KVM: PPC: Add support for ePAPR idle hcall in host kernel

And add a new flag definition in kvm_ppc_pvinfo to indicate
whether the host supports the EV_IDLE hcall.
Signed-off-by: Liu Yu <yu.liu@freescale.com>
[stuart.yoder@freescale.com: cleanup,fixes for conditions allowing idle]
Signed-off-by: Stuart Yoder <stuart.yoder@freescale.com>
[agraf: fix typo]
Signed-off-by: Alexander Graf <agraf@suse.de>

Documentation/virtual/kvm/api.txt

@@ -1194,12 +1194,15 @@ struct kvm_ppc_pvinfo {
 This ioctl fetches PV specific information that need to be passed to the guest
 using the device tree or other means from vm context.
 
-For now the only implemented piece of information distributed here is an array
-of 4 instructions that make up a hypercall.
+The hcall array defines 4 instructions that make up a hypercall.
 
 If any additional field gets added to this structure later on, a bit for that
 additional piece of information will be set in the flags bitmap.
 
+The flags bitmap is defined as:
+
+   /* the host supports the ePAPR idle hcall
+   #define KVM_PPC_PVINFO_FLAGS_EV_IDLE   (1<<0)
 
 4.48 KVM_ASSIGN_PCI_DEVICE
 

arch/powerpc/include/asm/Kbuild

@@ -34,5 +34,6 @@ header-y += termios.h
 header-y += types.h
 header-y += ucontext.h
 header-y += unistd.h
+header-y += epapr_hcalls.h
 
 generic-y += rwsem.h

arch/powerpc/kvm/powerpc.c

@@ -38,8 +38,7 @@
 
 int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 {
-	return !(v->arch.shared->msr & MSR_WE) ||
-	       !!(v->arch.pending_exceptions) ||
+	return !!(v->arch.pending_exceptions) ||
 	       v->requests;
 }
 
@@ -86,6 +85,11 @@ int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
 
 		/* Second return value is in r4 */
 		break;
+	case EV_HCALL_TOKEN(EV_IDLE):
+		r = EV_SUCCESS;
+		kvm_vcpu_block(vcpu);
+		clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
+		break;
 	default:
 		r = EV_UNIMPLEMENTED;
 		break;
@@ -779,6 +783,8 @@ static int kvm_vm_ioctl_get_pvinfo(struct kvm_ppc_pvinfo *pvinfo)
 	pvinfo->hcall[3] = inst_nop;
 #endif
 
+	pvinfo->flags = KVM_PPC_PVINFO_FLAGS_EV_IDLE;
+
 	return 0;
 }
 

include/linux/kvm.h

@@ -477,6 +477,8 @@ struct kvm_ppc_smmu_info {
 	struct kvm_ppc_one_seg_page_size sps[KVM_PPC_PAGE_SIZES_MAX_SZ];
 };
 
+#define KVM_PPC_PVINFO_FLAGS_EV_IDLE   (1<<0)
+
 #define KVMIO 0xAE
 
 /* machine type bits, to be used as argument to KVM_CREATE_VM */