[Qemu-devel] [PATCH v6 1/4] cpus: Define callback for QEMU "nmi" command

[Alexey Kardashevskiy <aik@ozlabs.ru>]

This introduces an NMI (Non Maskable Interrupt) interface with
a single nmi_monitor_handler() method. A machine or a device can
implement it. This searches for an QOM object which supports the interface
and if it is implemented , calls it. The callback implements 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:
v6:
* NMI is an interface again

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                |  3 +-
 hmp-commands.hx       |  6 ++--
 hw/core/Makefile.objs |  1 +
 hw/core/nmi.c         | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++
 include/hw/nmi.h      | 46 +++++++++++++++++++++++++++++
 qapi-schema.json      |  4 +--
 qmp-commands.hx       |  3 +-
 7 files changed, 135 insertions(+), 9 deletions(-)
 create mode 100644 hw/core/nmi.c
 create mode 100644 include/hw/nmi.h

diff --git a/cpus.c b/cpus.c
index dd7ac13..da1f6a9 100644
--- a/cpus.c
+++ b/cpus.c
@@ -38,6 +38,7 @@
 #include "qemu/main-loop.h"
 #include "qemu/bitmap.h"
 #include "qemu/seqlock.h"
+#include "hw/nmi.h"
 
 #ifndef _WIN32
 #include "qemu/compatfd.h"
@@ -1495,6 +1496,6 @@ void qmp_inject_nmi(Error **errp)
         }
     }
 #else
-    error_set(errp, QERR_UNSUPPORTED);
+    nmi(monitor_get_cpu_index(), errp);
 #endif
 }
diff --git a/hmp-commands.hx b/hmp-commands.hx
index 2e462c0..c25f88f 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",
         .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 (x86/s390) or all CPUs (ppc64).
 
 ETEXI
 
diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
index 5377d05..17845df 100644
--- a/hw/core/Makefile.objs
+++ b/hw/core/Makefile.objs
@@ -4,6 +4,7 @@ common-obj-y += fw-path-provider.o
 # irq.o needed for qdev GPIO handling:
 common-obj-y += irq.o
 common-obj-y += hotplug.o
+common-obj-y += nmi.o
 
 common-obj-$(CONFIG_EMPTY_SLOT) += empty_slot.o
 common-obj-$(CONFIG_XILINX_AXI) += stream.o
diff --git a/hw/core/nmi.c b/hw/core/nmi.c
new file mode 100644
index 0000000..e81ebab
--- /dev/null
+++ b/hw/core/nmi.c
@@ -0,0 +1,81 @@
+/*
+ *  NMI monitor handler class and helpers.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License,
+ *  or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "hw/nmi.h"
+#include "qapi/qmp/qerror.h"
+
+struct do_nmi_s {
+    int cpu_index;
+    Error *errp;
+    bool handled;
+};
+
+static void nmi_children(Object *o, struct do_nmi_s *ns);
+
+static int do_nmi(Object *o, void *opaque)
+{
+    struct do_nmi_s *ns = opaque;
+    NMI *n = (NMI *) object_dynamic_cast(o, TYPE_NMI);
+
+    if (n) {
+        NMIClass *nc = NMI_GET_CLASS(n);
+
+        ns->handled = true;
+        nc->nmi_monitor_handler(n, ns->cpu_index, &ns->errp);
+        if (ns->errp) {
+            return -1;
+        }
+    }
+    nmi_children(o, ns);
+
+    return 0;
+}
+
+void nmi_children(Object *o, struct do_nmi_s *ns)
+{
+    object_child_foreach(o, do_nmi, ns);
+}
+
+void nmi(int cpu_index, Error **errp)
+{
+    Object *root = object_get_root();
+    struct do_nmi_s ns = {
+        .cpu_index = cpu_index,
+        .errp = NULL,
+        .handled = false
+    };
+
+    nmi_children(root, &ns);
+    if (ns.handled) {
+        error_propagate(errp, ns.errp);
+    } else {
+        error_set(errp, QERR_UNSUPPORTED);
+    }
+}
+
+static const TypeInfo nmi_info = {
+    .name          = TYPE_NMI,
+    .parent        = TYPE_INTERFACE,
+    .class_size    = sizeof(NMIClass),
+};
+
+static void nmi_register_types(void)
+{
+    type_register_static(&nmi_info);
+}
+
+type_init(nmi_register_types)
diff --git a/include/hw/nmi.h b/include/hw/nmi.h
new file mode 100644
index 0000000..c2d8206
--- /dev/null
+++ b/include/hw/nmi.h
@@ -0,0 +1,46 @@
+/*
+ *  NMI monitor handler class and helpers definitions.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License,
+ *  or (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef NMI_H
+#define NMI_H 1
+
+#include "qemu-common.h"
+#include "qom/object.h"
+
+#define TYPE_NMI "nmi"
+
+#define NMI_CLASS(klass) \
+     OBJECT_CLASS_CHECK(NMIClass, (klass), TYPE_NMI)
+#define NMI_GET_CLASS(obj) \
+    OBJECT_GET_CLASS(NMIClass, (obj), TYPE_NMI)
+#define NMI(obj) \
+     INTERFACE_CHECK(NMI, (obj), TYPE_NMI)
+
+typedef struct NMI {
+    Object parent_obj;
+} NMI;
+
+typedef struct NMIClass {
+    InterfaceClass parent_class;
+
+    void (*nmi_monitor_handler)(NMI *n, int cpu_index, Error **errp);
+} NMIClass;
+
+void nmi(int cpu_index, Error **errp);
+
+#endif /* NMI_H */
+
diff --git a/qapi-schema.json b/qapi-schema.json
index 14b498b..8bf9849 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 (x86/s390) or all CPUs (ppc64).
 #
 # 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..0028d96 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 (x86/s390) or all CPUs (ppc64).
 
 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