RE: [PATCH 2/2] xen: cleanup unrealized flash devices

[Paul Durrant <xadimgnik@gmail.com>]

> -----Original Message-----
> From: Philippe Mathieu-Daudé <philmd@redhat.com>
> Sent: 30 June 2020 16:26
> To: Paul Durrant <paul@xen.org>; xen-devel@lists.xenproject.org; qemu-devel@nongnu.org
> Cc: Eduardo Habkost <ehabkost@redhat.com>; Michael S. Tsirkin <mst@redhat.com>; Paul Durrant
> <pdurrant@amazon.com>; Jason Andryuk <jandryuk@gmail.com>; Paolo Bonzini <pbonzini@redhat.com>;
> Richard Henderson <rth@twiddle.net>
> Subject: Re: [PATCH 2/2] xen: cleanup unrealized flash devices
> 
> On 6/24/20 2:18 PM, Paul Durrant wrote:
> > From: Paul Durrant <pdurrant@amazon.com>
> >
> > The generic pc_machine_initfn() calls pc_system_flash_create() which creates
> > 'system.flash0' and 'system.flash1' devices. These devices are then realized
> > by pc_system_flash_map() which is called from pc_system_firmware_init() which
> > itself is called via pc_memory_init(). The latter however is not called when
> > xen_enable() is true and hence the following assertion fails:
> >
> > qemu-system-i386: hw/core/qdev.c:439: qdev_assert_realized_properly:
> > Assertion `dev->realized' failed
> >
> > These flash devices are unneeded when using Xen so this patch avoids the
> > assertion by simply removing them using pc_system_flash_cleanup_unused().
> >
> > Reported-by: Jason Andryuk <jandryuk@gmail.com>
> > Fixes: ebc29e1beab0 ("pc: Support firmware configuration with -blockdev")
> > Signed-off-by: Paul Durrant <pdurrant@amazon.com>
> > Tested-by: Jason Andryuk <jandryuk@gmail.com>
> > ---
> > Cc: Paolo Bonzini <pbonzini@redhat.com>
> > Cc: Richard Henderson <rth@twiddle.net>
> > Cc: Eduardo Habkost <ehabkost@redhat.com>
> > Cc: "Michael S. Tsirkin" <mst@redhat.com>
> > Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> > ---
> >  hw/i386/pc_piix.c    | 9 ++++++---
> >  hw/i386/pc_sysfw.c   | 2 +-
> >  include/hw/i386/pc.h | 1 +
> >  3 files changed, 8 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index 1497d0e4ae..977d40afb8 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -186,9 +186,12 @@ static void pc_init1(MachineState *machine,
> >      if (!xen_enabled()) {
> >          pc_memory_init(pcms, system_memory,
> >                         rom_memory, &ram_memory);
> > -    } else if (machine->kernel_filename != NULL) {
> > -        /* For xen HVM direct kernel boot, load linux here */
> > -        xen_load_linux(pcms);
> > +    } else {
> > +        pc_system_flash_cleanup_unused(pcms);
> 
> TIL pc_system_flash_cleanup_unused().
> 
> What about restricting at the source?
>

And leave the devices in place? They are not relevant for Xen, so why not clean up?

  Paul
 
> -- >8 --
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1004,24 +1004,26 @@ void pc_memory_init(PCMachineState *pcms,
>                                      &machine->device_memory->mr);
>      }
> 
> -    /* Initialize PC system firmware */
> -    pc_system_firmware_init(pcms, rom_memory);
> -
> -    option_rom_mr = g_malloc(sizeof(*option_rom_mr));
> -    memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE,
> -                           &error_fatal);
> -    if (pcmc->pci_enabled) {
> -        memory_region_set_readonly(option_rom_mr, true);
> -    }
> -    memory_region_add_subregion_overlap(rom_memory,
> -                                        PC_ROM_MIN_VGA,
> -                                        option_rom_mr,
> -                                        1);
> -
>      fw_cfg = fw_cfg_arch_create(machine,
>                                  x86ms->boot_cpus, x86ms->apic_id_limit);
> 
> -    rom_set_fw(fw_cfg);
> +    /* Initialize PC system firmware */
> +    if (!xen_enabled()) {
> +        pc_system_firmware_init(pcms, rom_memory);
> +
> +        option_rom_mr = g_malloc(sizeof(*option_rom_mr));
> +        memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE,
> +                               &error_fatal);
> +        if (pcmc->pci_enabled) {
> +            memory_region_set_readonly(option_rom_mr, true);
> +        }
> +        memory_region_add_subregion_overlap(rom_memory,
> +                                            PC_ROM_MIN_VGA,
> +                                            option_rom_mr,
> +                                            1);
> +
> +        rom_set_fw(fw_cfg);
> +    }
> 
>      if (pcmc->has_reserved_memory && machine->device_memory->base) {
>          uint64_t *val = g_malloc(sizeof(*val));
> ---
> 
> > +        if (machine->kernel_filename != NULL) {
> > +            /* For xen HVM direct kernel boot, load linux here */
> > +            xen_load_linux(pcms);
> > +        }
> >      }
> >
> >      gsi_state = pc_gsi_create(&x86ms->gsi, pcmc->pci_enabled);
> > diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> > index ec2a3b3e7e..0ff47a4b59 100644
> > --- a/hw/i386/pc_sysfw.c
> > +++ b/hw/i386/pc_sysfw.c
> > @@ -108,7 +108,7 @@ void pc_system_flash_create(PCMachineState *pcms)
> >      }
> >  }
> >
> > -static void pc_system_flash_cleanup_unused(PCMachineState *pcms)
> > +void pc_system_flash_cleanup_unused(PCMachineState *pcms)
> >  {
> >      char *prop_name;
> >      int i;
> > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > index e6135c34d6..497f2b7ab7 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -187,6 +187,7 @@ int cmos_get_fd_drive_type(FloppyDriveType fd0);
> >
> >  /* pc_sysfw.c */
> >  void pc_system_flash_create(PCMachineState *pcms);
> > +void pc_system_flash_cleanup_unused(PCMachineState *pcms);
> >  void pc_system_firmware_init(PCMachineState *pcms, MemoryRegion *rom_memory);
> >
> >  /* acpi-build.c */
> >