[PATCH v2] 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_update_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 v2:
  - rename set_virtual_apic_mode to update_vlapic_mode, suggested by Andrew
  - in hvm_update_vlapic_mode(), call the stub only if available, otherwise
    a BUG() will be triggered every time an svm guest writes the APIC_BASE MSR,
    bug reported by Andrew
  - initialize the stub for vmx unconditionally to maintain current behavior
    since no functional change is intended, bug reported by Andrew (here, I
    decided to place the initialization in start_vmx to be closer to the
    initializations of the other stubs that are relevant to apic virtualization)

 xen/arch/x86/hvm/vlapic.c          | 6 +++---
 xen/arch/x86/hvm/vmx/vmx.c         | 2 ++
 xen/arch/x86/include/asm/hvm/hvm.h | 7 +++++++
 3 files changed, 12 insertions(+), 3 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..dd57aa7623 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -3011,6 +3011,8 @@ const struct hvm_function_table * __init start_vmx(void)
         setup_ept_dump();
     }
 
+    vmx_function_table.update_vlapic_mode = vmx_vlapic_msr_changed;
+
     if ( cpu_has_vmx_virtual_intr_delivery )
     {
         vmx_function_table.update_eoi_exit_bitmap = vmx_update_eoi_exit_bitmap;
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
-- 
2.37.2