Make use of cookies for the virtio ccw notification hypercall to speed up
lookup of devices on the io bus.
Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
---
arch/s390/kvm/diag.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/s390/kvm/diag.c b/arch/s390/kvm/diag.c
index 3074475..2a467bf 100644
--- a/arch/s390/kvm/diag.c
+++ b/arch/s390/kvm/diag.c
@@ -108,22 +108,33 @@ static int __diag_ipl_functions(struct kvm_vcpu *vcpu)
static int __diag_virtio_hypercall(struct kvm_vcpu *vcpu)
{
int ret, idx;
+ long cookie;
/* No virtio-ccw notification? Get out quickly. */
if (!vcpu->kvm->arch.css_support ||
(vcpu->run->s.regs.gprs[1] != KVM_S390_VIRTIO_CCW_NOTIFY))
return -EOPNOTSUPP;
+ cookie = vcpu->run->s.regs.gprs[4];
idx = srcu_read_lock(&vcpu->kvm->srcu);
/*
* The layout is as follows:
* - gpr 2 contains the subchannel id (passed as addr)
* - gpr 3 contains the virtqueue index (passed as datamatch)
+ * - gpr 4 contains the index on the bus (optionally)
*/
- ret = kvm_io_bus_write(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
- vcpu->run->s.regs.gprs[2],
- 8, &vcpu->run->s.regs.gprs[3]);
+ ret = kvm_io_bus_write_cookie(vcpu->kvm, KVM_VIRTIO_CCW_NOTIFY_BUS,
+ vcpu->run->s.regs.gprs[2],
+ 8, &vcpu->run->s.regs.gprs[3],
+ &cookie);
srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+ /*
+ * Return cookie in gpr 2, but don't overwrite the register if the
+ * diagnose will be handled by userspace.
+ */
+ if (ret != -EOPNOTSUPP)
+ vcpu->run->s.regs.gprs[2] = cookie;
/* kvm_io_bus_write returns -EOPNOTSUPP if it found no match. */
return ret < 0 ? ret : 0;
}
--
1.8.2.2
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