x86/levelling: Pass a vcpu rather than a domain to ctxt_switch_levelling()

A subsequent change needs to special-case OSXSAVE handling, which is per-vcpu
rather than per-domain.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/cpu/amd.c

@@ -203,9 +203,10 @@ static void __init noinline probe_masking_msrs(void)
  * used to context switch to the default host state (by the cpu bringup-code,
  * crash path, etc).
  */
-static void amd_ctxt_switch_levelling(const struct domain *nextd)
+static void amd_ctxt_switch_levelling(const struct vcpu *next)
 {
 	struct cpuidmasks *these_masks = &this_cpu(cpuidmasks);
+	const struct domain *nextd = next ? next->domain : NULL;
 	const struct cpuidmasks *masks =
 		(nextd && is_pv_domain(nextd) && nextd->arch.pv_domain.cpuidmasks)
 		? nextd->arch.pv_domain.cpuidmasks : &cpuidmask_defaults;

xen/arch/x86/cpu/common.c

@@ -90,11 +90,11 @@ static const struct cpu_dev default_cpu = {
 };
 static const struct cpu_dev *this_cpu = &default_cpu;
 
-static void default_ctxt_switch_levelling(const struct domain *nextd)
+static void default_ctxt_switch_levelling(const struct vcpu *next)
 {
 	/* Nop */
 }
-void (* __read_mostly ctxt_switch_levelling)(const struct domain *nextd) =
+void (* __read_mostly ctxt_switch_levelling)(const struct vcpu *next) =
 	default_ctxt_switch_levelling;
 
 bool_t opt_cpu_info;

xen/arch/x86/cpu/intel.c

@@ -151,9 +151,10 @@ static void __init probe_masking_msrs(void)
  * used to context switch to the default host state (by the cpu bringup-code,
  * crash path, etc).
  */
-static void intel_ctxt_switch_levelling(const struct domain *nextd)
+static void intel_ctxt_switch_levelling(const struct vcpu *next)
 {
 	struct cpuidmasks *these_masks = &this_cpu(cpuidmasks);
+	const struct domain *nextd = next ? next->domain : NULL;
 	const struct cpuidmasks *masks;
 
 	if (cpu_has_cpuid_faulting) {

xen/arch/x86/domain.c

@@ -2130,7 +2130,7 @@ void context_switch(struct vcpu *prev, struct vcpu *next)
             load_segments(next);
         }
 
-        ctxt_switch_levelling(nextd);
+        ctxt_switch_levelling(next);
     }
 
     context_saved(prev);

xen/include/asm-x86/processor.h

@@ -217,7 +217,7 @@ extern struct cpuinfo_x86 boot_cpu_data;
 extern struct cpuinfo_x86 cpu_data[];
 #define current_cpu_data cpu_data[smp_processor_id()]
 
-extern void (*ctxt_switch_levelling)(const struct domain *nextd);
+extern void (*ctxt_switch_levelling)(const struct vcpu *next);
 
 extern u64 host_pat;
 extern bool_t opt_cpu_info;