[Xen-devel] [PATCH RFC V4 2/5] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks

[Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>]

Add a hypercall to KVM hypervisor to support pv-ticketlocks 

KVM_HC_KICK_CPU allows the calling vcpu to kick another vcpu out of halt state.
    
The presence of these hypercalls is indicated to guest via
KVM_FEATURE_PVLOCK_KICK/KVM_CAP_PVLOCK_KICK.

Qemu needs a corresponding patch to pass up the presence of this feature to 
guest via cpuid. Patch to qemu will be sent separately.

Signed-off-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Suzuki Poulose <suzuki@xxxxxxxxxx>
Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>
---
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 734c376..7a94987 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -16,12 +16,14 @@
 #define KVM_FEATURE_CLOCKSOURCE                0
 #define KVM_FEATURE_NOP_IO_DELAY       1
 #define KVM_FEATURE_MMU_OP             2
+
 /* This indicates that the new set of kvmclock msrs
  * are available. The use of 0x11 and 0x12 is deprecated
  */
 #define KVM_FEATURE_CLOCKSOURCE2        3
 #define KVM_FEATURE_ASYNC_PF           4
 #define KVM_FEATURE_STEAL_TIME         5
+#define KVM_FEATURE_PVLOCK_KICK                6
 
 /* The last 8 bits are used to indicate how to interpret the flags field
  * in pvclock structure. If no bits are set, all flags are ignored.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4c938da..c7b05fc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2099,6 +2099,7 @@ int kvm_dev_ioctl_check_extension(long ext)
        case KVM_CAP_XSAVE:
        case KVM_CAP_ASYNC_PF:
        case KVM_CAP_GET_TSC_KHZ:
+       case KVM_CAP_PVLOCK_KICK:
                r = 1;
                break;
        case KVM_CAP_COALESCED_MMIO:
@@ -2576,7 +2577,8 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, 
u32 function,
                             (1 << KVM_FEATURE_NOP_IO_DELAY) |
                             (1 << KVM_FEATURE_CLOCKSOURCE2) |
                             (1 << KVM_FEATURE_ASYNC_PF) |
-                            (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT);
+                            (1 << KVM_FEATURE_CLOCKSOURCE_STABLE_BIT) |
+                            (1 << KVM_FEATURE_PVLOCK_KICK);
 
                if (sched_info_on())
                        entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);
@@ -5304,6 +5306,29 @@ int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
        return 1;
 }
 
+/*
+ * kvm_pv_kick_cpu_op:  Kick a vcpu.
+ *
+ * @apicid - apicid of vcpu to be kicked.
+ */
+static void kvm_pv_kick_cpu_op(struct kvm *kvm, int apicid)
+{
+       struct kvm_vcpu *vcpu = NULL;
+       int i;
+
+       kvm_for_each_vcpu(i, vcpu, kvm) {
+               if (!kvm_apic_present(vcpu))
+                       continue;
+
+               if (kvm_apic_match_dest(vcpu, 0, 0, apicid, 0))
+                       break;
+       }
+       if (vcpu) {
+               kvm_make_request(KVM_REQ_PVLOCK_KICK, vcpu);
+               kvm_vcpu_kick(vcpu);
+       }
+}
+
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 {
        unsigned long nr, a0, a1, a2, a3, ret;
@@ -5340,6 +5365,10 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
        case KVM_HC_MMU_OP:
                r = kvm_pv_mmu_op(vcpu, a0, hc_gpa(vcpu, a1, a2), &ret);
                break;
+       case KVM_HC_KICK_CPU:
+               kvm_pv_kick_cpu_op(vcpu->kvm, a0);
+               ret = 0;
+               break;
        default:
                ret = -KVM_ENOSYS;
                break;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 68e67e5..63fb6b0 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -558,6 +558,7 @@ struct kvm_ppc_pvinfo {
 #define KVM_CAP_PPC_PAPR 68
 #define KVM_CAP_S390_GMAP 71
 #define KVM_CAP_TSC_DEADLINE_TIMER 72
+#define KVM_CAP_PVLOCK_KICK 73
 
 #ifdef KVM_CAP_IRQ_ROUTING
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d526231..3b1ae7b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -50,6 +50,7 @@
 #define KVM_REQ_APF_HALT          12
 #define KVM_REQ_STEAL_UPDATE      13
 #define KVM_REQ_NMI               14
+#define KVM_REQ_PVLOCK_KICK       15
 
 #define KVM_USERSPACE_IRQ_SOURCE_ID    0
 
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 47a070b..19f10bd 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -19,6 +19,7 @@
 #define KVM_HC_MMU_OP                  2
 #define KVM_HC_FEATURES                        3
 #define KVM_HC_PPC_MAP_MAGIC_PAGE      4
+#define KVM_HC_KICK_CPU                        5
 
 /*
  * hypercalls use architecture specific


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel