[RFC PATCH v2 22/22] i386/xen: implement HYPERVISOR_sched_op

[David Woodhouse]

From: Joao Martins <joao.m.martins@oracle.com>

It allows to shutdown itself via hypercall with any of the 3 reasons:
  1) self-reboot
  2) shutdown
  3) crash

Implementing SCHEDOP_shutdown sub op let us handle crashes gracefully rather
than leading to triple faults if it remains unimplemented.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 target/i386/xen.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/target/i386/xen.c b/target/i386/xen.c
index f102c40f04..5f3b91450d 100644
--- a/target/i386/xen.c
+++ b/target/i386/xen.c
@@ -17,6 +17,7 @@
 #include "trace.h"
 #include "hw/i386/kvm/xen_overlay.h"
 #include "hw/i386/kvm/xen_evtchn.h"
+#include "sysemu/runstate.h"
 
 #define __XEN_INTERFACE_VERSION__ 0x00040400
 
@@ -25,6 +26,7 @@
 #include "standard-headers/xen/hvm/hvm_op.h"
 #include "standard-headers/xen/hvm/params.h"
 #include "standard-headers/xen/vcpu.h"
+#include "standard-headers/xen/sched.h"
 #include "standard-headers/xen/event_channel.h"
 
 static bool kvm_gva_to_gpa(CPUState *cs, uint64_t gva, uint64_t *gpa,
@@ -491,6 +493,45 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit 
*exit,
     return true;
 }
 
+static int schedop_shutdown(CPUState *cs, uint64_t arg)
+{
+    struct sched_shutdown shutdown;
+
+    if (kvm_copy_from_gva(cs, arg, &shutdown, sizeof(shutdown))) {
+        return -EFAULT;
+    }
+
+    if (shutdown.reason == SHUTDOWN_crash) {
+        cpu_dump_state(cs, stderr, CPU_DUMP_CODE);
+        qemu_system_guest_panicked(NULL);
+    } else if (shutdown.reason == SHUTDOWN_reboot) {
+        qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+    } else if (shutdown.reason == SHUTDOWN_poweroff) {
+        qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_SHUTDOWN);
+    }
+
+    return 0;
+}
+
+static bool kvm_xen_hcall_sched_op(struct kvm_xen_exit *exit, X86CPU *cpu,
+                                   int cmd, uint64_t arg)
+{
+    CPUState *cs = CPU(cpu);
+    int err = -ENOSYS;
+
+    switch (cmd) {
+    case SCHEDOP_shutdown: {
+          err = schedop_shutdown(cs, arg);
+          break;
+       }
+    default:
+            return false;
+    }
+
+    exit->u.hcall.result = err;
+    return true;
+}
+
 static bool __kvm_xen_handle_exit(X86CPU *cpu, struct kvm_xen_exit *exit)
 {
     uint16_t code = exit->u.hcall.input;
@@ -501,6 +542,10 @@ static bool __kvm_xen_handle_exit(X86CPU *cpu, struct 
kvm_xen_exit *exit)
     }
 
     switch (code) {
+    case __HYPERVISOR_sched_op_compat:
+    case __HYPERVISOR_sched_op:
+        return kvm_xen_hcall_sched_op(exit, cpu, exit->u.hcall.params[0],
+                                      exit->u.hcall.params[1]);
     case __HYPERVISOR_event_channel_op_compat:
         return kvm_xen_hcall_evtchn_op_compat(exit, cpu,
                                               exit->u.hcall.params[0]);
-- 
2.35.3