[PATCH 07/18] kvm: Add MCE signal support for !CONFIG_IOTHREAD

[Jan Kiszka <jan.kiszka@web.de>]

From: Jan Kiszka <jan.kiszka@siemens.com>

Currently, we only configure and process MCE-related SIGBUS events if
CONFIG_IOTHREAD is enabled. Fix this by factoring out the required
handler registration and system configuration. Make sure that events
happening over a VCPU context in non-threaded mode get dispatched as
VCPU MCEs.

We also need to call qemu_kvm_eat_signals in non-threaded mode now, so
move it (unmodified) and add the required Windows stub.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
CC: Huang Ying <ying.huang@intel.com>
---
 cpus.c |  200 +++++++++++++++++++++++++++++++++++++++------------------------
 1 files changed, 124 insertions(+), 76 deletions(-)

diff --git a/cpus.c b/cpus.c
index 6da0f8f..b6f1cfb 100644
--- a/cpus.c
+++ b/cpus.c
@@ -34,9 +34,6 @@
 
 #include "cpus.h"
 #include "compatfd.h"
-#ifdef CONFIG_LINUX
-#include <sys/prctl.h>
-#endif
 
 #ifdef SIGRTMIN
 #define SIG_IPI (SIGRTMIN+4)
@@ -44,10 +41,24 @@
 #define SIG_IPI SIGUSR1
 #endif
 
+#ifdef CONFIG_LINUX
+
+#include <sys/prctl.h>
+
 #ifndef PR_MCE_KILL
 #define PR_MCE_KILL 33
 #endif
 
+#ifndef PR_MCE_KILL_SET
+#define PR_MCE_KILL_SET 1
+#endif
+
+#ifndef PR_MCE_KILL_EARLY
+#define PR_MCE_KILL_EARLY 1
+#endif
+
+#endif /* CONFIG_LINUX */
+
 static CPUState *next_cpu;
 
 /***********************************************************/
@@ -158,6 +169,62 @@ static void cpu_debug_handler(CPUState *env)
     vm_stop(EXCP_DEBUG);
 }
 
+#ifdef CONFIG_LINUX
+static void sigbus_reraise(void)
+{
+    sigset_t set;
+    struct sigaction action;
+
+    memset(&action, 0, sizeof(action));
+    action.sa_handler = SIG_DFL;
+    if (!sigaction(SIGBUS, &action, NULL)) {
+        raise(SIGBUS);
+        sigemptyset(&set);
+        sigaddset(&set, SIGBUS);
+        sigprocmask(SIG_UNBLOCK, &set, NULL);
+    }
+    perror("Failed to re-raise SIGBUS!\n");
+    abort();
+}
+
+static void sigbus_handler(int n, struct qemu_signalfd_siginfo *siginfo,
+                           void *ctx)
+{
+#ifndef CONFIG_IOTHREAD
+    if (cpu_single_env) {
+        if (kvm_on_sigbus_vcpu(cpu_single_env, siginfo->ssi_code,
+                               (void *)(intptr_t)siginfo->ssi_addr)) {
+            sigbus_reraise();
+        }
+        return;
+    }
+#endif
+
+    if (kvm_on_sigbus(siginfo->ssi_code,
+                      (void *)(intptr_t)siginfo->ssi_addr)) {
+        sigbus_reraise();
+    }
+}
+
+static void qemu_init_sigbus(void)
+{
+    struct sigaction action;
+
+    memset(&action, 0, sizeof(action));
+    action.sa_flags = SA_SIGINFO;
+    action.sa_sigaction = (void (*)(int, siginfo_t*, void*))sigbus_handler;
+    sigaction(SIGBUS, &action, NULL);
+
+    prctl(PR_MCE_KILL, PR_MCE_KILL_SET, PR_MCE_KILL_EARLY, 0, 0);
+}
+
+#else /* !CONFIG_LINUX */
+
+static void qemu_init_sigbus(void)
+{
+}
+#endif /* !CONFIG_LINUX */
+
 #ifndef _WIN32
 static int io_thread_fd = -1;
 
@@ -254,6 +321,43 @@ static void qemu_kvm_init_cpu_signals(CPUState *env)
     }
 }
 
+static void qemu_kvm_eat_signals(CPUState *env)
+{
+    struct timespec ts = { 0, 0 };
+    siginfo_t siginfo;
+    sigset_t waitset;
+    sigset_t chkset;
+    int r;
+
+    sigemptyset(&waitset);
+    sigaddset(&waitset, SIG_IPI);
+    sigaddset(&waitset, SIGBUS);
+
+    do {
+        r = sigtimedwait(&waitset, &siginfo, &ts);
+        if (r == -1 && !(errno == EAGAIN || errno == EINTR)) {
+            perror("sigtimedwait");
+            exit(1);
+        }
+
+        switch (r) {
+        case SIGBUS:
+            if (kvm_on_sigbus_vcpu(env, siginfo.si_code, siginfo.si_addr)) {
+                sigbus_reraise();
+            }
+            break;
+        default:
+            break;
+        }
+
+        r = sigpending(&chkset);
+        if (r == -1) {
+            perror("sigpending");
+            exit(1);
+        }
+    } while (sigismember(&chkset, SIG_IPI) || sigismember(&chkset, SIGBUS));
+}
+
 #else /* _WIN32 */
 
 HANDLE qemu_event_handle;
@@ -285,6 +389,10 @@ static void qemu_event_increment(void)
 static void qemu_kvm_init_cpu_signals(CPUState *env)
 {
 }
+
+static void qemu_kvm_eat_signals(CPUState *env)
+{
+}
 #endif /* _WIN32 */
 
 #ifndef CONFIG_IOTHREAD
@@ -292,6 +400,8 @@ int qemu_init_main_loop(void)
 {
     cpu_set_debug_excp_handler(cpu_debug_handler);
 
+    qemu_init_sigbus();
+
     return qemu_event_init();
 }
 
@@ -432,13 +542,9 @@ static void qemu_tcg_init_cpu_signals(void)
     pthread_sigmask(SIG_UNBLOCK, &set, NULL);
 }
 
-static void sigbus_handler(int n, struct qemu_signalfd_siginfo *siginfo,
-                           void *ctx);
-
 static sigset_t block_io_signals(void)
 {
     sigset_t set;
-    struct sigaction action;
 
     /* SIGUSR2 used by posix-aio-compat.c */
     sigemptyset(&set);
@@ -449,15 +555,11 @@ static sigset_t block_io_signals(void)
     sigaddset(&set, SIGIO);
     sigaddset(&set, SIGALRM);
     sigaddset(&set, SIG_IPI);
+#ifdef CONFIG_LINUX
     sigaddset(&set, SIGBUS);
+#endif
     pthread_sigmask(SIG_BLOCK, &set, NULL);
 
-    memset(&action, 0, sizeof(action));
-    action.sa_flags = SA_SIGINFO;
-    action.sa_sigaction = (void (*)(int, siginfo_t*, void*))sigbus_handler;
-    sigaction(SIGBUS, &action, NULL);
-    prctl(PR_MCE_KILL, 1, 1, 0, 0);
-
     return set;
 }
 
@@ -486,6 +588,8 @@ int qemu_init_main_loop(void)
 
     cpu_set_debug_excp_handler(cpu_debug_handler);
 
+    qemu_init_sigbus();
+
     blocked_signals = block_io_signals();
 
     ret = qemu_signalfd_init(blocked_signals);
@@ -592,68 +696,6 @@ static void qemu_tcg_wait_io_event(void)
     }
 }
 
-static void sigbus_reraise(void)
-{
-    sigset_t set;
-    struct sigaction action;
-
-    memset(&action, 0, sizeof(action));
-    action.sa_handler = SIG_DFL;
-    if (!sigaction(SIGBUS, &action, NULL)) {
-        raise(SIGBUS);
-        sigemptyset(&set);
-        sigaddset(&set, SIGBUS);
-        sigprocmask(SIG_UNBLOCK, &set, NULL);
-    }
-    perror("Failed to re-raise SIGBUS!\n");
-    abort();
-}
-
-static void sigbus_handler(int n, struct qemu_signalfd_siginfo *siginfo,
-                           void *ctx)
-{
-    if (kvm_on_sigbus(siginfo->ssi_code, (void *)(intptr_t)siginfo->ssi_addr)) {
-        sigbus_reraise();
-    }
-}
-
-static void qemu_kvm_eat_signals(CPUState *env)
-{
-    struct timespec ts = { 0, 0 };
-    siginfo_t siginfo;
-    sigset_t waitset;
-    sigset_t chkset;
-    int r;
-
-    sigemptyset(&waitset);
-    sigaddset(&waitset, SIG_IPI);
-    sigaddset(&waitset, SIGBUS);
-
-    do {
-        r = sigtimedwait(&waitset, &siginfo, &ts);
-        if (r == -1 && !(errno == EAGAIN || errno == EINTR)) {
-            perror("sigtimedwait");
-            exit(1);
-        }
-
-        switch (r) {
-        case SIGBUS:
-            if (kvm_on_sigbus_vcpu(env, siginfo.si_code, siginfo.si_addr)) {
-                sigbus_reraise();
-            }
-            break;
-        default:
-            break;
-        }
-
-        r = sigpending(&chkset);
-        if (r == -1) {
-            perror("sigpending");
-            exit(1);
-        }
-    } while (sigismember(&chkset, SIG_IPI) || sigismember(&chkset, SIGBUS));
-}
-
 static void qemu_kvm_wait_io_event(CPUState *env)
 {
     while (!cpu_has_work(env))
@@ -912,6 +954,8 @@ static int qemu_cpu_exec(CPUState *env)
 
 bool cpu_exec_all(void)
 {
+    int r;
+
     if (next_cpu == NULL)
         next_cpu = first_cpu;
     for (; next_cpu != NULL && !exit_request; next_cpu = next_cpu->next_cpu) {
@@ -923,7 +967,11 @@ bool cpu_exec_all(void)
         if (qemu_alarm_pending())
             break;
         if (cpu_can_run(env)) {
-            if (qemu_cpu_exec(env) == EXCP_DEBUG) {
+            r = qemu_cpu_exec(env);
+            if (kvm_enabled()) {
+                qemu_kvm_eat_signals(env);
+            }
+            if (r == EXCP_DEBUG) {
                 break;
             }
         } else if (env->stop) {
-- 
1.7.1