf_check acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 {
-    struct acpi_cpufreq_data *data = cpufreq_drv_data[policy->cpu];
-
-    if (data) {
-        cpufreq_drv_data[policy->cpu] = NULL;
-        xfree(data->freq_table);
-        xfree(data);
-    }
+    XFREE(policy->drv_data.acpi.freq_table);
 
     return 0;
 }
--- a/xen/arch/x86/acpi/cpufreq/cpufreq.c
+++ b/xen/arch/x86/acpi/cpufreq/cpufreq.c
@@ -35,8 +35,6 @@
 
 #include <acpi/cpufreq/cpufreq.h>
 
-struct acpi_cpufreq_data *cpufreq_drv_data[NR_CPUS];
-
 struct perf_pair {
     union {
         struct {
--- a/xen/arch/x86/acpi/cpufreq/powernow.c
+++ b/xen/arch/x86/acpi/cpufreq/powernow.c
@@ -84,16 +84,14 @@ static int cf_check powernow_cpufreq_tar
     struct cpufreq_policy *policy,
     unsigned int target_freq, unsigned int relation)
 {
-    struct acpi_cpufreq_data *data = cpufreq_drv_data[policy->cpu];
+    struct acpi_cpufreq_data *data = &policy->drv_data.acpi;
     struct processor_performance *perf;
     unsigned int next_state; /* Index into freq_table */
     unsigned int next_perf_state; /* Index into perf table */
     int result;
 
-    if (unlikely(data == NULL ||
-        data->acpi_data == NULL || data->freq_table == NULL)) {
+    if ( !data->acpi_data || !data->freq_table )
         return -ENODEV;
-    }
 
     perf = data->acpi_data;
     result = cpufreq_frequency_table_target(policy,
@@ -187,11 +185,9 @@ static void cf_check get_cpu_data(void *
 
 static int cf_check powernow_cpufreq_verify(struct cpufreq_policy *policy)
 {
-    struct acpi_cpufreq_data *data;
     struct processor_performance *perf;
 
-    if (!policy || !(data = cpufreq_drv_data[policy->cpu]) ||
-        !processor_pminfo[policy->cpu])
+    if ( !policy || !processor_pminfo[policy->cpu] )
         return -EINVAL;
 
     perf = &processor_pminfo[policy->cpu]->perf;
@@ -199,7 +195,8 @@ static int cf_check powernow_cpufreq_ver
     cpufreq_verify_within_limits(policy, 0, 
         perf->states[perf->platform_limit].core_frequency * 1000);
 
-    return cpufreq_frequency_table_verify(policy, data->freq_table);
+    return cpufreq_frequency_table_verify(policy,
+                                          policy->drv_data.acpi.freq_table);
 }
 
 static int cf_check powernow_cpufreq_cpu_init(struct cpufreq_policy *policy)
@@ -207,18 +204,12 @@ static int cf_check powernow_cpufreq_cpu
     unsigned int i;
     unsigned int valid_states = 0;
     unsigned int cpu = policy->cpu;
-    struct acpi_cpufreq_data *data;
+    struct acpi_cpufreq_data *data = &policy->drv_data.acpi;
     unsigned int result = 0;
     struct processor_performance *perf;
     struct amd_cpu_data info;
     struct cpuinfo_x86 *c = &cpu_data[policy->cpu];
 
-    data = xzalloc(struct acpi_cpufreq_data);
-    if (!data)
-        return -ENOMEM;
-
-    cpufreq_drv_data[cpu] = data;
-
     data->acpi_data = &processor_pminfo[cpu]->perf;
 
     info.perf = perf = data->acpi_data;
@@ -230,8 +221,7 @@ static int cf_check powernow_cpufreq_cpu
         if (cpumask_weight(policy->cpus) != 1) {
             printk(XENLOG_WARNING "Unsupported sharing type %d (%u CPUs)\n",
                    policy->shared_type, cpumask_weight(policy->cpus));
-            result = -ENODEV;
-            goto err_unreg;
+            return -ENODEV;
         }
     } else {
         cpumask_copy(policy->cpus, cpumask_of(cpu));
@@ -240,21 +230,16 @@ static int cf_check powernow_cpufreq_cpu
     /* capability check */
     if (perf->state_count <= 1) {
         printk("No P-States\n");
-        result = -ENODEV;
-        goto err_unreg;
+        return -ENODEV;
     }
 
-    if (perf->control_register.space_id != perf->status_register.space_id) {
-        result = -ENODEV;
-        goto err_unreg;
-    }
+    if ( perf->control_register.space_id != perf->status_register.space_id )
+        return -ENODEV;
 
     data->freq_table = xmalloc_array(struct cpufreq_frequency_table, 
                                     (perf->state_count+1));
-    if (!data->freq_table) {
-        result = -ENOMEM;
-        goto err_unreg;
-    }
+    if ( !data->freq_table )
+        return -ENOMEM;
 
     /* detect transition latency */
     policy->cpuinfo.transition_latency = 0;
@@ -300,23 +285,14 @@ static int cf_check powernow_cpufreq_cpu
     return result;
 
 err_freqfree:
-    xfree(data->freq_table);
-err_unreg:
-    xfree(data);
-    cpufreq_drv_data[cpu] = NULL;
+    XFREE(data->freq_table);
 
     return result;
 }
 
 static int cf_check powernow_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 {
-    struct acpi_cpufreq_data *data = cpufreq_drv_data[policy->cpu];
-
-    if (data) {
-        cpufreq_drv_data[policy->cpu] = NULL;
-        xfree(data->freq_table);
-        xfree(data);
-    }
+    XFREE(policy->drv_data.acpi.freq_table);
 
     return 0;
 }
--- a/xen/include/acpi/cpufreq/cpufreq.h
+++ b/xen/include/acpi/cpufreq/cpufreq.h
@@ -38,8 +38,6 @@ struct acpi_cpufreq_data {
     unsigned int arch_cpu_flags;
 };
 
-extern struct acpi_cpufreq_data *cpufreq_drv_data[NR_CPUS];
-
 struct cpufreq_cpuinfo {
     unsigned int        max_freq;
     unsigned int        second_max_freq;    /* P1 if Turbo Mode is on */
@@ -82,6 +80,10 @@ struct cpufreq_policy {
                                  * -1 for disable, 1 for enabled
                                  * See CPUFREQ_TURBO_* below for defines */
     unsigned int        policy; /* CPUFREQ_POLICY_* */
+
+    union {
+        struct acpi_cpufreq_data acpi;
+    }                   drv_data;
 };
 DECLARE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_policy);

On 2026-01-22 04:42, Jan Beulich wrote:
> Possibly many slots of it may be unused (all of them when the HWP or CPPC
> drivers are in use), as it's always strictly associated with the CPU
> recorded in a policy (irrespective of that CPU intermediately being taken
> offline). It is shared by all CPUs sharing a policy. We could therefore
> put the respective pointers in struct cpufreq_policy, but even that level
> of indirection is pointless. Embed the driver data structure directly in
> the policy one.
> 
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Jason Andryuk <jason.andryuk@amd.com>