[Qemu-devel] [PATCH v5 1/4] cpus: Define callback for QEMU "nmi" command

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This introduces an NMI (Non Maskable Interrupt) nmi_monitor_handler()
callback to the CPU class. It is called from QMP's "nmi" command and
performs an action required to cause debug crash dump on in-kernel
debugger invocation. The callback returns Error**.

This adds support for it in qmp_inject_nmi(). Since no architecture
supports it at the moment, there is no change in behaviour.

This changes inject-nmi command description for HMP and QMP.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v5:
* s/given guest's (CPU|VCPU)/default CPU/
* nmi_monitor_handler() now returns Error**


v4:
* s/\<nmi\>/nmi_monitor_handler/

v3:
* actual nmi() enablement moved from last patch to first patch
* changed description for QMP command too
---
 cpus.c            | 9 ++++++++-
 hmp-commands.hx   | 6 ++----
 include/qom/cpu.h | 1 +
 qapi-schema.json  | 4 ++--
 qmp-commands.hx   | 3 +--
 5 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/cpus.c b/cpus.c
index dd7ac13..b9d6602 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1495,6 +1495,13 @@ void qmp_inject_nmi(Error **errp)
         }
     }
 #else
-    error_set(errp, QERR_UNSUPPORTED);
+    CPUState *cs = qemu_get_cpu(monitor_get_cpu_index());
+    CPUClass *cc = CPU_GET_CLASS(cs);
+
+    if (cs && cc->nmi_monitor_handler) {
+        cc->nmi_monitor_handler(cs, errp);
+    } else {
+        error_set(errp, QERR_UNSUPPORTED);
+    }
 #endif
 }
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 2e462c0..0f26c20 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -830,19 +830,17 @@ The values that can be specified here depend on the machine type, but are
 the same that can be specified in the @code{-boot} command line option.
 ETEXI
 
-#if defined(TARGET_I386) || defined(TARGET_S390X)
     {
         .name       = "nmi",
         .args_type  = "",
         .params     = "",
-        .help       = "inject an NMI on all guest's CPUs",
+        .help       = "inject an NMI on the default CPU",
         .mhandler.cmd = hmp_inject_nmi,
     },
-#endif
 STEXI
 @item nmi @var{cpu}
 @findex nmi
-Inject an NMI (x86) or RESTART (s390x) on the given CPU.
+Inject an NMI on the default CPU.
 
 ETEXI
 
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 4b352a2..f8bd1d5 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -110,6 +110,7 @@ typedef struct CPUClass {
     void (*parse_features)(CPUState *cpu, char *str, Error **errp);
 
     void (*reset)(CPUState *cpu);
+    void (*nmi_monitor_handler)(CPUState *cs, Error **errp);
     int reset_dump_flags;
     bool (*has_work)(CPUState *cpu);
     void (*do_interrupt)(CPUState *cpu);
diff --git a/qapi-schema.json b/qapi-schema.json
index 14b498b..5c03d87 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -1116,13 +1116,13 @@
 ##
 # @inject-nmi:
 #
-# Injects an Non-Maskable Interrupt into all guest's VCPUs.
+# Injects an Non-Maskable Interrupt into the default CPU.
 #
 # Returns:  If successful, nothing
 #
 # Since:  0.14.0
 #
-# Notes: Only x86 Virtual Machines support this command.
+# Note: prior to 2.1, this command was only supported for x86 and s390 VMs
 ##
 { 'command': 'inject-nmi' }
 
diff --git a/qmp-commands.hx b/qmp-commands.hx
index d8aa4ed..b16a0c9 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -477,7 +477,7 @@ SQMP
 inject-nmi
 ----------
 
-Inject an NMI on guest's CPUs.
+Inject an NMI on the default CPU.
 
 Arguments: None.
 
@@ -487,7 +487,6 @@ Example:
 <- { "return": {} }
 
 Note: inject-nmi fails when the guest doesn't support injecting.
-      Currently, only x86 (NMI) and s390x (RESTART) guests do.
 
 EQMP
 
-- 
2.0.0