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authorAlex Bennée <alex.bennee@linaro.org>2014-09-09 17:27:18 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2014-09-10 11:33:12 +0200
commit4bd9d3441edadff4c8df9de4b5d5386c36667ca6 (patch)
tree82d1d887f23b9136d96688b1eb2a40f19424ce0f /Documentation/virtual
parentf2a25160887e00434ce1361007009120e1fecbda (diff)
KVM: document KVM_SET_GUEST_DEBUG api
In preparation for working on the ARM implementation I noticed the debug interface was missing from the API document. I've pieced together the expected behaviour from the code and commit messages written it up as best I can. Signed-off-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual')
-rw-r--r--Documentation/virtual/kvm/api.txt44
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 6485750ae08a..539c010eade0 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2565,6 +2565,50 @@ associated with the service will be forgotten, and subsequent RTAS
calls by the guest for that service will be passed to userspace to be
handled.
+4.87 KVM_SET_GUEST_DEBUG
+
+Capability: KVM_CAP_SET_GUEST_DEBUG
+Architectures: x86, s390, ppc
+Type: vcpu ioctl
+Parameters: struct kvm_guest_debug (in)
+Returns: 0 on success; -1 on error
+
+struct kvm_guest_debug {
+ __u32 control;
+ __u32 pad;
+ struct kvm_guest_debug_arch arch;
+};
+
+Set up the processor specific debug registers and configure vcpu for
+handling guest debug events. There are two parts to the structure, the
+first a control bitfield indicates the type of debug events to handle
+when running. Common control bits are:
+
+ - KVM_GUESTDBG_ENABLE: guest debugging is enabled
+ - KVM_GUESTDBG_SINGLESTEP: the next run should single-step
+
+The top 16 bits of the control field are architecture specific control
+flags which can include the following:
+
+ - KVM_GUESTDBG_USE_SW_BP: using software breakpoints [x86]
+ - KVM_GUESTDBG_USE_HW_BP: using hardware breakpoints [x86, s390]
+ - KVM_GUESTDBG_INJECT_DB: inject DB type exception [x86]
+ - KVM_GUESTDBG_INJECT_BP: inject BP type exception [x86]
+ - KVM_GUESTDBG_EXIT_PENDING: trigger an immediate guest exit [s390]
+
+For example KVM_GUESTDBG_USE_SW_BP indicates that software breakpoints
+are enabled in memory so we need to ensure breakpoint exceptions are
+correctly trapped and the KVM run loop exits at the breakpoint and not
+running off into the normal guest vector. For KVM_GUESTDBG_USE_HW_BP
+we need to ensure the guest vCPUs architecture specific registers are
+updated to the correct (supplied) values.
+
+The second part of the structure is architecture specific and
+typically contains a set of debug registers.
+
+When debug events exit the main run loop with the reason
+KVM_EXIT_DEBUG with the kvm_debug_exit_arch part of the kvm_run
+structure containing architecture specific debug information.
5. The kvm_run structure
------------------------