They're all solely dependent on guest type, so we don't need to repeat
all the same four pointers in every vCPU control structure. Instead use
static const structures, and store pointers to them in the domain
control structure.

Since touching it anyway, take the opportunity and move schedule_tail()
into the only C file needing it.

Signed-off-by: Jan Beulich <jbeul...@suse.com>

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -426,16 +426,8 @@ int vcpu_initialise(struct vcpu *v)
         /* PV guests by default have a 100Hz ticker. */
         v->periodic_period = MILLISECS(10);
     }
-
-    v->arch.schedule_tail = continue_nonidle_domain;
-    v->arch.ctxt_switch_from = paravirt_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = paravirt_ctxt_switch_to;
-
-    if ( is_idle_domain(d) )
-    {
-        v->arch.schedule_tail = continue_idle_domain;
-        v->arch.cr3           = __pa(idle_pg_table);
-    }
+    else
+        v->arch.cr3 = __pa(idle_pg_table);
 
     v->arch.pv_vcpu.ctrlreg[4] = real_cr4_to_pv_guest_cr4(mmu_cr4_features);
 
@@ -642,8 +634,23 @@ int arch_domain_create(struct domain *d,
             goto fail;
     }
     else
+    {
+        static const struct arch_csw pv_csw = {
+            .from = paravirt_ctxt_switch_from,
+            .to   = paravirt_ctxt_switch_to,
+            .tail = continue_nonidle_domain,
+        };
+        static const struct arch_csw idle_csw = {
+            .from = paravirt_ctxt_switch_from,
+            .to   = paravirt_ctxt_switch_to,
+            .tail = continue_idle_domain,
+        };
+
+        d->arch.ctxt_switch = is_idle_domain(d) ? &idle_csw : &pv_csw;
+
         /* 64-bit PV guest by default. */
         d->arch.is_32bit_pv = d->arch.has_32bit_shinfo = 0;
+    }
 
     /* initialize default tsc behavior in case tools don't */
     tsc_set_info(d, TSC_MODE_DEFAULT, 0UL, 0, 0);
@@ -1997,7 +2004,7 @@ static void __context_switch(void)
     {
         memcpy(&p->arch.user_regs, stack_regs, CTXT_SWITCH_STACK_BYTES);
         vcpu_save_fpu(p);
-        p->arch.ctxt_switch_from(p);
+        pd->arch.ctxt_switch->from(p);
     }
 
     /*
@@ -2023,7 +2030,7 @@ static void __context_switch(void)
                 set_msr_xss(n->arch.hvm_vcpu.msr_xss);
         }
         vcpu_restore_fpu_eager(n);
-        n->arch.ctxt_switch_to(n);
+        nd->arch.ctxt_switch->to(n);
     }
 
     psr_ctxt_switch_to(nd);
@@ -2066,6 +2073,15 @@ static void __context_switch(void)
     per_cpu(curr_vcpu, cpu) = n;
 }
 
+/*
+ * Schedule tail *should* be a terminal function pointer, but leave a bugframe
+ * around just incase it returns, to save going back into the context
+ * switching code and leaving a far more subtle crash to diagnose.
+ */
+#define schedule_tail(vcpu) do {                          \
+        (((vcpu)->domain->arch.ctxt_switch->tail)(vcpu)); \
+        BUG();                                            \
+    } while (0)
 
 void context_switch(struct vcpu *prev, struct vcpu *next)
 {
@@ -2100,8 +2116,8 @@ void context_switch(struct vcpu *prev, s
 
     if ( (per_cpu(curr_vcpu, cpu) == next) )
     {
-        if ( next->arch.ctxt_switch_same )
-            next->arch.ctxt_switch_same(next);
+        if ( nextd->arch.ctxt_switch->same )
+            nextd->arch.ctxt_switch->same(next);
         local_irq_enable();
     }
     else if ( is_idle_domain(nextd) && cpu_online(cpu) )
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1144,6 +1144,14 @@ void svm_host_osvw_init()
 
 static int svm_domain_initialise(struct domain *d)
 {
+    static const struct arch_csw csw = {
+        .from = svm_ctxt_switch_from,
+        .to   = svm_ctxt_switch_to,
+        .tail = svm_do_resume,
+    };
+
+    d->arch.ctxt_switch = &csw;
+
     return 0;
 }
 
@@ -1155,10 +1163,6 @@ static int svm_vcpu_initialise(struct vc
 {
     int rc;
 
-    v->arch.schedule_tail    = svm_do_resume;
-    v->arch.ctxt_switch_from = svm_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = svm_ctxt_switch_to;
-
     v->arch.hvm_svm.launch_core = -1;
 
     if ( (rc = svm_create_vmcb(v)) != 0 )
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -268,8 +268,16 @@ void vmx_pi_hooks_deassign(struct domain
 
 static int vmx_domain_initialise(struct domain *d)
 {
+    static const struct arch_csw csw = {
+        .from = vmx_ctxt_switch_from,
+        .to   = vmx_ctxt_switch_to,
+        .same = vmx_vmcs_reload,
+        .tail = vmx_do_resume,
+    };
     int rc;
 
+    d->arch.ctxt_switch = &csw;
+
     if ( !has_vlapic(d) )
         return 0;
 
@@ -295,11 +303,6 @@ static int vmx_vcpu_initialise(struct vc
 
     INIT_LIST_HEAD(&v->arch.hvm_vmx.pi_blocking.list);
 
-    v->arch.schedule_tail    = vmx_do_resume;
-    v->arch.ctxt_switch_from = vmx_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = vmx_ctxt_switch_to;
-    v->arch.ctxt_switch_same = vmx_vmcs_reload;
-
     if ( (rc = vmx_create_vmcs(v)) != 0 )
     {
         dprintk(XENLOG_WARNING,
--- a/xen/include/asm-x86/current.h
+++ b/xen/include/asm-x86/current.h
@@ -103,16 +103,6 @@ unsigned long get_stack_dump_bottom (uns
     })
 
 /*
- * Schedule tail *should* be a terminal function pointer, but leave a bugframe
- * around just incase it returns, to save going back into the context
- * switching code and leaving a far more subtle crash to diagnose.
- */
-#define schedule_tail(vcpu) do {                \
-        (((vcpu)->arch.schedule_tail)(vcpu));   \
-        BUG();                                  \
-    } while (0)
-
-/*
  * Which VCPU's state is currently running on each CPU?
  * This is not necesasrily the same as 'current' as a CPU may be
  * executing a lazy state switch.
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -314,6 +314,13 @@ struct arch_domain
     } relmem;
     struct page_list_head relmem_list;
 
+    const struct arch_csw {
+        void (*from)(struct vcpu *);
+        void (*to)(struct vcpu *);
+        void (*same)(struct vcpu *);
+        void (*tail)(struct vcpu *);
+    } *ctxt_switch;
+
     /* nestedhvm: translate l2 guest physical to host physical */
     struct p2m_domain *nested_p2m[MAX_NESTEDP2M];
     mm_lock_t nested_p2m_lock;
@@ -510,12 +517,6 @@ struct arch_vcpu
 
     unsigned long      flags; /* TF_ */
 
-    void (*schedule_tail) (struct vcpu *);
-
-    void (*ctxt_switch_from) (struct vcpu *);
-    void (*ctxt_switch_to) (struct vcpu *);
-    void (*ctxt_switch_same) (struct vcpu *);
-
     struct vpmu_struct vpmu;
 
     /* Virtual Machine Extensions */


x86: package up context switch hook pointers

They're all solely dependent on guest type, so we don't need to repeat
all the same four pointers in every vCPU control structure. Instead use
static const structures, and store pointers to them in the domain
control structure.

Since touching it anyway, take the opportunity and move schedule_tail()
into the only C file needing it.

Signed-off-by: Jan Beulich <jbeul...@suse.com>

--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -426,16 +426,8 @@ int vcpu_initialise(struct vcpu *v)
         /* PV guests by default have a 100Hz ticker. */
         v->periodic_period = MILLISECS(10);
     }
-
-    v->arch.schedule_tail = continue_nonidle_domain;
-    v->arch.ctxt_switch_from = paravirt_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = paravirt_ctxt_switch_to;
-
-    if ( is_idle_domain(d) )
-    {
-        v->arch.schedule_tail = continue_idle_domain;
-        v->arch.cr3           = __pa(idle_pg_table);
-    }
+    else
+        v->arch.cr3 = __pa(idle_pg_table);
 
     v->arch.pv_vcpu.ctrlreg[4] = real_cr4_to_pv_guest_cr4(mmu_cr4_features);
 
@@ -642,8 +634,23 @@ int arch_domain_create(struct domain *d,
             goto fail;
     }
     else
+    {
+        static const struct arch_csw pv_csw = {
+            .from = paravirt_ctxt_switch_from,
+            .to   = paravirt_ctxt_switch_to,
+            .tail = continue_nonidle_domain,
+        };
+        static const struct arch_csw idle_csw = {
+            .from = paravirt_ctxt_switch_from,
+            .to   = paravirt_ctxt_switch_to,
+            .tail = continue_idle_domain,
+        };
+
+        d->arch.ctxt_switch = is_idle_domain(d) ? &idle_csw : &pv_csw;
+
         /* 64-bit PV guest by default. */
         d->arch.is_32bit_pv = d->arch.has_32bit_shinfo = 0;
+    }
 
     /* initialize default tsc behavior in case tools don't */
     tsc_set_info(d, TSC_MODE_DEFAULT, 0UL, 0, 0);
@@ -1997,7 +2004,7 @@ static void __context_switch(void)
     {
         memcpy(&p->arch.user_regs, stack_regs, CTXT_SWITCH_STACK_BYTES);
         vcpu_save_fpu(p);
-        p->arch.ctxt_switch_from(p);
+        pd->arch.ctxt_switch->from(p);
     }
 
     /*
@@ -2023,7 +2030,7 @@ static void __context_switch(void)
                 set_msr_xss(n->arch.hvm_vcpu.msr_xss);
         }
         vcpu_restore_fpu_eager(n);
-        n->arch.ctxt_switch_to(n);
+        nd->arch.ctxt_switch->to(n);
     }
 
     psr_ctxt_switch_to(nd);
@@ -2066,6 +2073,15 @@ static void __context_switch(void)
     per_cpu(curr_vcpu, cpu) = n;
 }
 
+/*
+ * Schedule tail *should* be a terminal function pointer, but leave a bugframe
+ * around just incase it returns, to save going back into the context
+ * switching code and leaving a far more subtle crash to diagnose.
+ */
+#define schedule_tail(vcpu) do {                          \
+        (((vcpu)->domain->arch.ctxt_switch->tail)(vcpu)); \
+        BUG();                                            \
+    } while (0)
 
 void context_switch(struct vcpu *prev, struct vcpu *next)
 {
@@ -2100,8 +2116,8 @@ void context_switch(struct vcpu *prev, s
 
     if ( (per_cpu(curr_vcpu, cpu) == next) )
     {
-        if ( next->arch.ctxt_switch_same )
-            next->arch.ctxt_switch_same(next);
+        if ( nextd->arch.ctxt_switch->same )
+            nextd->arch.ctxt_switch->same(next);
         local_irq_enable();
     }
     else if ( is_idle_domain(nextd) && cpu_online(cpu) )
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1144,6 +1144,14 @@ void svm_host_osvw_init()
 
 static int svm_domain_initialise(struct domain *d)
 {
+    static const struct arch_csw csw = {
+        .from = svm_ctxt_switch_from,
+        .to   = svm_ctxt_switch_to,
+        .tail = svm_do_resume,
+    };
+
+    d->arch.ctxt_switch = &csw;
+
     return 0;
 }
 
@@ -1155,10 +1163,6 @@ static int svm_vcpu_initialise(struct vc
 {
     int rc;
 
-    v->arch.schedule_tail    = svm_do_resume;
-    v->arch.ctxt_switch_from = svm_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = svm_ctxt_switch_to;
-
     v->arch.hvm_svm.launch_core = -1;
 
     if ( (rc = svm_create_vmcb(v)) != 0 )
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -268,8 +268,16 @@ void vmx_pi_hooks_deassign(struct domain
 
 static int vmx_domain_initialise(struct domain *d)
 {
+    static const struct arch_csw csw = {
+        .from = vmx_ctxt_switch_from,
+        .to   = vmx_ctxt_switch_to,
+        .same = vmx_vmcs_reload,
+        .tail = vmx_do_resume,
+    };
     int rc;
 
+    d->arch.ctxt_switch = &csw;
+
     if ( !has_vlapic(d) )
         return 0;
 
@@ -295,11 +303,6 @@ static int vmx_vcpu_initialise(struct vc
 
     INIT_LIST_HEAD(&v->arch.hvm_vmx.pi_blocking.list);
 
-    v->arch.schedule_tail    = vmx_do_resume;
-    v->arch.ctxt_switch_from = vmx_ctxt_switch_from;
-    v->arch.ctxt_switch_to   = vmx_ctxt_switch_to;
-    v->arch.ctxt_switch_same = vmx_vmcs_reload;
-
     if ( (rc = vmx_create_vmcs(v)) != 0 )
     {
         dprintk(XENLOG_WARNING,
--- a/xen/include/asm-x86/current.h
+++ b/xen/include/asm-x86/current.h
@@ -103,16 +103,6 @@ unsigned long get_stack_dump_bottom (uns
     })
 
 /*
- * Schedule tail *should* be a terminal function pointer, but leave a bugframe
- * around just incase it returns, to save going back into the context
- * switching code and leaving a far more subtle crash to diagnose.
- */
-#define schedule_tail(vcpu) do {                \
-        (((vcpu)->arch.schedule_tail)(vcpu));   \
-        BUG();                                  \
-    } while (0)
-
-/*
  * Which VCPU's state is currently running on each CPU?
  * This is not necesasrily the same as 'current' as a CPU may be
  * executing a lazy state switch.
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -314,6 +314,13 @@ struct arch_domain
     } relmem;
     struct page_list_head relmem_list;
 
+    const struct arch_csw {
+        void (*from)(struct vcpu *);
+        void (*to)(struct vcpu *);
+        void (*same)(struct vcpu *);
+        void (*tail)(struct vcpu *);
+    } *ctxt_switch;
+
     /* nestedhvm: translate l2 guest physical to host physical */
     struct p2m_domain *nested_p2m[MAX_NESTEDP2M];
     mm_lock_t nested_p2m_lock;
@@ -510,12 +517,6 @@ struct arch_vcpu
 
     unsigned long      flags; /* TF_ */
 
-    void (*schedule_tail) (struct vcpu *);
-
-    void (*ctxt_switch_from) (struct vcpu *);
-    void (*ctxt_switch_to) (struct vcpu *);
-    void (*ctxt_switch_same) (struct vcpu *);
-
     struct vpmu_struct vpmu;
 
     /* Virtual Machine Extensions */
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