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authorKonstantin Weitz <WEITZKON@de.ibm.com>2012-04-25 15:30:38 +0200
committerMarcelo Tosatti <mtosatti@redhat.com>2012-04-30 21:38:31 -0300
commit41628d334361670d825fb03c04568f5ef9f084dc (patch)
tree88b2eadd0f7de12f1d8b226e4491532b8783ee94 /arch/s390/kvm/diag.c
parentb6ddf05ff68d81a7c1736717faf492b70e9bf4f9 (diff)
downloadlinux-linaro-stable-41628d334361670d825fb03c04568f5ef9f084dc.tar.gz
KVM: s390: Implement the directed yield (diag 9c) hypervisor call for KVM
This patch implements the directed yield hypercall found on other System z hypervisors. It delegates execution time to the virtual cpu specified in the instruction's parameter. Useful to avoid long spinlock waits in the guest. Christian Borntraeger: moved common code in virt/kvm/ Signed-off-by: Konstantin Weitz <WEITZKON@de.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Diffstat (limited to 'arch/s390/kvm/diag.c')
-rw-r--r--arch/s390/kvm/diag.c25
1 files changed, 25 insertions, 0 deletions
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index a353f0ea45c2..2d2ae327b747 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -53,6 +53,29 @@ static int __diag_time_slice_end(struct kvm_vcpu *vcpu)
return 0;
}
+static int __diag_time_slice_end_directed(struct kvm_vcpu *vcpu)
+{
+ struct kvm *kvm = vcpu->kvm;
+ struct kvm_vcpu *tcpu;
+ int tid;
+ int i;
+
+ tid = vcpu->run->s.regs.gprs[(vcpu->arch.sie_block->ipa & 0xf0) >> 4];
+ vcpu->stat.diagnose_9c++;
+ VCPU_EVENT(vcpu, 5, "diag time slice end directed to %d", tid);
+
+ if (tid == vcpu->vcpu_id)
+ return 0;
+
+ kvm_for_each_vcpu(i, tcpu, kvm)
+ if (tcpu->vcpu_id == tid) {
+ kvm_vcpu_yield_to(tcpu);
+ break;
+ }
+
+ return 0;
+}
+
static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
{
unsigned int reg = vcpu->arch.sie_block->ipa & 0xf;
@@ -89,6 +112,8 @@ int kvm_s390_handle_diag(struct kvm_vcpu *vcpu)
return diag_release_pages(vcpu);
case 0x44:
return __diag_time_slice_end(vcpu);
+ case 0x9c:
+ return __diag_time_slice_end_directed(vcpu);
case 0x308:
return __diag_ipl_functions(vcpu);
default: