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Date: Tue, 9 Sep 2014 17:27:18 +0100
From: Alex Bennée <alex.bennee@...aro.org>
To: kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu,
linux-arm-kernel@...ts.infradead.org
Cc: peter.maydell@...aro.org, christoffer.dall@...aro.org,
jan.kiszka@...mens.com, dahi@...ux.vnet.ibm.com,
r65777@...escale.com, marc.zyngier@....com, bp@...e.de,
pbonzini@...hat.com,
Alex Bennée <alex.bennee@...aro.org>,
Gleb Natapov <gleb@...nel.org>,
Randy Dunlap <rdunlap@...radead.org>,
linux-doc@...r.kernel.org (open list:DOCUMENTATION),
linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 1/2] 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@...aro.org>
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index d3dde61..723d3f3 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2575,6 +2575,50 @@ 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
------------------------
--
2.1.0
--
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