KVM: s390: Add support for channel I/O instructions.
Add a new capability, KVM_CAP_S390_CSS_SUPPORT, which will pass
intercepts for channel I/O instructions to userspace. Only I/O
instructions interacting with I/O interrupts need to be handled
in-kernel:
- TEST PENDING INTERRUPTION (tpi) dequeues and stores pending
interrupts entirely in-kernel.
- TEST SUBCHANNEL (tsch) dequeues pending interrupts in-kernel
and exits via KVM_EXIT_S390_TSCH to userspace for subchannel-
related processing.
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 8ad776f..0ef9894 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -127,13 +127,96 @@
return 0;
}
+static int handle_tpi(struct kvm_vcpu *vcpu)
+{
+ u64 addr;
+ struct kvm_s390_interrupt_info *inti;
+ int cc;
+
+ addr = kvm_s390_get_base_disp_s(vcpu);
+
+ inti = kvm_s390_get_io_int(vcpu->kvm, vcpu->run->s.regs.crs[6], 0);
+ if (inti) {
+ if (addr) {
+ /*
+ * Store the two-word I/O interruption code into the
+ * provided area.
+ */
+ put_guest_u16(vcpu, addr, inti->io.subchannel_id);
+ put_guest_u16(vcpu, addr + 2, inti->io.subchannel_nr);
+ put_guest_u32(vcpu, addr + 4, inti->io.io_int_parm);
+ } else {
+ /*
+ * Store the three-word I/O interruption code into
+ * the appropriate lowcore area.
+ */
+ put_guest_u16(vcpu, 184, inti->io.subchannel_id);
+ put_guest_u16(vcpu, 186, inti->io.subchannel_nr);
+ put_guest_u32(vcpu, 188, inti->io.io_int_parm);
+ put_guest_u32(vcpu, 192, inti->io.io_int_word);
+ }
+ cc = 1;
+ } else
+ cc = 0;
+ kfree(inti);
+ /* Set condition code and we're done. */
+ vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
+ vcpu->arch.sie_block->gpsw.mask |= (cc & 3ul) << 44;
+ return 0;
+}
+
+static int handle_tsch(struct kvm_vcpu *vcpu)
+{
+ struct kvm_s390_interrupt_info *inti;
+
+ inti = kvm_s390_get_io_int(vcpu->kvm, 0,
+ vcpu->run->s.regs.gprs[1]);
+
+ /*
+ * Prepare exit to userspace.
+ * We indicate whether we dequeued a pending I/O interrupt
+ * so that userspace can re-inject it if the instruction gets
+ * a program check. While this may re-order the pending I/O
+ * interrupts, this is no problem since the priority is kept
+ * intact.
+ */
+ vcpu->run->exit_reason = KVM_EXIT_S390_TSCH;
+ vcpu->run->s390_tsch.dequeued = !!inti;
+ if (inti) {
+ vcpu->run->s390_tsch.subchannel_id = inti->io.subchannel_id;
+ vcpu->run->s390_tsch.subchannel_nr = inti->io.subchannel_nr;
+ vcpu->run->s390_tsch.io_int_parm = inti->io.io_int_parm;
+ vcpu->run->s390_tsch.io_int_word = inti->io.io_int_word;
+ }
+ vcpu->run->s390_tsch.ipb = vcpu->arch.sie_block->ipb;
+ kfree(inti);
+ return -EREMOTE;
+}
+
static int handle_io_inst(struct kvm_vcpu *vcpu)
{
VCPU_EVENT(vcpu, 4, "%s", "I/O instruction");
- /* condition code 3 */
- vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
- vcpu->arch.sie_block->gpsw.mask |= (3 & 3ul) << 44;
- return 0;
+
+ if (vcpu->kvm->arch.css_support) {
+ /*
+ * Most I/O instructions will be handled by userspace.
+ * Exceptions are tpi and the interrupt portion of tsch.
+ */
+ if (vcpu->arch.sie_block->ipa == 0xb236)
+ return handle_tpi(vcpu);
+ if (vcpu->arch.sie_block->ipa == 0xb235)
+ return handle_tsch(vcpu);
+ /* Handle in userspace. */
+ return -EOPNOTSUPP;
+ } else {
+ /*
+ * Set condition code 3 to stop the guest from issueing channel
+ * I/O instructions.
+ */
+ vcpu->arch.sie_block->gpsw.mask &= ~(3ul << 44);
+ vcpu->arch.sie_block->gpsw.mask |= (3 & 3ul) << 44;
+ return 0;
+ }
}
static int handle_stfl(struct kvm_vcpu *vcpu)