[PATCH v4 2/4] x86/vcpu: track hvm vcpu number on the system

[Chao Gao <chao.gao@intel.com>]

This number is used to calculate the average vcpus per pcpu ratio.

Signed-off-by: Chao Gao <chao.gao@intel.com>
---
v4:
 - move the place we increase/decrease the hvm vcpu number to
 hvm_vcpu_{initialise, destory}

---
 xen/arch/x86/hvm/hvm.c        | 6 ++++++
 xen/include/asm-x86/hvm/hvm.h | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 3ed6ec4..6a510b3 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -109,6 +109,9 @@ static const char __initconst warning_hvm_fep[] =
 static bool_t __initdata opt_altp2m_enabled = 0;
 boolean_param("altp2m", opt_altp2m_enabled);
 
+/* Total number of HVM vCPUs on this system */
+atomic_t num_hvm_vcpus;
+
 static int cpu_callback(
     struct notifier_block *nfb, unsigned long action, void *hcpu)
 {
@@ -1512,6 +1515,7 @@ int hvm_vcpu_initialise(struct vcpu *v)
 
     hvm_update_guest_vendor(v);
 
+    atomic_inc(&num_hvm_vcpus);
     return 0;
 
  fail6:
@@ -1530,6 +1534,8 @@ int hvm_vcpu_initialise(struct vcpu *v)
 
 void hvm_vcpu_destroy(struct vcpu *v)
 {
+    atomic_dec(&num_hvm_vcpus);
+
     viridian_vcpu_deinit(v);
 
     hvm_all_ioreq_servers_remove_vcpu(v->domain, v);
diff --git a/xen/include/asm-x86/hvm/hvm.h b/xen/include/asm-x86/hvm/hvm.h
index b687e03..c51bd9f 100644
--- a/xen/include/asm-x86/hvm/hvm.h
+++ b/xen/include/asm-x86/hvm/hvm.h
@@ -25,6 +25,7 @@
 #include <asm/hvm/asid.h>
 #include <public/domctl.h>
 #include <public/hvm/save.h>
+#include <xen/atomic.h>
 #include <xen/mm.h>
 
 #ifdef CONFIG_HVM_FEP
@@ -233,6 +234,8 @@ extern bool_t hvm_enabled;
 extern bool_t cpu_has_lmsl;
 extern s8 hvm_port80_allowed;
 
+extern atomic_t num_hvm_vcpus;
+
 extern const struct hvm_function_table *start_svm(void);
 extern const struct hvm_function_table *start_vmx(void);
 
-- 
1.8.3.1


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