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authorCornelia Huck <cornelia.huck@de.ibm.com>2012-12-20 15:32:12 +0100
committerMarcelo Tosatti <mtosatti@redhat.com>2013-01-07 19:53:43 -0200
commitfa6b7fe9928d50444c29b29c8563746c6b0c6299 (patch)
tree0be284cf322eb82eefdb3df2743740e5578ba5c4 /Documentation/virtual
parentd6712df95bcfea597fc3ea2405ec13e8b69a7b8c (diff)
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>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt30
1 files changed, 30 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 73bd159c555..f2d6391178b 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2350,6 +2350,22 @@ The possible hypercalls are defined in the Power Architecture Platform
Requirements (PAPR) document available from www.power.org (free
developer registration required to access it).
+ /* KVM_EXIT_S390_TSCH */
+ struct {
+ __u16 subchannel_id;
+ __u16 subchannel_nr;
+ __u32 io_int_parm;
+ __u32 io_int_word;
+ __u32 ipb;
+ __u8 dequeued;
+ } s390_tsch;
+
+s390 specific. This exit occurs when KVM_CAP_S390_CSS_SUPPORT has been enabled
+and TEST SUBCHANNEL was intercepted. If dequeued is set, a pending I/O
+interrupt for the target subchannel has been dequeued and subchannel_id,
+subchannel_nr, io_int_parm and io_int_word contain the parameters for that
+interrupt. ipb is needed for instruction parameter decoding.
+
/* Fix the size of the union. */
char padding[256];
};
@@ -2471,3 +2487,17 @@ For mmu types KVM_MMU_FSL_BOOKE_NOHV and KVM_MMU_FSL_BOOKE_HV:
where "num_sets" is the tlb_sizes[] value divided by the tlb_ways[] value.
- The tsize field of mas1 shall be set to 4K on TLB0, even though the
hardware ignores this value for TLB0.
+
+6.4 KVM_CAP_S390_CSS_SUPPORT
+
+Architectures: s390
+Parameters: none
+Returns: 0 on success; -1 on error
+
+This capability enables support for handling of channel I/O instructions.
+
+TEST PENDING INTERRUPTION and the interrupt portion of TEST SUBCHANNEL are
+handled in-kernel, while the other I/O instructions are passed to userspace.
+
+When this capability is enabled, KVM_EXIT_S390_TSCH will occur on TEST
+SUBCHANNEL intercepts.