[PATCH v7 1/4] KVM: X86: Add vCPU running/preempted state

Wanpeng Li
2017-11-30T06:01:23Z

From: Wanpeng Li <wanpeng.li@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 <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wanpeng Li <wanpeng.li@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 09cc064..763b692 100644
--- a/arch/x86/include/uapi/asm/kvm_para.h
+++ b/arch/x86/include/uapi/asm/kvm_para.h
@@ -51,6 +51,9 @@ 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 b40ffbf..6610b92 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -643,7 +643,7 @@ __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 990df39..bc501aa 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2130,7 +2130,7 @@ 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 */
@@ -2907,7 +2907,7 @@ 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