From: Alex Bennée Date: Tue, 9 Sep 2014 16:27:18 +0000 (+0100) Subject: KVM: document KVM_SET_GUEST_DEBUG api X-Git-Tag: firefly_0821_release~176^2~3129^2~41 X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=4bd9d3441edadff4c8df9de4b5d5386c36667ca6;p=firefly-linux-kernel-4.4.55.git 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 Signed-off-by: Paolo Bonzini --- 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 ------------------------