[Qemu-devel] [PATCH] provide a stub version of kvm-all.c if !CONFIG_KVM

[Paolo Bonzini <pbonzini@redhat.com>]

This allows limited use of kvm functions (which will return ENOSYS)
even in once-compiled modules.  The patch also improves a bit the error
messages for KVM initialization.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
        What about this instead?  I don't like that kvm-stub.c is
        compiled per-target too, but it's basically impossible to
        change this without major changes to the build system.

 Makefile.target |    2 +
 kvm-all.c       |    6 ++-
 kvm-stub.c      |  135 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 kvm.h           |   13 +----
 vl.c            |   16 +++----
 5 files changed, 151 insertions(+), 21 deletions(-)
 create mode 100644 kvm-stub.c

diff --git a/Makefile.target b/Makefile.target
index 167fc8d..c504617 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -1,6 +1,7 @@
 # -*- Mode: makefile -*-
 
 GENERATED_HEADERS = config-target.h
+CONFIG_NO_KVM = $(if $(subst n,,$(CONFIG_KVM)),n,y)
 
 include ../config-host.mak
 include config-devices.mak
@@ -170,6 +171,7 @@ obj-y += vhost_net.o
 obj-$(CONFIG_VHOST_NET) += vhost.o
 obj-y += rwhandler.o
 obj-$(CONFIG_KVM) += kvm.o kvm-all.o
+obj-$(CONFIG_NO_KVM) += kvm-stub.o
 LIBS+=-lz
 
 QEMU_CFLAGS += $(VNC_TLS_CFLAGS)
diff --git a/kvm-all.c b/kvm-all.c
index 7aa5e57..373fd34 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1157,9 +1157,9 @@ int kvm_set_signal_mask(CPUState *env, const sigset_t *sigset)
     return r;
 }
 
-#ifdef KVM_IOEVENTFD
 int kvm_set_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t val, bool assign)
 {
+#ifdef KVM_IOEVENTFD
     struct kvm_ioeventfd kick = {
         .datamatch = val,
         .addr = addr,
@@ -1176,5 +1176,7 @@ int kvm_set_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t val, bool assign)
     if (r < 0)
         return r;
     return 0;
-}
+#else
+    return -ENOSYS;
 #endif
+}
diff --git a/kvm-stub.c b/kvm-stub.c
new file mode 100644
index 0000000..80bb908
--- /dev/null
+++ b/kvm-stub.c
@@ -0,0 +1,135 @@
+/*
+ * QEMU KVM stub
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Author: Paolo Bonzini     <pbonzini@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#include "qemu-common.h"
+#include "sysemu.h"
+#include "hw/hw.h"
+#include "gdbstub.h"
+#include "kvm.h"
+
+int kvm_irqchip_in_kernel(void)
+{
+    return 0;
+}
+
+int kvm_pit_in_kernel(void)
+{
+    return 0;
+}
+
+
+int kvm_init_vcpu(CPUState *env)
+{
+    return -ENOSYS;
+}
+
+int kvm_log_start(target_phys_addr_t phys_addr, ram_addr_t size)
+{
+    return -ENOSYS;
+}
+
+int kvm_log_stop(target_phys_addr_t phys_addr, ram_addr_t size)
+{
+    return -ENOSYS;
+}
+
+int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
+{
+    return -ENOSYS;
+}
+
+int kvm_uncoalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)
+{
+    return -ENOSYS;
+}
+
+int kvm_check_extension(KVMState *s, unsigned int extension)
+{
+    return 0;
+}
+
+int kvm_init(int smp_cpus)
+{
+    return -ENOSYS;
+}
+
+void kvm_flush_coalesced_mmio_buffer(void)
+{
+}
+
+void kvm_cpu_synchronize_state(CPUState *env)
+{
+}
+
+void kvm_cpu_synchronize_post_reset(CPUState *env)
+{
+}
+
+void kvm_cpu_synchronize_post_init(CPUState *env)
+{
+}
+
+int kvm_cpu_exec(CPUState *env)
+{
+    abort ();
+}
+
+int kvm_has_sync_mmu(void)
+{
+    return 0;
+}
+
+int kvm_has_vcpu_events(void)
+{
+    return 0;
+}
+
+int kvm_has_robust_singlestep(void)
+{
+    return 0;
+}
+
+void kvm_setup_guest_memory(void *start, size_t size)
+{
+}
+
+int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)
+{
+    tb_flush(env);
+    return 0;
+}
+
+int kvm_insert_breakpoint(CPUState *current_env, target_ulong addr,
+                          target_ulong len, int type)
+{
+    return -EINVAL;
+}
+
+int kvm_remove_breakpoint(CPUState *current_env, target_ulong addr,
+                          target_ulong len, int type)
+{
+    return -EINVAL;
+}
+
+void kvm_remove_all_breakpoints(CPUState *current_env)
+{
+}
+
+int kvm_set_signal_mask(CPUState *env, const sigset_t *sigset)
+{
+    abort();
+}
+
+int kvm_set_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t val, bool assign)
+{
+    return -ENOSYS;
+}
diff --git a/kvm.h b/kvm.h
index 1e5be27..ea3c97d 100644
--- a/kvm.h
+++ b/kvm.h
@@ -23,8 +23,9 @@
 #include <linux/kvm.h>
 #endif
 
-#ifdef CONFIG_KVM
 extern int kvm_allowed;
+
+#if defined CONFIG_KVM || !defined NEED_CPU_H
 #define kvm_enabled() (kvm_allowed)
 #else
 #define kvm_enabled() (0)
@@ -167,15 +168,7 @@ static inline void cpu_synchronize_post_init(CPUState *env)
     }
 }
 
-#if defined(KVM_IOEVENTFD) && defined(CONFIG_KVM)
-int kvm_set_ioeventfd_pio_word(int fd, uint16_t adr, uint16_t val, bool assign);
-#else
-static inline
-int kvm_set_ioeventfd_pio_word(int fd, uint16_t adr, uint16_t val, bool assign)
-{
-    return -ENOSYS;
-}
 #endif
 
-#endif
+int kvm_set_ioeventfd_pio_word(int fd, uint16_t adr, uint16_t val, bool assign);
 #endif
diff --git a/vl.c b/vl.c
index 6768cf1..9fe4682 100644
--- a/vl.c
+++ b/vl.c
@@ -3235,10 +3235,6 @@ int main(int argc, char **argv, char **envp)
                 do_smbios_option(optarg);
                 break;
             case QEMU_OPTION_enable_kvm:
-                if (!(kvm_available())) {
-                    printf("Option %s not supported for this target\n", popt->name);
-                    exit(1);
-                }
                 kvm_allowed = 1;
                 break;
             case QEMU_OPTION_usb:
@@ -3585,12 +3581,14 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }
 
-    if (kvm_enabled()) {
-        int ret;
-
-        ret = kvm_init(smp_cpus);
+    if (kvm_allowed) {
+        int ret = kvm_init(smp_cpus);
         if (ret < 0) {
-            fprintf(stderr, "failed to initialize KVM\n");
+            if (!kvm_available()) {
+                printf("KVM not supported for this target\n");
+            } else {
+                fprintf(stderr, "failed to initialize KVM: %s\n", strerror(-ret));
+            }
             exit(1);
         }
     }
-- 
1.6.6.1