RE: [PATCH v5] xen: fix build without pci passthrough

[Paul Durrant <xadimgnik@xxxxxxxxx>]

> -----Original Message-----
> From: Xen-devel <xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx> On Behalf Of Anthony 
> PERARD
> Sent: 02 July 2020 15:26
> To: Paul Durrant <paul.durrant@xxxxxxxxxx>

Emails to this address are probably going to /dev/null by now :-)

> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Subject: Re: [PATCH v5] xen: fix build without pci passthrough
> 
> On Thu, Jun 04, 2020 at 02:31:41PM -0400, Paolo Bonzini wrote:
> > From: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> >
> > Xen PCI passthrough support may not be available and thus the global
> > variable "has_igd_gfx_passthru" might be compiled out. Common code
> > should not access it in that case.
> >
> > Unfortunately, we can't use CONFIG_XEN_PCI_PASSTHROUGH directly in
> > xen-common.c so this patch instead move access to the
> > has_igd_gfx_passthru variable via function and those functions are
> > also implemented as stubs. The stubs will be used when QEMU is built
> > without passthrough support.
> >
> > Now, when one will want to enable igd-passthru via the -machine
> > property, they will get an error message if QEMU is built without
> > passthrough support.
> >
> > Fixes: 46472d82322d0 ('xen: convert "-machine igd-passthru" to an 
> > accelerator property')
> > Reported-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> > Signed-off-by: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> > Message-Id: <20200603160442.3151170-1-anthony.perard@xxxxxxxxxx>
> > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> 
> Hi Paul,
> 
> Can I backport this patch to qemu-xen-4.14? It allows to build qemu
> without pci passthrough support which seems to be important for FreeBSD
> as PT with QEMU is only available on Linux.
> 
> (There's a fix to the patch that I would backport as well. "xen:
> Actually fix build without passthrough")
> 
> Thanks.

I have no objection to make this fix for 4.14.

Cheers,

  Paul

> 
> > ---
> >  accel/xen/xen-all.c  |  4 ++--
> >  hw/Makefile.objs     |  2 +-
> >  hw/i386/pc_piix.c    |  2 +-
> >  hw/xen/Makefile.objs |  3 ++-
> >  hw/xen/xen_pt.c      | 12 +++++++++++-
> >  hw/xen/xen_pt.h      |  6 ++++--
> >  hw/xen/xen_pt_stub.c | 22 ++++++++++++++++++++++
> >  7 files changed, 43 insertions(+), 8 deletions(-)
> >  create mode 100644 hw/xen/xen_pt_stub.c
> >
> > diff --git a/accel/xen/xen-all.c b/accel/xen/xen-all.c
> > index f3edc65ec9..0c24d4b191 100644
> > --- a/accel/xen/xen-all.c
> > +++ b/accel/xen/xen-all.c
> > @@ -137,12 +137,12 @@ static void xen_change_state_handler(void *opaque, 
> > int running,
> >
> >  static bool xen_get_igd_gfx_passthru(Object *obj, Error **errp)
> >  {
> > -    return has_igd_gfx_passthru;
> > +    return xen_igd_gfx_pt_enabled();
> >  }
> >
> >  static void xen_set_igd_gfx_passthru(Object *obj, bool value, Error **errp)
> >  {
> > -    has_igd_gfx_passthru = value;
> > +    xen_igd_gfx_pt_set(value, errp);
> >  }
> >
> >  static void xen_setup_post(MachineState *ms, AccelState *accel)
> > diff --git a/hw/Makefile.objs b/hw/Makefile.objs
> > index 660e2b4373..4cbe5e4e57 100644
> > --- a/hw/Makefile.objs
> > +++ b/hw/Makefile.objs
> > @@ -35,7 +35,7 @@ devices-dirs-y += usb/
> >  devices-dirs-$(CONFIG_VFIO) += vfio/
> >  devices-dirs-y += virtio/
> >  devices-dirs-y += watchdog/
> > -devices-dirs-y += xen/
> > +devices-dirs-$(CONFIG_XEN) += xen/
> >  devices-dirs-$(CONFIG_MEM_DEVICE) += mem/
> >  devices-dirs-$(CONFIG_NUBUS) += nubus/
> >  devices-dirs-y += semihosting/
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index eea964e72b..054d3aa9f7 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -377,7 +377,7 @@ static void pc_init_isa(MachineState *machine)
> >  #ifdef CONFIG_XEN
> >  static void pc_xen_hvm_init_pci(MachineState *machine)
> >  {
> > -    const char *pci_type = has_igd_gfx_passthru ?
> > +    const char *pci_type = xen_igd_gfx_pt_enabled() ?
> >                  TYPE_IGD_PASSTHROUGH_I440FX_PCI_DEVICE : 
> > TYPE_I440FX_PCI_DEVICE;
> >
> >      pc_init1(machine,
> > diff --git a/hw/xen/Makefile.objs b/hw/xen/Makefile.objs
> > index 340b2c5096..3fc715e595 100644
> > --- a/hw/xen/Makefile.objs
> > +++ b/hw/xen/Makefile.objs
> > @@ -1,6 +1,7 @@
> >  # xen backend driver support
> > -common-obj-$(CONFIG_XEN) += xen-legacy-backend.o xen_devconfig.o 
> > xen_pvdev.o xen-bus.o xen-bus-
> helper.o xen-backend.o
> > +common-obj-y += xen-legacy-backend.o xen_devconfig.o xen_pvdev.o xen-bus.o 
> > xen-bus-helper.o xen-
> backend.o
> >
> >  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen-host-pci-device.o
> >  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt.o xen_pt_config_init.o 
> > xen_pt_graphics.o xen_pt_msi.o
> >  obj-$(CONFIG_XEN_PCI_PASSTHROUGH) += xen_pt_load_rom.o
> > +obj-$(call $(lnot, $(CONFIG_XEN_PCI_PASSTHROUGH))) += xen_pt_stub.o
> > diff --git a/hw/xen/xen_pt.c b/hw/xen/xen_pt.c
> > index 81d5ad8da7..ab84443d5e 100644
> > --- a/hw/xen/xen_pt.c
> > +++ b/hw/xen/xen_pt.c
> > @@ -65,7 +65,17 @@
> >  #include "qemu/range.h"
> >  #include "exec/address-spaces.h"
> >
> > -bool has_igd_gfx_passthru;
> > +static bool has_igd_gfx_passthru;
> > +
> > +bool xen_igd_gfx_pt_enabled(void)
> > +{
> > +    return has_igd_gfx_passthru;
> > +}
> > +
> > +void xen_igd_gfx_pt_set(bool value, Error **errp)
> > +{
> > +    has_igd_gfx_passthru = value;
> > +}
> >
> >  #define XEN_PT_NR_IRQS (256)
> >  static uint8_t xen_pt_mapped_machine_irq[XEN_PT_NR_IRQS] = {0};
> > diff --git a/hw/xen/xen_pt.h b/hw/xen/xen_pt.h
> > index 179775db7b..6e9cec95f3 100644
> > --- a/hw/xen/xen_pt.h
> > +++ b/hw/xen/xen_pt.h
> > @@ -5,6 +5,9 @@
> >  #include "hw/pci/pci.h"
> >  #include "xen-host-pci-device.h"
> >
> > +bool xen_igd_gfx_pt_enabled(void);
> > +void xen_igd_gfx_pt_set(bool value, Error **errp);
> > +
> >  void xen_pt_log(const PCIDevice *d, const char *f, ...) GCC_FMT_ATTR(2, 3);
> >
> >  #define XEN_PT_ERR(d, _f, _a...) xen_pt_log(d, "%s: Error: "_f, __func__, 
> > ##_a)
> > @@ -322,10 +325,9 @@ extern void *pci_assign_dev_load_option_rom(PCIDevice 
> > *dev,
> >                                              unsigned int domain,
> >                                              unsigned int bus, unsigned int 
> > slot,
> >                                              unsigned int function);
> > -extern bool has_igd_gfx_passthru;
> >  static inline bool is_igd_vga_passthrough(XenHostPCIDevice *dev)
> >  {
> > -    return (has_igd_gfx_passthru
> > +    return (xen_igd_gfx_pt_enabled()
> >              && ((dev->class_code >> 0x8) == PCI_CLASS_DISPLAY_VGA));
> >  }
> >  int xen_pt_register_vga_regions(XenHostPCIDevice *dev);
> > diff --git a/hw/xen/xen_pt_stub.c b/hw/xen/xen_pt_stub.c
> > new file mode 100644
> > index 0000000000..2d8cac8d54
> > --- /dev/null
> > +++ b/hw/xen/xen_pt_stub.c
> > @@ -0,0 +1,22 @@
> > +/*
> > + * Copyright (C) 2020       Citrix Systems UK Ltd.
> > + *
> > + * 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/osdep.h"
> > +#include "hw/xen/xen_pt.h"
> > +#include "qapi/error.h"
> > +
> > +bool xen_igd_gfx_pt_enabled(void)
> > +{
> > +    return false;
> > +}
> > +
> > +void xen_igd_gfx_pt_set(bool value, Error **errp)
> > +{
> > +    if (value) {
> > +        error_setg(errp, "Xen PCI passthrough support not built in");
> > +    }
> > +}
> > --
> > 2.26.2
> >
> >
> 
> --
> Anthony PERARD