[PATCH v3] x86/vlapic: call vmx_vlapic_msr_changed through an hvm_function callback

[Xenia Ragiadakou <burzalodowa@xxxxxxxxx>]

APIC virtualization support is currently implemented only for Intel VT-x.
To aid future work on separating AMD-V from Intel VT-x code, instead of
calling directly vmx_vlapic_msr_changed() from common hvm code, add a stub
to the hvm_function_table, named update_vlapic_mode, and create a wrapper
function, called hvm_vlapic_mode(), to be used by common hvm code.

After the change above, do not include header asm/hvm/vmx/vmx.h as it is
not required anymore and resolve subsequent build errors for implicit
declaration of functions ‘TRACE_2_LONG_3D’ and ‘TRC_PAR_LONG’ by including
missing asm/hvm/trace.h header.

No functional change intended.

Signed-off-by: Xenia Ragiadakou <burzalodowa@xxxxxxxxx>
---

Changes in v3:
  - add cf_check attribute in both the function declaration and definition of
    vmx_vlapic_msr_changed since it is used as callback, bug reported by Jan
  - initialize update_vlapic_mode in the vmx_function_table initializer to
    keep unconditionally initialized cbs in a single place, reported by Jan

 xen/arch/x86/hvm/vlapic.c              | 6 +++---
 xen/arch/x86/hvm/vmx/vmx.c             | 3 ++-
 xen/arch/x86/include/asm/hvm/hvm.h     | 7 +++++++
 xen/arch/x86/include/asm/hvm/vmx/vmx.h | 2 +-
 4 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index eb32f12e2d..dc93b5e930 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -37,8 +37,8 @@
 #include <asm/hvm/hvm.h>
 #include <asm/hvm/io.h>
 #include <asm/hvm/support.h>
-#include <asm/hvm/vmx/vmx.h>
 #include <asm/hvm/nestedhvm.h>
+#include <asm/hvm/trace.h>
 #include <asm/hvm/viridian.h>
 #include <public/hvm/ioreq.h>
 #include <public/hvm/params.h>
@@ -1165,7 +1165,7 @@ int guest_wrmsr_apic_base(struct vcpu *v, uint64_t value)
     if ( vlapic_x2apic_mode(vlapic) )
         set_x2apic_id(vlapic);
 
-    vmx_vlapic_msr_changed(vlapic_vcpu(vlapic));
+    hvm_update_vlapic_mode(vlapic_vcpu(vlapic));
 
     HVM_DBG_LOG(DBG_LEVEL_VLAPIC,
                 "apic base msr is 0x%016"PRIx64, vlapic->hw.apic_base_msr);
@@ -1561,7 +1561,7 @@ static int cf_check lapic_load_hidden(struct domain *d, 
hvm_domain_context_t *h)
          unlikely(vlapic_x2apic_mode(s)) )
         return -EINVAL;
 
-    vmx_vlapic_msr_changed(v);
+    hvm_update_vlapic_mode(v);
 
     return 0;
 }
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 270bc98195..0ec33bcc18 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -2763,6 +2763,7 @@ static struct hvm_function_table __initdata_cf_clobber 
vmx_function_table = {
     .nhvm_vcpu_vmexit_event = nvmx_vmexit_event,
     .nhvm_intr_blocked    = nvmx_intr_blocked,
     .nhvm_domain_relinquish_resources = nvmx_domain_relinquish_resources,
+    .update_vlapic_mode = vmx_vlapic_msr_changed,
     .nhvm_hap_walk_L1_p2m = nvmx_hap_walk_L1_p2m,
     .enable_msr_interception = vmx_enable_msr_interception,
     .altp2m_vcpu_update_p2m = vmx_vcpu_update_eptp,
@@ -3472,7 +3473,7 @@ static void vmx_install_vlapic_mapping(struct vcpu *v)
     vmx_vmcs_exit(v);
 }
 
-void vmx_vlapic_msr_changed(struct vcpu *v)
+void cf_check vmx_vlapic_msr_changed(struct vcpu *v)
 {
     int virtualize_x2apic_mode;
     struct vlapic *vlapic = vcpu_vlapic(v);
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h 
b/xen/arch/x86/include/asm/hvm/hvm.h
index 80e4565bd2..43d3fc2498 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -217,6 +217,7 @@ struct hvm_function_table {
     void (*handle_eoi)(uint8_t vector, int isr);
     int (*pi_update_irte)(const struct vcpu *v, const struct pirq *pirq,
                           uint8_t gvec);
+    void (*update_vlapic_mode)(struct vcpu *v);
 
     /*Walk nested p2m  */
     int (*nhvm_hap_walk_L1_p2m)(struct vcpu *v, paddr_t L2_gpa,
@@ -786,6 +787,12 @@ static inline int hvm_pi_update_irte(const struct vcpu *v,
     return alternative_call(hvm_funcs.pi_update_irte, v, pirq, gvec);
 }
 
+static inline void hvm_update_vlapic_mode(struct vcpu *v)
+{
+    if ( hvm_funcs.update_vlapic_mode )
+        alternative_vcall(hvm_funcs.update_vlapic_mode, v);
+}
+
 #else  /* CONFIG_HVM */
 
 #define hvm_enabled false
diff --git a/xen/arch/x86/include/asm/hvm/vmx/vmx.h 
b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
index 234da4a7f4..97d6b810ec 100644
--- a/xen/arch/x86/include/asm/hvm/vmx/vmx.h
+++ b/xen/arch/x86/include/asm/hvm/vmx/vmx.h
@@ -85,7 +85,7 @@ typedef enum {
 void vmx_asm_vmexit_handler(struct cpu_user_regs);
 void vmx_intr_assist(void);
 void noreturn cf_check vmx_do_resume(void);
-void vmx_vlapic_msr_changed(struct vcpu *v);
+void cf_check vmx_vlapic_msr_changed(struct vcpu *v);
 struct hvm_emulate_ctxt;
 void vmx_realmode_emulate_one(struct hvm_emulate_ctxt *hvmemul_ctxt);
 void vmx_realmode(struct cpu_user_regs *regs);
-- 
2.37.2