[PATCH RFC 14/39] KVM: x86/xen: handle PV IPI vcpu yield

[Joao Martins]

Cooperative Linux guests after an IPI-many may yield vcpu if
any of the IPI'd vcpus were preempted (i.e. runstate is 'runnable'.)
Support SCHEDOP_yield for handling yield.

Signed-off-by: Joao Martins <joao.m.mart...@oracle.com>
---
 arch/x86/kvm/xen.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index ec40cb1de6b6..753a6d2c11cd 100644
--- a/arch/x86/kvm/xen.c
+++ b/arch/x86/kvm/xen.c
@@ -17,6 +17,7 @@
 #include <xen/interface/xen.h>
 #include <xen/interface/vcpu.h>
 #include <xen/interface/event_channel.h>
+#include <xen/interface/sched.h>
 
 #include "trace.h"
 
@@ -668,6 +669,31 @@ static int kvm_xen_hcall_set_timer_op(struct kvm_vcpu 
*vcpu, uint64_t timeout)
        return 0;
 }
 
+static int kvm_xen_hcall_sched_op(struct kvm_vcpu *vcpu, int cmd, u64 param)
+{
+       int ret = -ENOSYS;
+       gpa_t gpa;
+       int idx;
+
+       idx = srcu_read_lock(&vcpu->kvm->srcu);
+       gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL);
+       srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+       if (!gpa)
+               return -EFAULT;
+
+       switch (cmd) {
+       case SCHEDOP_yield:
+               kvm_vcpu_on_spin(vcpu, true);
+               ret = 0;
+               break;
+       default:
+               break;
+       }
+
+       return ret;
+}
+
 int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
 {
        bool longmode;
@@ -714,6 +740,11 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu)
                if (!r)
                        goto hcall_success;
                break;
+       case __HYPERVISOR_sched_op:
+               r = kvm_xen_hcall_sched_op(vcpu, params[0], params[1]);
+               if (!r)
+                       goto hcall_success;
+               break;
        /* fallthrough */
        default:
                break;
-- 
2.11.0