On Tue, Nov 12, 2013 at 07:26:02PM +0100, Paolo Bonzini wrote:
> Il 12/11/2013 14:58, Igor Mammedov ha scritto:
> > '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.
>
> I may be royally wrong, but I think the new file should only be added to
> new machine types. Otherwise, after migrating old machine types from
> new QEMU to old QEMU, you may end up with PCI BARs mapped outside the
> "PCI windows" that exist until before patch 1/2 of this series.
>
> Does this make sense?
Yes.
Generally FW CFG must not be added/removed for a given machine types,
otherwise guest that is migrated while reading it will
get a corrupted result: half old and half new.
> Also, would it make sense to use the e820 interface that Gerd has added,
> instead of a new fw_cfg file?
>
> Thanks,
>
> Paolo
This was already discussed on previous revisions of this patch.
Have you seen that discussion?
>
> > Signed-off-by: Igor Mammedov <imamm...@redhat.com>
> > ---
> > hw/i386/pc.c | 14 +++++++++++++-
> > hw/pci-host/piix.c | 3 ++-
> > hw/pci-host/q35.c | 3 ++-
> > include/hw/i386/pc.h | 3 ++-
> > 4 files changed, 19 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 6c82ada..b504047 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1095,11 +1095,23 @@ 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)
> > + MemoryRegion *pci_address_space,
> > + uint64_t reserved_memory_end)
> > {
> > + uint64_t *val;
> > + FWCfgState *fw_cfg = fw_cfg_find();
> > +
> > /* Set to lower priority than RAM */
> > memory_region_add_subregion_overlap(system_memory, 0x0,
> > pci_address_space, -1);
> > + 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));
> > }
> >
> > void pc_acpi_init(const char *default_dsdt)
> > diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> > index 5d4e290..16205e7 100644
> > --- a/hw/pci-host/piix.c
> > +++ b/hw/pci-host/piix.c
> > @@ -351,7 +351,8 @@ 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 d1792de..1293353 100644
> > --- a/hw/pci-host/q35.c
> > +++ b/hw/pci-host/q35.c
> > @@ -353,7 +353,8 @@ 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 8b3be3c..2663046 100644
> > --- a/include/hw/i386/pc.h
> > +++ b/include/hw/i386/pc.h
> > @@ -130,7 +130,8 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t
> > below_4g_mem_size,
> >
> >
> > void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> > - MemoryRegion *pci_address_space);
> > + MemoryRegion *pci_address_space,
> > + uint64_t reserved_memory_end);
> >
> > FWCfgState *pc_memory_init(MemoryRegion *system_memory,
> > const char *kernel_filename,
> >
