[PATCH 4/6] kvm/i386: Avoid multiple calls to check_extension(KVM_CAP_HYPERV)

[Siddharth Chandrasekaran <sidcha@amazon.de>]

KVM_CAP_HYPERV is a VM ioctl and can be cached at kvm_arch_init()
instead of performing an ioctl each time in hyperv_enabled() which is
called foreach vCPU. Apart from that, this variable will come in handy
in a subsequent patch.

Signed-off-by: Siddharth Chandrasekaran <sidcha@amazon.de>
---
 target/i386/kvm/kvm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index d19a2913fd..362f04ab3f 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -93,6 +93,7 @@ static bool has_msr_misc_enable;
 static bool has_msr_smbase;
 static bool has_msr_bndcfgs;
 static int lm_capable_kernel;
+static bool has_hyperv;
 static bool has_msr_hv_hypercall;
 static bool has_msr_hv_crash;
 static bool has_msr_hv_reset;
@@ -715,8 +716,7 @@ unsigned long kvm_arch_vcpu_id(CPUState *cs)
 
 static bool hyperv_enabled(X86CPU *cpu)
 {
-    CPUState *cs = CPU(cpu);
-    return kvm_check_extension(cs->kvm_state, KVM_CAP_HYPERV) > 0 &&
+    return has_hyperv &&
         ((cpu->hyperv_spinlock_attempts != HYPERV_SPINLOCK_NEVER_NOTIFY) ||
          cpu->hyperv_features || cpu->hyperv_passthrough);
 }
@@ -2172,6 +2172,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
     has_xsave = kvm_check_extension(s, KVM_CAP_XSAVE);
     has_xcrs = kvm_check_extension(s, KVM_CAP_XCRS);
     has_pit_state2 = kvm_check_extension(s, KVM_CAP_PIT_STATE2);
+    has_hyperv = kvm_check_extension(s, KVM_CAP_HYPERV);
 
     hv_vpindex_settable = kvm_check_extension(s, KVM_CAP_HYPERV_VP_INDEX);
 
-- 
2.17.1




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