[Qemu-devel] [PATCH 0/2] Remove hardcoded xen-platform device initialization (v3)

[Qemu-devel] [PATCH 0/2] Remove hardcoded xen-platform device initialization (v3)

[Paul Durrant]

Because of concerns over backwards compatibility and a suggestion that
xenfv should be retired in favour of using the pc machine type I have re-
worked my original patch into 2 patches:

[PATCH 1/2] Allow use of pc machine type (accel=xen) for Xen HVM
[PATCH 2/2] Move hardcoded initialization of xen-platform device.

Application of both these patches allows alternative pc machine types to be
used with the accel=xen option, but preserves the hardcoded creation of
the xen-platform device only for machine type xenfv.

v3:
- Add test for xen_enabled() that went missing in v2

[Qemu-devel] [PATCH 1/2] Allow use of pc machine type (accel=xen) for Xen HVM domains.

[Paul Durrant]

Xen HVM domains normally spawn QEMU with a dedicated xenfv machine type. The
initialization code for this machine type can easily be pulled into the
generic pc initialization code and guarded with a test for whether the xen
accelerator options is specified, which is more consistent with the way
other accelerators are used.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
---
 hw/i386/pc_piix.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index d618570..7bbb59a 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -1,3 +1,4 @@
+
 /*
  * QEMU PC System Emulator
  *
@@ -91,6 +92,10 @@ static void pc_init1(MemoryRegion *system_memory,
     DeviceState *icc_bridge;
     FWCfgState *fw_cfg = NULL;
 
+    if (xen_enabled() && xen_hvm_init() != 0) {
+        hw_error("xen hardware virtual machine initialisation failed");
+    }
+
     icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
     object_property_add_child(qdev_get_machine(), "icc-bridge",
                               OBJECT(icc_bridge), NULL);
@@ -320,9 +325,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
 #ifdef CONFIG_XEN
 static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
 {
-    if (xen_hvm_init() != 0) {
-        hw_error("xen hardware virtual machine initialisation failed");
-    }
     pc_init_pci(args);
 }
 #endif
-- 
1.7.10.4

Re: [Qemu-devel] [PATCH 1/2] Allow use of pc machine type (accel=xen) for Xen HVM domains.

[Andreas Färber]

Am 18.06.2013 11:59, schrieb Paul Durrant:
> Xen HVM domains normally spawn QEMU with a dedicated xenfv machine type. The
> initialization code for this machine type can easily be pulled into the
> generic pc initialization code and guarded with a test for whether the xen
> accelerator options is specified, which is more consistent with the way
> other accelerators are used.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> ---
>  hw/i386/pc_piix.c |    8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index d618570..7bbb59a 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -1,3 +1,4 @@
> +
>  /*
>   * QEMU PC System Emulator
>   *

Unrelated whitespace change, please drop this hunk.

> @@ -91,6 +92,10 @@ static void pc_init1(MemoryRegion *system_memory,
>      DeviceState *icc_bridge;
>      FWCfgState *fw_cfg = NULL;
>  
> +    if (xen_enabled() && xen_hvm_init() != 0) {
> +        hw_error("xen hardware virtual machine initialisation failed");

I see this is just a code movement, but maybe consider replacing that
with an fprintf()+exit(1)? Xen does not have any CPUs AFAIU and they
wouldn't be initialized at that point anyway, so hw_error() is not much
more than an fprintf()+abort().

Regards,
Andreas

> +    }
> +
>      icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
>      object_property_add_child(qdev_get_machine(), "icc-bridge",
>                                OBJECT(icc_bridge), NULL);
> @@ -320,9 +325,6 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
>  #ifdef CONFIG_XEN
>  static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
>  {
> -    if (xen_hvm_init() != 0) {
> -        hw_error("xen hardware virtual machine initialisation failed");
> -    }
>      pc_init_pci(args);
>  }
>  #endif

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg

Re: [Qemu-devel] [PATCH 1/2] Allow use of pc machine type (accel=xen) for Xen HVM domains.

[Paul Durrant]

> -----Original Message-----
> From: Andreas Färber [mailto:afaerber@suse.de]
> Sent: 18 June 2013 11:29
> To: Paul Durrant
> Cc: qemu-devel@nongnu.org; xen-devel@lists.xen.org; Paolo Bonzini
> Subject: Re: [Qemu-devel] [PATCH 1/2] Allow use of pc machine type
> (accel=xen) for Xen HVM domains.
> 
> Am 18.06.2013 11:59, schrieb Paul Durrant:
> > Xen HVM domains normally spawn QEMU with a dedicated xenfv machine
> type. The
> > initialization code for this machine type can easily be pulled into the
> > generic pc initialization code and guarded with a test for whether the xen
> > accelerator options is specified, which is more consistent with the way
> > other accelerators are used.
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> > ---
> >  hw/i386/pc_piix.c |    8 +++++---
> >  1 file changed, 5 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index d618570..7bbb59a 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -1,3 +1,4 @@
> > +
> >  /*
> >   * QEMU PC System Emulator
> >   *
> 
> Unrelated whitespace change, please drop this hunk.
> 

Ok.

> > @@ -91,6 +92,10 @@ static void pc_init1(MemoryRegion
> *system_memory,
> >      DeviceState *icc_bridge;
> >      FWCfgState *fw_cfg = NULL;
> >
> > +    if (xen_enabled() && xen_hvm_init() != 0) {
> > +        hw_error("xen hardware virtual machine initialisation failed");
> 
> I see this is just a code movement, but maybe consider replacing that
> with an fprintf()+exit(1)? Xen does not have any CPUs AFAIU and they
> wouldn't be initialized at that point anyway, so hw_error() is not much
> more than an fprintf()+abort().
> 

If that's preferred I can do that, but it makes it less apparent that this patch is just code movement.

  Paul

[Qemu-devel] [PATCH 2/2] Move hardcoded initialization of xen-platform device.

[Paul Durrant]

Creation of the xen-platform device is currently hardcoded into machine
type pc's initialization code, guarded by a test for the whether the xen
accelerator is enabled. This patch moves the creation of xen-platform into
the initialization code of the xenfv machine type. This maintains backwards
compatibility for that machine type but allows more flexibility if another
machine type is used with Xen HVM domains.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
---
 hw/i386/pc_piix.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 7bbb59a..8dd487e 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -179,9 +179,6 @@ static void pc_init1(MemoryRegion *system_memory,
     pc_register_ferr_irq(gsi[13]);
 
     pc_vga_init(isa_bus, pci_enabled ? pci_bus : NULL);
-    if (xen_enabled()) {
-        pci_create_simple(pci_bus, -1, "xen-platform");
-    }
 
     /* init basic PC hardware */
     pc_basic_device_init(isa_bus, gsi, &rtc_state, &floppy, xen_enabled());
@@ -325,7 +322,13 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
 #ifdef CONFIG_XEN
 static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
 {
+    PCIBus *bus;
+
     pc_init_pci(args);
+
+    bus = pci_find_root_bus(0);
+    if (bus != NULL)
+        pci_create_simple(bus, -1, "xen-platform");
 }
 #endif
 
-- 
1.7.10.4

Re: [Qemu-devel] [PATCH 2/2] Move hardcoded initialization of xen-platform device.

[Andreas Färber]

Am 18.06.2013 11:59, schrieb Paul Durrant:
> Creation of the xen-platform device is currently hardcoded into machine
> type pc's initialization code, guarded by a test for the whether the xen
> accelerator is enabled. This patch moves the creation of xen-platform into
> the initialization code of the xenfv machine type. This maintains backwards
> compatibility for that machine type but allows more flexibility if another
> machine type is used with Xen HVM domains.
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> ---
>  hw/i386/pc_piix.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 7bbb59a..8dd487e 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -179,9 +179,6 @@ static void pc_init1(MemoryRegion *system_memory,
>      pc_register_ferr_irq(gsi[13]);
>  
>      pc_vga_init(isa_bus, pci_enabled ? pci_bus : NULL);
> -    if (xen_enabled()) {
> -        pci_create_simple(pci_bus, -1, "xen-platform");
> -    }
>  
>      /* init basic PC hardware */
>      pc_basic_device_init(isa_bus, gsi, &rtc_state, &floppy, xen_enabled());
> @@ -325,7 +322,13 @@ static void pc_init_isa(QEMUMachineInitArgs *args)
>  #ifdef CONFIG_XEN
>  static void pc_xen_hvm_init(QEMUMachineInitArgs *args)
>  {
> +    PCIBus *bus;
> +
>      pc_init_pci(args);
> +
> +    bus = pci_find_root_bus(0);
> +    if (bus != NULL)
> +        pci_create_simple(bus, -1, "xen-platform");

scripts/checkpatch.pl will complain about missing braces for if, but
otherwise looks okay to me.

Andreas

>  }
>  #endif
>  

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg