[Qemu-devel] [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Qemu-devel] [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Blue Swirl]

Remove dependency of vl.c to KVM, then we can partially revert
b33612d03540fda7fa67485f1c20395beb7a2bf0.

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
---
 Makefile.objs   |    2 +-
 Makefile.target |    2 +-
 arch_init.c     |   20 ++++++++++++++++++++
 arch_init.h     |    2 ++
 vl.c            |   14 ++------------
 5 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/Makefile.objs b/Makefile.objs
index 74d7a3d..4cc8ea6 100644
--- a/Makefile.objs
+++ b/Makefile.objs
@@ -128,7 +128,7 @@ user-obj-y += cutils.o cache-utils.o
 # libhw

 hw-obj-y =
-hw-obj-y += loader.o
+hw-obj-y += vl.o loader.o
 hw-obj-y += virtio.o virtio-console.o
 hw-obj-y += fw_cfg.o pci.o pci_host.o pcie_host.o
 hw-obj-y += watchdog.o
diff --git a/Makefile.target b/Makefile.target
index 167fc8d..2aa02f5 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -161,7 +161,7 @@ endif #CONFIG_BSD_USER
 # System emulator target
 ifdef CONFIG_SOFTMMU

-obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o vl.o
+obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o
 # virtio has to be here due to weird dependency between PCI and virtio-net.
 # need to fix this properly
 obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o
virtio-serial-bus.o
diff --git a/arch_init.c b/arch_init.c
index cfc03ea..001c560 100644
--- a/arch_init.c
+++ b/arch_init.c
@@ -41,6 +41,8 @@
 #include "gdbstub.h"
 #include "hw/smbios.h"

+int kvm_allowed = 0;
+
 #ifdef TARGET_SPARC
 int graphic_width = 1024;
 int graphic_height = 768;
@@ -508,3 +510,21 @@ int xen_available(void)
     return 0;
 #endif
 }
+
+void enable_kvm(void)
+{
+    kvm_allowed = 1;
+}
+
+void kvm_maybe_init(int smp_cpus)
+{
+    if (kvm_enabled()) {
+        int ret;
+
+        ret = kvm_init(smp_cpus);
+        if (ret < 0) {
+            fprintf(stderr, "failed to initialize KVM\n");
+            exit(1);
+        }
+    }
+}
diff --git a/arch_init.h b/arch_init.h
index 682890c..dde4309 100644
--- a/arch_init.h
+++ b/arch_init.h
@@ -29,5 +29,7 @@ void cpudef_init(void);
 int audio_available(void);
 int kvm_available(void);
 int xen_available(void);
+void enable_kvm(void);
+void kvm_maybe_init(int smp_cpus);

 #endif
diff --git a/vl.c b/vl.c
index 03fccbf..cc214dd 100644
--- a/vl.c
+++ b/vl.c
@@ -145,7 +145,6 @@ int main(int argc, char **argv)
 #include "dma.h"
 #include "audio/audio.h"
 #include "migration.h"
-#include "kvm.h"
 #include "balloon.h"
 #include "qemu-option.h"
 #include "qemu-config.h"
@@ -241,7 +240,6 @@ uint8_t qemu_uuid[16];
 static QEMUBootSetHandler *boot_set_handler;
 static void *boot_set_opaque;

-int kvm_allowed = 0;
 uint32_t xen_domid;
 enum xen_mode xen_mode = XEN_EMULATE;

@@ -3228,7 +3226,7 @@ int main(int argc, char **argv, char **envp)
                     printf("Option %s not supported for this
target\n", popt->name);
                     exit(1);
                 }
-                kvm_allowed = 1;
+                enable_kvm();
                 break;
             case QEMU_OPTION_usb:
                 usb_enabled = 1;
@@ -3574,15 +3572,7 @@ int main(int argc, char **argv, char **envp)
         exit(1);
     }

-    if (kvm_enabled()) {
-        int ret;
-
-        ret = kvm_init(smp_cpus);
-        if (ret < 0) {
-            fprintf(stderr, "failed to initialize KVM\n");
-            exit(1);
-        }
-    }
+    kvm_maybe_init(smp_cpus);

     if (qemu_init_main_loop()) {
         fprintf(stderr, "qemu_init_main_loop failed\n");
-- 
1.6.2.4

Re: [Qemu-devel] [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Anthony Liguori]

On 04/01/2010 03:07 PM, Blue Swirl wrote:
> Remove dependency of vl.c to KVM, then we can partially revert
> b33612d03540fda7fa67485f1c20395beb7a2bf0.
>
> Signed-off-by: Blue Swirl<blauwirbel@gmail.com>
> ---
>   Makefile.objs   |    2 +-
>   Makefile.target |    2 +-
>   arch_init.c     |   20 ++++++++++++++++++++
>   arch_init.h     |    2 ++
>   vl.c            |   14 ++------------
>   5 files changed, 26 insertions(+), 14 deletions(-)
>
> diff --git a/Makefile.objs b/Makefile.objs
> index 74d7a3d..4cc8ea6 100644
> --- a/Makefile.objs
> +++ b/Makefile.objs
> @@ -128,7 +128,7 @@ user-obj-y += cutils.o cache-utils.o
>   # libhw
>
>   hw-obj-y =
> -hw-obj-y += loader.o
> +hw-obj-y += vl.o loader.o
>   hw-obj-y += virtio.o virtio-console.o
>   hw-obj-y += fw_cfg.o pci.o pci_host.o pcie_host.o
>   hw-obj-y += watchdog.o
> diff --git a/Makefile.target b/Makefile.target
> index 167fc8d..2aa02f5 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -161,7 +161,7 @@ endif #CONFIG_BSD_USER
>   # System emulator target
>   ifdef CONFIG_SOFTMMU
>
> -obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o vl.o
> +obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o
>   # virtio has to be here due to weird dependency between PCI and virtio-net.
>   # need to fix this properly
>   obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o
> virtio-serial-bus.o
> diff --git a/arch_init.c b/arch_init.c
> index cfc03ea..001c560 100644
> --- a/arch_init.c
> +++ b/arch_init.c
> @@ -41,6 +41,8 @@
>   #include "gdbstub.h"
>   #include "hw/smbios.h"
>
> +int kvm_allowed = 0;
> +
>   #ifdef TARGET_SPARC
>   int graphic_width = 1024;
>   int graphic_height = 768;
> @@ -508,3 +510,21 @@ int xen_available(void)
>       return 0;
>   #endif
>   }
> +
> +void enable_kvm(void)
> +{
> +    kvm_allowed = 1;
> +}
>    

Can we get away with keeping a local to vl.c use_kvm flag and then call 
kvm_init() if use_kvm in vl.c?

We can stick a stub kvm_init() in arch_init.c if !CONFIG_KVM.

Regards,

Anthony LIguori

> +void kvm_maybe_init(int smp_cpus)
> +{
> +    if (kvm_enabled()) {
> +        int ret;
> +
> +        ret = kvm_init(smp_cpus);
> +        if (ret<  0) {
> +            fprintf(stderr, "failed to initialize KVM\n");
> +            exit(1);
> +        }
> +    }
> +}
> diff --git a/arch_init.h b/arch_init.h
> index 682890c..dde4309 100644
> --- a/arch_init.h
> +++ b/arch_init.h
> @@ -29,5 +29,7 @@ void cpudef_init(void);
>   int audio_available(void);
>   int kvm_available(void);
>   int xen_available(void);
> +void enable_kvm(void);
> +void kvm_maybe_init(int smp_cpus);
>
>   #endif
> diff --git a/vl.c b/vl.c
> index 03fccbf..cc214dd 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -145,7 +145,6 @@ int main(int argc, char **argv)
>   #include "dma.h"
>   #include "audio/audio.h"
>   #include "migration.h"
> -#include "kvm.h"
>   #include "balloon.h"
>   #include "qemu-option.h"
>   #include "qemu-config.h"
> @@ -241,7 +240,6 @@ uint8_t qemu_uuid[16];
>   static QEMUBootSetHandler *boot_set_handler;
>   static void *boot_set_opaque;
>
> -int kvm_allowed = 0;
>   uint32_t xen_domid;
>   enum xen_mode xen_mode = XEN_EMULATE;
>
> @@ -3228,7 +3226,7 @@ int main(int argc, char **argv, char **envp)
>                       printf("Option %s not supported for this
> target\n", popt->name);
>                       exit(1);
>                   }
> -                kvm_allowed = 1;
> +                enable_kvm();
>                   break;
>               case QEMU_OPTION_usb:
>                   usb_enabled = 1;
> @@ -3574,15 +3572,7 @@ int main(int argc, char **argv, char **envp)
>           exit(1);
>       }
>
> -    if (kvm_enabled()) {
> -        int ret;
> -
> -        ret = kvm_init(smp_cpus);
> -        if (ret<  0) {
> -            fprintf(stderr, "failed to initialize KVM\n");
> -            exit(1);
> -        }
> -    }
> +    kvm_maybe_init(smp_cpus);
>
>       if (qemu_init_main_loop()) {
>           fprintf(stderr, "qemu_init_main_loop failed\n");
>    

Re: [Qemu-devel] [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Blue Swirl]

On 4/1/10, Anthony Liguori <anthony@codemonkey.ws> wrote:
> On 04/01/2010 03:07 PM, Blue Swirl wrote:
>
> > Remove dependency of vl.c to KVM, then we can partially revert
> > b33612d03540fda7fa67485f1c20395beb7a2bf0.
> >
> > Signed-off-by: Blue Swirl<blauwirbel@gmail.com>
> > ---
> >  Makefile.objs   |    2 +-
> >  Makefile.target |    2 +-
> >  arch_init.c     |   20 ++++++++++++++++++++
> >  arch_init.h     |    2 ++
> >  vl.c            |   14 ++------------
> >  5 files changed, 26 insertions(+), 14 deletions(-)
> >
> > diff --git a/Makefile.objs b/Makefile.objs
> > index 74d7a3d..4cc8ea6 100644
> > --- a/Makefile.objs
> > +++ b/Makefile.objs
> > @@ -128,7 +128,7 @@ user-obj-y += cutils.o cache-utils.o
> >  # libhw
> >
> >  hw-obj-y =
> > -hw-obj-y += loader.o
> > +hw-obj-y += vl.o loader.o
> >  hw-obj-y += virtio.o virtio-console.o
> >  hw-obj-y += fw_cfg.o pci.o pci_host.o pcie_host.o
> >  hw-obj-y += watchdog.o
> > diff --git a/Makefile.target b/Makefile.target
> > index 167fc8d..2aa02f5 100644
> > --- a/Makefile.target
> > +++ b/Makefile.target
> > @@ -161,7 +161,7 @@ endif #CONFIG_BSD_USER
> >  # System emulator target
> >  ifdef CONFIG_SOFTMMU
> >
> > -obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o vl.o
> > +obj-y = arch_init.o cpus.o monitor.o machine.o gdbstub.o
> >  # virtio has to be here due to weird dependency between PCI and
> virtio-net.
> >  # need to fix this properly
> >  obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o
> > virtio-serial-bus.o
> > diff --git a/arch_init.c b/arch_init.c
> > index cfc03ea..001c560 100644
> > --- a/arch_init.c
> > +++ b/arch_init.c
> > @@ -41,6 +41,8 @@
> >  #include "gdbstub.h"
> >  #include "hw/smbios.h"
> >
> > +int kvm_allowed = 0;
> > +
> >  #ifdef TARGET_SPARC
> >  int graphic_width = 1024;
> >  int graphic_height = 768;
> > @@ -508,3 +510,21 @@ int xen_available(void)
> >      return 0;
> >  #endif
> >  }
> > +
> > +void enable_kvm(void)
> > +{
> > +    kvm_allowed = 1;
> > +}
> >
> >
>
>  Can we get away with keeping a local to vl.c use_kvm flag and then call
> kvm_init() if use_kvm in vl.c?

It will not be safe to use kvm_enabled() in vl.c, so there needs to be
a target dependent helper. The call to kvm_init could remain in vl.c,
likewise it's not strictly needed to move kvm_allowed to arch_init.c.
They just caused problems with the poisoning check in patch 2/2. But
with this approach, because kvm.h is no longer included, there will
not be any problems.

>
>  We can stick a stub kvm_init() in arch_init.c if !CONFIG_KVM.
>
>  Regards,
>
>  Anthony LIguori
>
>
>
> > +void kvm_maybe_init(int smp_cpus)
> > +{
> > +    if (kvm_enabled()) {
> > +        int ret;
> > +
> > +        ret = kvm_init(smp_cpus);
> > +        if (ret<  0) {
> > +            fprintf(stderr, "failed to initialize KVM\n");
> > +            exit(1);
> > +        }
> > +    }
> > +}
> > diff --git a/arch_init.h b/arch_init.h
> > index 682890c..dde4309 100644
> > --- a/arch_init.h
> > +++ b/arch_init.h
> > @@ -29,5 +29,7 @@ void cpudef_init(void);
> >  int audio_available(void);
> >  int kvm_available(void);
> >  int xen_available(void);
> > +void enable_kvm(void);
> > +void kvm_maybe_init(int smp_cpus);
> >
> >  #endif
> > diff --git a/vl.c b/vl.c
> > index 03fccbf..cc214dd 100644
> > --- a/vl.c
> > +++ b/vl.c
> > @@ -145,7 +145,6 @@ int main(int argc, char **argv)
> >  #include "dma.h"
> >  #include "audio/audio.h"
> >  #include "migration.h"
> > -#include "kvm.h"
> >  #include "balloon.h"
> >  #include "qemu-option.h"
> >  #include "qemu-config.h"
> > @@ -241,7 +240,6 @@ uint8_t qemu_uuid[16];
> >  static QEMUBootSetHandler *boot_set_handler;
> >  static void *boot_set_opaque;
> >
> > -int kvm_allowed = 0;
> >  uint32_t xen_domid;
> >  enum xen_mode xen_mode = XEN_EMULATE;
> >
> > @@ -3228,7 +3226,7 @@ int main(int argc, char **argv, char **envp)
> >                      printf("Option %s not supported for this
> > target\n", popt->name);
> >                      exit(1);
> >                  }
> > -                kvm_allowed = 1;
> > +                enable_kvm();
> >                  break;
> >              case QEMU_OPTION_usb:
> >                  usb_enabled = 1;
> > @@ -3574,15 +3572,7 @@ int main(int argc, char **argv, char **envp)
> >          exit(1);
> >      }
> >
> > -    if (kvm_enabled()) {
> > -        int ret;
> > -
> > -        ret = kvm_init(smp_cpus);
> > -        if (ret<  0) {
> > -            fprintf(stderr, "failed to initialize KVM\n");
> > -            exit(1);
> > -        }
> > -    }
> > +    kvm_maybe_init(smp_cpus);
> >
> >      if (qemu_init_main_loop()) {
> >          fprintf(stderr, "qemu_init_main_loop failed\n");
> >
> >
>
>

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Paolo Bonzini]

[-- Attachment #1: Type: text/plain, Size: 1173 bytes --]

On 04/01/2010 10:27 PM, Blue Swirl wrote:
> It will not be safe to use kvm_enabled() in vl.c, so there needs to be
> a target dependent helper. The call to kvm_init could remain in vl.c,
> likewise it's not strictly needed to move kvm_allowed to arch_init.c.

Not really, because kvm_allowed _can_ be used from once-compiled files. 
  The attached patch makes kvm-all.c be compiled always, even if 
!CONFIG_KVM; functions that require kvm are almost always omitted for 
now (so checking kvm_enabled() is required to call them).  However, 
kvm_init is stubbed so that vl.c can call it.

In the future we could add more stubbing and ultimately do this 
unconditionally:

    #define kvm_enabled() kvm_allowed

With this patch vl.c can already be compiled once, but I did not include 
it because it would conflict with my balloon.c series; I'm doing enough 
rebasing these days.  Also, qemu-kvm is a bit behind qemu and all these 
patches are nightmares for the merges, so it's better IMO if things are 
left to calm down a bit.

> They just caused problems with the poisoning check in patch 2/2.

Poisoning kvm_enabled is right, but poisoning kvm_allowed is overkill.

Paolo

[-- Attachment #2: 0001-provide-a-stub-version-of-kvm-all.c-if-CONFIG_KVM.patch --]
[-- Type: text/plain, Size: 4689 bytes --]

From e9bd21893633365567b7c0d468a9971ab02e46f0 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 2 Apr 2010 09:29:54 +0200
Subject: [PATCH] provide a stub version of kvm-all.c if !CONFIG_KVM

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>
---
 Makefile.target |    4 ++--
 kvm-all.c       |   16 ++++++++++++++--
 kvm.h           |    4 +++-
 vl.c            |   16 +++++++---------
 4 files changed, 26 insertions(+), 14 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 167fc8d..3943de1 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -168,8 +168,8 @@ obj-y += virtio-blk.o virtio-balloon.o virtio-net.o virtio-pci.o virtio-serial-b
 obj-y += event_notifier.o
 obj-y += vhost_net.o
 obj-$(CONFIG_VHOST_NET) += vhost.o
-obj-y += rwhandler.o
-obj-$(CONFIG_KVM) += kvm.o kvm-all.o
+obj-y += rwhandler.o kvm-all.o
+obj-$(CONFIG_KVM) += kvm.o
 LIBS+=-lz
 
 QEMU_CFLAGS += $(VNC_TLS_CFLAGS)
diff --git a/kvm-all.c b/kvm-all.c
index 7aa5e57..53f58a6 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -13,14 +13,16 @@
  *
  */
 
+#include "qemu-common.h"
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/mman.h>
 #include <stdarg.h>
 
+#ifdef CONFIG_KVM
 #include <linux/kvm.h>
+#endif
 
-#include "qemu-common.h"
 #include "qemu-barrier.h"
 #include "sysemu.h"
 #include "hw/hw.h"
@@ -73,6 +75,7 @@ struct KVMState
 
 static KVMState *kvm_state;
 
+#ifdef CONFIG_KVM
 static KVMSlot *kvm_alloc_slot(KVMState *s)
 {
     int i;
@@ -282,7 +285,7 @@ static int kvm_set_migration_log(int enable)
     return 0;
 }
 
-static int test_le_bit(unsigned long nr, unsigned char *addr)
+static inline int test_le_bit(unsigned long nr, unsigned char *addr)
 {
     return (addr[nr >> 3] >> (nr & 7)) & 1;
 }
@@ -561,9 +564,11 @@ static CPUPhysMemoryClient kvm_cpu_phys_memory_client = {
 	.sync_dirty_bitmap = kvm_client_sync_dirty_bitmap,
 	.migration_log = kvm_client_migration_log,
 };
+#endif
 
 int kvm_init(int smp_cpus)
 {
+#ifdef CONFIG_KVM
     static const char upgrade_note[] =
         "Please upgrade to at least kernel 2.6.29 or recent kvm-kmod\n"
         "(see http://sourceforge.net/projects/kvm).\n";
@@ -683,8 +688,12 @@ err:
     qemu_free(s);
 
     return ret;
+#else
+    return -ENOSYS;
+#endif
 }
 
+#ifdef CONFIG_KVM
 static int kvm_handle_io(uint16_t port, void *data, int direction, int size,
                          uint32_t count)
 {
@@ -866,6 +875,7 @@ int kvm_cpu_exec(CPUState *env)
 
     return ret;
 }
+#endif
 
 int kvm_ioctl(KVMState *s, int type, ...)
 {
@@ -1139,6 +1149,7 @@ void kvm_remove_all_breakpoints(CPUState *current_env)
 }
 #endif /* !KVM_CAP_SET_GUEST_DEBUG */
 
+#ifdef CONFIG_KVM
 int kvm_set_signal_mask(CPUState *env, const sigset_t *sigset)
 {
     struct kvm_signal_mask *sigmask;
@@ -1156,6 +1167,7 @@ int kvm_set_signal_mask(CPUState *env, const sigset_t *sigset)
 
     return r;
 }
+#endif
 
 #ifdef KVM_IOEVENTFD
 int kvm_set_ioeventfd_pio_word(int fd, uint16_t addr, uint16_t val, bool assign)
diff --git a/kvm.h b/kvm.h
index 1e5be27..2477cfd 100644
--- a/kvm.h
+++ b/kvm.h
@@ -18,13 +18,15 @@
 #include <errno.h>
 #include "config-host.h"
 #include "qemu-queue.h"
+#include "cpu-common.h"
 
 #ifdef CONFIG_KVM
 #include <linux/kvm.h>
 #endif
 
-#ifdef CONFIG_KVM
 extern int kvm_allowed;
+
+#ifdef CONFIG_KVM
 #define kvm_enabled() (kvm_allowed)
 #else
 #define kvm_enabled() (0)
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

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Anthony Liguori]

On 04/02/2010 10:01 AM, Paolo Bonzini wrote:
> On 04/01/2010 10:27 PM, Blue Swirl wrote:
>> It will not be safe to use kvm_enabled() in vl.c, so there needs to be
>> a target dependent helper. The call to kvm_init could remain in vl.c,
>> likewise it's not strictly needed to move kvm_allowed to arch_init.c.
>
> Not really, because kvm_allowed _can_ be used from once-compiled 
> files.  The attached patch makes kvm-all.c be compiled always, even if 
> !CONFIG_KVM; functions that require kvm are almost always omitted for 
> now (so checking kvm_enabled() is required to call them).  However, 
> kvm_init is stubbed so that vl.c can call it.
>
> In the future we could add more stubbing and ultimately do this 
> unconditionally:
>
>    #define kvm_enabled() kvm_allowed
>
> With this patch vl.c can already be compiled once, but I did not 
> include it because it would conflict with my balloon.c series; I'm 
> doing enough rebasing these days.  Also, qemu-kvm is a bit behind qemu 
> and all these patches are nightmares for the merges, so it's better 
> IMO if things are left to calm down a bit.

Having kvm-all.c compile with and without CONFIG_KVM is pretty ugly IMHO.

Is compiling vl.c once really that important of a goal?  Wouldn't it be 
better to split bits out of vl.c and have those compile once?  Ideally, 
vl.c should be so small that compiling per-target shouldn't matter.

Regards,

Anthony Liguori

>> They just caused problems with the poisoning check in patch 2/2.
>
> Poisoning kvm_enabled is right, but poisoning kvm_allowed is overkill.
>
> Paolo

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Paolo Bonzini]

On 04/02/2010 05:08 PM, Anthony Liguori wrote:
> Having kvm-all.c compile with and without CONFIG_KVM is pretty ugly IMHO.
>
> Is compiling vl.c once really that important of a goal?

I didn't do this to compile vl.c once.  I don't care about that.

I did this as an initial step towards having kvm functions stubbed out 
for !CONFIG_KVM, instead of relying on GCC performing 
dead-code-elimination on kvm_enabled().

Paolo

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Anthony Liguori]

On 04/02/2010 10:11 AM, Paolo Bonzini wrote:
> On 04/02/2010 05:08 PM, Anthony Liguori wrote:
>> Having kvm-all.c compile with and without CONFIG_KVM is pretty ugly 
>> IMHO.
>>
>> Is compiling vl.c once really that important of a goal?
>
> I didn't do this to compile vl.c once.  I don't care about that.
>
> I did this as an initial step towards having kvm functions stubbed out 
> for !CONFIG_KVM, instead of relying on GCC performing 
> dead-code-elimination on kvm_enabled().

I'd prefer a kvm-stub.c implementation as opposed to mixing in 
CONFIG_KVM in kvm-all.c

Regards,

Anthony Liguori

> Paolo

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Paolo Bonzini]

On 04/02/2010 05:20 PM, Anthony Liguori wrote:
>>
>> I didn't do this to compile vl.c once.  I don't care about that.
>>
>> I did this as an initial step towards having kvm functions stubbed out
>> for !CONFIG_KVM, instead of relying on GCC performing
>> dead-code-elimination on kvm_enabled().
>
> I'd prefer a kvm-stub.c implementation as opposed to mixing in
> CONFIG_KVM in kvm-all.c

I tried it, but our build system makes it a mess because 
compile-once-only can only be done using what once were static 
libraries.  All files from there are added blindly:

    obj-y += $(addprefix ../, $(common-obj-y))
    obj-y += $(addprefix ../libdis/, $(libdis-y))
    obj-y += $(libobj-y)
    obj-y += $(addprefix $(HWDIR)/, $(hw-obj-y))

I'll try something.

Paolo

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Blue Swirl]

On 4/2/10, Anthony Liguori <anthony@codemonkey.ws> wrote:
> On 04/02/2010 10:01 AM, Paolo Bonzini wrote:
>
> > On 04/01/2010 10:27 PM, Blue Swirl wrote:
> >
> > > It will not be safe to use kvm_enabled() in vl.c, so there needs to be
> > > a target dependent helper. The call to kvm_init could remain in vl.c,
> > > likewise it's not strictly needed to move kvm_allowed to arch_init.c.
> > >
> >
> > Not really, because kvm_allowed _can_ be used from once-compiled files.
> The attached patch makes kvm-all.c be compiled always, even if !CONFIG_KVM;
> functions that require kvm are almost always omitted for now (so checking
> kvm_enabled() is required to call them).  However, kvm_init is stubbed so
> that vl.c can call it.
> >
> > In the future we could add more stubbing and ultimately do this
> unconditionally:
> >
> >   #define kvm_enabled() kvm_allowed
> >
> > With this patch vl.c can already be compiled once, but I did not include
> it because it would conflict with my balloon.c series; I'm doing enough
> rebasing these days.  Also, qemu-kvm is a bit behind qemu and all these
> patches are nightmares for the merges, so it's better IMO if things are left
> to calm down a bit.
> >
>
>  Having kvm-all.c compile with and without CONFIG_KVM is pretty ugly IMHO.
>
>  Is compiling vl.c once really that important of a goal?  Wouldn't it be
> better to split bits out of vl.c and have those compile once?  Ideally, vl.c
> should be so small that compiling per-target shouldn't matter.

But the only thing preventing compiling whole vl.c once is just KVM
init. I'll send a new patch, hopefully it's better.

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Paolo Bonzini]

On 04/01/2010 10:07 PM, Blue Swirl wrote:
> Remove dependency of vl.c to KVM, then we can partially revert
> b33612d03540fda7fa67485f1c20395beb7a2bf0.

This is ugly...

Michael Tsirkin said in commit ca821806:

  Comment on kvm usage: rather than require users to do if(kvm_enabled())
  and/or ifdefs, this patch adds an API that, internally, is defined to
  stub function on non-kvm build, and checks kvm_enabled for non-kvm
  run.

  While rest of qemu code still uses if (kvm_enabled()), I think this
  approach is cleaner, and we should convert rest of code to it
  long term.

Maybe we can start doing this for kvm_init?

> +void enable_kvm(void)
> +{
> +    kvm_allowed = 1;
> +}

If you're adding this, this conditional from vl.c

  if (!(kvm_available())) {
      printf("Option %s not supported for this target\n", popt->name);
      exit(1);
  }

belongs in arch_init.c too, like in do_smbios_option and 
do_acpitable_option.

Alternatively, with the approach I gave above, you can test in 
kvm_maybe_init if kvm_init returns -ENOSYS, and print the error above 
instead of "failed to initialize KVM".

Paolo

[Qemu-devel] Re: [PATCH 1/2] Move KVM init to arch_init.c, compile vl.c once

[Blue Swirl]

On 4/1/10, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 04/01/2010 10:07 PM, Blue Swirl wrote:
>
> > Remove dependency of vl.c to KVM, then we can partially revert
> > b33612d03540fda7fa67485f1c20395beb7a2bf0.
> >
>
>  This is ugly...
>
>  Michael Tsirkin said in commit ca821806:
>
>   Comment on kvm usage: rather than require users to do if(kvm_enabled())
>   and/or ifdefs, this patch adds an API that, internally, is defined to
>   stub function on non-kvm build, and checks kvm_enabled for non-kvm
>   run.
>
>   While rest of qemu code still uses if (kvm_enabled()), I think this
>   approach is cleaner, and we should convert rest of code to it
>   long term.
>
>  Maybe we can start doing this for kvm_init?

I see now. Yes, this would be better approach, I think this is also
what Anthony proposed.

> > +void enable_kvm(void)
> > +{
> > +    kvm_allowed = 1;
> > +}
> >
>
>  If you're adding this, this conditional from vl.c
>
>   if (!(kvm_available())) {
>      printf("Option %s not supported for this target\n", popt->name);
>      exit(1);
>   }
>
>  belongs in arch_init.c too, like in do_smbios_option and
> do_acpitable_option.
>
>  Alternatively, with the approach I gave above, you can test in
> kvm_maybe_init if kvm_init returns -ENOSYS, and print the error above
> instead of "failed to initialize KVM".

Also kvm_allowed could be set in kvm-all.c.