[xen staging] x86/vPMU: move vpmu_ops to .init.data

[patchbot@xxxxxxx]

commit 75a16d4c5f16c611687a4460dfae23909588f3fa
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Dec 3 11:22:03 2021 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Dec 3 11:22:03 2021 +0100

    x86/vPMU: move vpmu_ops to .init.data
    
    Both vendors' code populates all hooks, so there's no need to have any
    NULL checks before invoking the hook functions. With that the only
    remaining uses of the object are in alternative_{,v}call(), i.e. none
    after alternatives patching.
    
    In vpmu_arch_initialise() the check gets replaced by an opt_vpmu_enabled
    one, as I couldn't convince myself that the pre-existing checks would be
    sufficient to cover all possible cases.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/cpu/vpmu.c | 54 ++++++++++++++++++-------------------------------
 1 file changed, 20 insertions(+), 34 deletions(-)

diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index 64a8f45c16..7fd69a2a58 100644
--- a/xen/arch/x86/cpu/vpmu.c
+++ b/xen/arch/x86/cpu/vpmu.c
@@ -49,7 +49,7 @@ CHECK_pmu_params;
 static unsigned int __read_mostly opt_vpmu_enabled;
 unsigned int __read_mostly vpmu_mode = XENPMU_MODE_OFF;
 unsigned int __read_mostly vpmu_features = 0;
-static struct arch_vpmu_ops __read_mostly vpmu_ops;
+static struct arch_vpmu_ops __initdata vpmu_ops;
 
 static DEFINE_SPINLOCK(vpmu_lock);
 static unsigned vpmu_count;
@@ -136,12 +136,10 @@ int vpmu_do_msr(unsigned int msr, uint64_t *msr_content,
     if ( !vpmu_is_set(vpmu, VPMU_INITIALIZED) )
         goto nop;
 
-    if ( is_write && vpmu_ops.do_wrmsr )
+    if ( is_write )
         ret = alternative_call(vpmu_ops.do_wrmsr, msr, *msr_content, 
supported);
-    else if ( !is_write && vpmu_ops.do_rdmsr )
-        ret = alternative_call(vpmu_ops.do_rdmsr, msr, msr_content);
     else
-        goto nop;
+        ret = alternative_call(vpmu_ops.do_rdmsr, msr, msr_content);
 
     /*
      * We may have received a PMU interrupt while handling MSR access
@@ -375,7 +373,7 @@ void vpmu_save(struct vcpu *v)
 int vpmu_load(struct vcpu *v, bool_t from_guest)
 {
     struct vpmu_struct *vpmu = vcpu_vpmu(v);
-    int pcpu = smp_processor_id();
+    int pcpu = smp_processor_id(), ret;
     struct vcpu *prev = NULL;
 
     if ( !vpmu_is_set(vpmu, VPMU_CONTEXT_ALLOCATED) )
@@ -423,21 +421,13 @@ int vpmu_load(struct vcpu *v, bool_t from_guest)
          vpmu_is_set(vpmu, VPMU_CACHED)) )
         return 0;
 
-    if ( vpmu_ops.arch_vpmu_load )
-    {
-        int ret;
-
-        apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
-        /* Arch code needs to set VPMU_CONTEXT_LOADED */
-        ret = alternative_call(vpmu_ops.arch_vpmu_load, v, from_guest);
-        if ( ret )
-        {
-            apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc | APIC_LVT_MASKED);
-            return ret;
-        }
-    }
+    apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc);
+    /* Arch code needs to set VPMU_CONTEXT_LOADED */
+    ret = alternative_call(vpmu_ops.arch_vpmu_load, v, from_guest);
+    if ( ret )
+        apic_write(APIC_LVTPC, vpmu->hw_lapic_lvtpc | APIC_LVT_MASKED);
 
-    return 0;
+    return ret;
 }
 
 static int vpmu_arch_initialise(struct vcpu *v)
@@ -458,7 +448,7 @@ static int vpmu_arch_initialise(struct vcpu *v)
     if ( !vpmu_available(v) || vpmu_mode == XENPMU_MODE_OFF )
         return 0;
 
-    if ( !vpmu_ops.initialise )
+    if ( !opt_vpmu_enabled )
     {
         if ( vpmu_mode != XENPMU_MODE_OFF )
         {
@@ -564,18 +554,15 @@ static void vpmu_arch_destroy(struct vcpu *v)
         on_selected_cpus(cpumask_of(vpmu->last_pcpu),
                          vpmu_clear_last, v, 1);
 
-    if ( vpmu_ops.arch_vpmu_destroy )
-    {
-        /*
-         * Unload VPMU first if VPMU_CONTEXT_LOADED being set.
-         * This will stop counters.
-         */
-        if ( vpmu_is_set(vpmu, VPMU_CONTEXT_LOADED) )
-            on_selected_cpus(cpumask_of(vcpu_vpmu(v)->last_pcpu),
-                             vpmu_save_force, v, 1);
+    /*
+     * Unload VPMU first if VPMU_CONTEXT_LOADED being set.
+     * This will stop counters.
+     */
+    if ( vpmu_is_set(vpmu, VPMU_CONTEXT_LOADED) )
+        on_selected_cpus(cpumask_of(vcpu_vpmu(v)->last_pcpu),
+                         vpmu_save_force, v, 1);
 
-         alternative_vcall(vpmu_ops.arch_vpmu_destroy, v);
-    }
+    alternative_vcall(vpmu_ops.arch_vpmu_destroy, v);
 
     vpmu_reset(vpmu, VPMU_CONTEXT_ALLOCATED);
 }
@@ -681,8 +668,7 @@ static void pvpmu_finish(struct domain *d, xen_pmu_params_t 
*params)
 /* Dump some vpmu information to console. Used in keyhandler dump_domains(). */
 void vpmu_dump(struct vcpu *v)
 {
-    if ( vpmu_is_set(vcpu_vpmu(v), VPMU_INITIALIZED) &&
-         vpmu_ops.arch_vpmu_dump )
+    if ( vpmu_is_set(vcpu_vpmu(v), VPMU_INITIALIZED) )
         alternative_vcall(vpmu_ops.arch_vpmu_dump, v);
 }
 
--
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