[Xen-changelog] [xen master] x86: package up context switch hook pointers

[patchbot@xxxxxxx]

commit ab914e04a62727b75782e401eaf2e8b72f717f61
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Feb 17 15:51:03 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Feb 17 15:51:03 2017 +0100

    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 three 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 expand
    schedule_tail() in the only two places invoking it, allowing the macro
    to be dropped.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/domain.c         | 43 +++++++++++++++++++++++++++++--------------
 xen/arch/x86/hvm/svm/svm.c    | 12 ++++++++----
 xen/arch/x86/hvm/vmx/vmx.c    | 11 +++++++----
 xen/include/asm-x86/current.h | 10 ----------
 xen/include/asm-x86/domain.h  | 11 ++++++-----
 5 files changed, 50 insertions(+), 37 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 130da29..7d3071e 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -425,16 +425,8 @@ 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);
 
@@ -641,8 +633,23 @@ int arch_domain_create(struct domain *d, unsigned int 
domcr_flags,
             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);
@@ -1996,7 +2003,7 @@ 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);
     }
 
     /*
@@ -2022,7 +2029,7 @@ 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);
@@ -2141,12 +2148,20 @@ void context_switch(struct vcpu *prev, struct vcpu 
*next)
     /* Ensure that the vcpu has an up-to-date time base. */
     update_vcpu_system_time(next);
 
-    schedule_tail(next);
+    /*
+     * Schedule tail *should* be a terminal function pointer, but leave a
+     * bug frame around just in case it returns, to save going back into the
+     * context switching code and leaving a far more subtle crash to diagnose.
+     */
+    nextd->arch.ctxt_switch->tail(next);
+    BUG();
 }
 
 void continue_running(struct vcpu *same)
 {
-    schedule_tail(same);
+    /* See the comment above. */
+    same->domain->arch.ctxt_switch->tail(same);
+    BUG();
 }
 
 int __sync_local_execstate(void)
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index f9bfbdd..894c457 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -1143,6 +1143,14 @@ 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;
 }
 
@@ -1154,10 +1162,6 @@ static int svm_vcpu_initialise(struct vcpu *v)
 {
     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 )
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 074939e..597d7ac 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -267,8 +267,15 @@ void vmx_pi_hooks_deassign(struct domain *d)
 
 static int vmx_domain_initialise(struct domain *d)
 {
+    static const struct arch_csw csw = {
+        .from = vmx_ctxt_switch_from,
+        .to   = vmx_ctxt_switch_to,
+        .tail = vmx_do_resume,
+    };
     int rc;
 
+    d->arch.ctxt_switch = &csw;
+
     if ( !has_vlapic(d) )
         return 0;
 
@@ -294,10 +301,6 @@ static int vmx_vcpu_initialise(struct vcpu *v)
 
     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;
-
     if ( (rc = vmx_create_vmcs(v)) != 0 )
     {
         dprintk(XENLOG_WARNING,
diff --git a/xen/include/asm-x86/current.h b/xen/include/asm-x86/current.h
index d2ee598..8984992 100644
--- a/xen/include/asm-x86/current.h
+++ b/xen/include/asm-x86/current.h
@@ -102,16 +102,6 @@ unsigned long get_stack_dump_bottom (unsigned long sp);
     })
 
 /*
- * 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.
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 9bb070f..2839a73 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -313,6 +313,12 @@ struct arch_domain
     } relmem;
     struct page_list_head relmem_list;
 
+    const struct arch_csw {
+        void (*from)(struct vcpu *);
+        void (*to)(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;
@@ -509,11 +515,6 @@ struct arch_vcpu
 
     unsigned long      flags; /* TF_ */
 
-    void (*schedule_tail) (struct vcpu *);
-
-    void (*ctxt_switch_from) (struct vcpu *);
-    void (*ctxt_switch_to) (struct vcpu *);
-
     struct vpmu_struct vpmu;
 
     /* Virtual Machine Extensions */
--
generated by git-patchbot for /home/xen/git/xen.git#master

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