[PATCH RESEND 1/3] KVM: Add vCPU running/preempted state

[Wanpeng Li]

From: Wanpeng Li <wanpeng...@hotmail.com>

This patch reuses the preempted field in kvm_steal_time, and will export 
the vcpu running/pre-empted information to the guest from host. This will 
enable guest to intelligently send ipi to running vcpus and set flag for 
pre-empted vcpus. This will prevent waiting for vcpus that are not running.

Cc: Paolo Bonzini <pbonz...@redhat.com>
Cc: Radim Krčmář <rkrc...@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng...@hotmail.com>
---
 arch/x86/include/uapi/asm/kvm_para.h | 3 +++
 arch/x86/kernel/kvm.c                | 2 +-
 arch/x86/kvm/x86.c                   | 4 ++--
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/uapi/asm/kvm_para.h 
b/arch/x86/include/uapi/asm/kvm_para.h
index a965e5b0..ff23ce9 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -50,6 +50,9 @@ struct kvm_steal_time {
        __u32 pad[11];
 };
 
+#define KVM_VCPU_NOT_PREEMPTED      (0 << 0)
+#define KVM_VCPU_PREEMPTED          (1 << 0)
+
 #define KVM_CLOCK_PAIRING_WALLCLOCK 0
 struct kvm_clock_pairing {
        __s64 sec;
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 8bb9594..1b1b641 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -608,7 +608,7 @@ __visible bool __kvm_vcpu_is_preempted(long cpu)
 {
        struct kvm_steal_time *src = &per_cpu(steal_time, cpu);
 
-       return !!src->preempted;
+       return !!(src->preempted & KVM_VCPU_PREEMPTED);
 }
 PV_CALLEE_SAVE_REGS_THUNK(__kvm_vcpu_is_preempted);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d2507c6..1ea28a2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2116,7 +2116,7 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
                &vcpu->arch.st.steal, sizeof(struct kvm_steal_time))))
                return;
 
-       vcpu->arch.st.steal.preempted = 0;
+       vcpu->arch.st.steal.preempted = KVM_VCPU_NOT_PREEMPTED;
 
        if (vcpu->arch.st.steal.version & 1)
                vcpu->arch.st.steal.version += 1;  /* first time write, random 
junk */
@@ -2887,7 +2887,7 @@ static void kvm_steal_time_set_preempted(struct kvm_vcpu 
*vcpu)
        if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
                return;
 
-       vcpu->arch.st.steal.preempted = 1;
+       vcpu->arch.st.steal.preempted = KVM_VCPU_PREEMPTED;
 
        kvm_write_guest_offset_cached(vcpu->kvm, &vcpu->arch.st.stime,
                        &vcpu->arch.st.steal.preempted,
-- 
2.7.4