summaryrefslogtreecommitdiff
path: root/Documentation/virtual
diff options
context:
space:
mode:
authorDavid Hildenbrand <dahi@linux.vnet.ibm.com>2016-06-21 15:19:51 +0300
committerChristian Borntraeger <borntraeger@de.ibm.com>2016-07-18 15:15:00 +0300
commit6502a34cfd6695929086187f63fe670cc3050e68 (patch)
tree774e386aac358c15baeeba02a38bb8b080e3887d /Documentation/virtual
parentaf1bae5497b98cb99d6b0492e6981f060420a00c (diff)
downloadlinux-6502a34cfd6695929086187f63fe670cc3050e68.tar.xz
KVM: s390: allow user space to handle instr 0x0000
We will use illegal instruction 0x0000 for handling 2 byte sw breakpoints from user space. As it can be enabled dynamically via a capability, let's move setting of ICTL_OPEREXC to the post creation step, so we avoid any races when enabling that capability just while adding new cpus. Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com> Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt13
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index c4d2fb0e28de..299306db5d84 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3857,6 +3857,19 @@ as a broadcast even in x2APIC mode in order to support physical x2APIC
without interrupt remapping. This is undesirable in logical mode,
where 0xff represents CPUs 0-7 in cluster 0.
+7.8 KVM_CAP_S390_USER_INSTR0
+
+Architectures: s390
+Parameters: none
+
+With this capability enabled, all illegal instructions 0x0000 (2 bytes) will
+be intercepted and forwarded to user space. User space can use this
+mechanism e.g. to realize 2-byte software breakpoints. The kernel will
+not inject an operating exception for these instructions, user space has
+to take care of that.
+
+This capability can be enabled dynamically even if VCPUs were already
+created and are running.
8. Other capabilities.
----------------------