Re: [Qemu-devel] [PATCH 03/27] pc: add 'etc/reserved-memory-end' fw_cfg interface for SeaBIOS

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Dec 20, 2013 at 01:48:47PM +0100, Igor Mammedov wrote:
> On Thu, 19 Dec 2013 16:35:05 +0200
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
> 
> > On Thu, Nov 21, 2013 at 03:38:24AM +0100, Igor Mammedov wrote:
> > > 'etc/reserved-memory-end' will allow QEMU to tell BIOS where PCI
> > > BARs mapping could safely start in high memory.
> > > 
> > > Allowing BIOS to start mapping 64-bit PCI BARs at address where it
> > > wouldn't conflict with other mappings QEMU might place before it.
> > > 
> > > That permits QEMU to reserve extra address space before
> > > 64-bit PCI hole for memory hotplug.
> > > 
> > > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > > ---
> > > v2:
> > >    * disable 'etc/reserved-memory-end' for 1.7 and older machine types
> > > ---
> > >  hw/i386/pc.c         |   27 +++++++++++++++++++++++++--
> > >  hw/i386/pc_piix.c    |    1 +
> > >  hw/i386/pc_q35.c     |    1 +
> > >  hw/pci-host/piix.c   |    3 ++-
> > >  hw/pci-host/q35.c    |    3 ++-
> > >  include/hw/i386/pc.h |   11 +++++++++--
> > >  6 files changed, 40 insertions(+), 6 deletions(-)
> > > 
> > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > > index 6c82ada..ba82c67 100644
> > > --- a/hw/i386/pc.c
> > > +++ b/hw/i386/pc.c
> > > @@ -1094,14 +1094,37 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
> > >  }
> > >  
> > >  /* setup pci memory address space mapping into system address space */
> > > -void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> > > -                            MemoryRegion *pci_address_space)
> > > +void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
> > > +                                MemoryRegion *pci_address_space,
> > > +                                uint64_t reserved_memory_end)
> > >  {
> > >      /* Set to lower priority than RAM */
> > >      memory_region_add_subregion_overlap(system_memory, 0x0,
> > >                                          pci_address_space, -1);
> > >  }
> > >  
> > > +static
> > > +void pc_pci_as_mapping_init_1_8(Object *owner, MemoryRegion *system_memory,
> > > +                                MemoryRegion *pci_address_space,
> > > +                                uint64_t reserved_memory_end)
> > > +{
> > > +    uint64_t *val;
> > > +    FWCfgState *fw_cfg = fw_cfg_find();
> > > +    g_assert(fw_cfg);
> > > +    /*
> > > +     *  Align address at 1G, this makes sure it can be exactly covered
> > > +     *  with a PAT entry even when using huge pages.
> > > +     */
> > > +    val = g_malloc(sizeof(*val));
> > > +    *val = cpu_to_le64(ROUND_UP(reserved_memory_end, 0x1ULL << 30));
> > > +    fw_cfg_add_file(fw_cfg, "etc/reserved-memory-end", val, sizeof(*val));
> > > +
> > > +    pc_pci_as_mapping_init_1_7(owner, system_memory, pci_address_space,
> > > +                               reserved_memory_end);
> > > +}
> > > +
> > > +pc_pci_as_mapping_init_fn pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_8;
> > > +
> > >  void pc_acpi_init(const char *default_dsdt)
> > >  {
> > >      char *filename;
> > > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > > index 36f2495..e1fe85a 100644
> > > --- a/hw/i386/pc_piix.c
> > > +++ b/hw/i386/pc_piix.c
> > > @@ -249,6 +249,7 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
> > >  static void pc_compat_1_7(QEMUMachineInitArgs *args)
> > >  {
> > >      smbios_type1_defaults = false;
> > > +    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
> > >  }
> > >  
> > >  static void pc_compat_1_6(QEMUMachineInitArgs *args)
> > > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > > index 50ca458..5525465 100644
> > > --- a/hw/i386/pc_q35.c
> > > +++ b/hw/i386/pc_q35.c
> > > @@ -233,6 +233,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
> > >  static void pc_compat_1_7(QEMUMachineInitArgs *args)
> > >  {
> > >      smbios_type1_defaults = false;
> > > +    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
> > >  }
> > >  
> > >  static void pc_compat_1_6(QEMUMachineInitArgs *args)
> > 
> > I don't much like this: why not use a global flag like we do
> > for other properties?
> because flag would add extra branching clattering code, while
> overriding function makes caller cleaner and potentially maps
> well into method override when machines are converted to QOM objects.
> So why not to try this vs flags?

For consistency with other code. We have too many unfinished
conversions across the codebase, they are a bigger problem
than some branches here and there.

So I would say let's delay these experiments until this QOM
cleanup happens.

> > 
> > Also, 1_8 should be replaced with 2_0 now.
> sure
> 
> > 
> > > diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> > > index 63be7f6..615ab0d 100644
> > > --- a/hw/pci-host/piix.c
> > > +++ b/hw/pci-host/piix.c
> > > @@ -352,7 +352,8 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
> > >  
> > >      /* setup pci memory mapping */
> > >      pc_pci_as_mapping_init(OBJECT(f), f->system_memory,
> > > -                           f->pci_address_space);
> > > +                           f->pci_address_space,
> > > +                           0x100000000ULL + above_4g_mem_size);
> > >  
> > >      memory_region_init_alias(&f->smram_region, OBJECT(d), "smram-region",
> > >                               f->pci_address_space, 0xa0000, 0x20000);
> > > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > > index 81c8240..6e28418 100644
> > > --- a/hw/pci-host/q35.c
> > > +++ b/hw/pci-host/q35.c
> > > @@ -359,7 +359,8 @@ static int mch_init(PCIDevice *d)
> > >  
> > >      /* setup pci memory mapping */
> > >      pc_pci_as_mapping_init(OBJECT(mch), mch->system_memory,
> > > -                           mch->pci_address_space);
> > > +                           mch->pci_address_space,
> > > +                           0x100000000ULL + mch->above_4g_mem_size);
> > >  
> > >      /* smram */
> > >      cpu_smm_register(&mch_set_smm, mch);
> > > diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> > > index 9af09d3..c4e8048 100644
> > > --- a/include/hw/i386/pc.h
> > > +++ b/include/hw/i386/pc.h
> > > @@ -129,8 +129,15 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
> > >  #define DEFAULT_PCI_HOLE64_SIZE (~0x0ULL)
> > >  
> > >  
> > > -void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> > > -                            MemoryRegion *pci_address_space);
> > > +typedef
> > > +void (*pc_pci_as_mapping_init_fn)(Object *owner, MemoryRegion *system_memory,
> > > +                                  MemoryRegion *pci_address_space,
> > > +                                  uint64_t reserved_memory_end);
> > > +extern pc_pci_as_mapping_init_fn pc_pci_as_mapping_init;
> > > +
> > > +void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
> > > +                                MemoryRegion *pci_address_space,
> > > +                                uint64_t reserved_memory_end);
> > >  
> > >  FWCfgState *pc_memory_init(MemoryRegion *system_memory,
> > >                             const char *kernel_filename,
> > > -- 
> > > 1.7.1
> >