Re: [Qemu-devel] [PATCH] q35: fix mmconfig and PCI0._CRS

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

On Wed, May 29, 2019 at 06:05:41PM -0400, Michael S. Tsirkin wrote:
> On Tue, May 28, 2019 at 10:43:31PM +0200, Gerd Hoffmann wrote:
> > This patch changes the handling of the mmconfig area.  Thanks to the
> > pci(e) expander devices we already have the logic to exclude address
> > ranges from PCI0._CRS.  We can simply add the mmconfig address range
> > to the list get it excluded as well.
> > 
> > With that in place we can go with a fixed pci hole which covers the
> > whole area from the end of (low) ram to the ioapic.
> > 
> > This will make the whole logic alot less fragile.  No matter where the
> > firmware places the mmconfig xbar, things should work correctly.  The
> > guest also gets a bit more PCI address space (seabios boot):
> > 
> >     # cat /proc/iomem
> >     [ ... ]
> >     7ffdd000-7fffffff : reserved
> >     80000000-afffffff : PCI Bus 0000:00            <<-- this is new
> >     b0000000-bfffffff : PCI MMCONFIG 0000 [bus 00-ff]
> >       b0000000-bfffffff : reserved
> >     c0000000-febfffff : PCI Bus 0000:00
> >       f8000000-fbffffff : 0000:00:01.0
> >     [ ... ]
> > 
> > So this is a guest visible change.
> > 
> > Cc: László Érsek <lersek@redhat.com>
> > Cc: Igor Mammedov <imammedo@redhat.com>
> > Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> 
> Hi Gerd!
> Please rebase on top of latest pci tree.
> 
> After the rebase this will start failing since we
> are now asserting on any changes to ACPI tables - and the way to
> fix it is to add a comma-separated list of
> changed ACPI tables to tests/bios-tables-test-allowed-diff.h
> 
> As a maintainer I will notice this and update the expected
> files before pushing.

ping.

> > ---
> >  hw/i386/acpi-build.c | 14 ++++++++++++++
> >  hw/pci-host/q35.c    | 31 ++++++++-----------------------
> >  2 files changed, 22 insertions(+), 23 deletions(-)
> > 
> > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > index 0d78d738948c..abb0e0ce9f27 100644
> > --- a/hw/i386/acpi-build.c
> > +++ b/hw/i386/acpi-build.c
> > @@ -122,6 +122,8 @@ typedef struct FwCfgTPMConfig {
> >      uint8_t tpmppi_version;
> >  } QEMU_PACKED FwCfgTPMConfig;
> >  
> > +static bool acpi_get_mcfg(AcpiMcfgInfo *mcfg);
> > +
> >  static void init_common_fadt_data(Object *o, AcpiFadtData *data)
> >  {
> >      uint32_t io = object_property_get_uint(o, ACPI_PM_PROP_PM_IO_BASE, NULL);
> > @@ -1807,6 +1809,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >      CrsRangeSet crs_range_set;
> >      PCMachineState *pcms = PC_MACHINE(machine);
> >      PCMachineClass *pcmc = PC_MACHINE_GET_CLASS(machine);
> > +    AcpiMcfgInfo mcfg;
> >      uint32_t nr_mem = machine->ram_slots;
> >      int root_bus_limit = 0xFF;
> >      PCIBus *bus = NULL;
> > @@ -1921,6 +1924,17 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
> >          }
> >      }
> >  
> > +    /*
> > +     * At this point crs_range_set has all the ranges used by pci
> > +     * busses *other* than PCI0.  These ranges will be excluded from
> > +     * the PCI0._CRS.  Add mmconfig to the set so it will be excluded
> > +     * too.
> > +     */
> > +    if (acpi_get_mcfg(&mcfg)) {
> > +        crs_range_insert(crs_range_set.mem_ranges,
> > +                         mcfg.base, mcfg.base + mcfg.size - 1);
> > +    }
> > +
> >      scope = aml_scope("\\_SB.PCI0");
> >      /* build PCI0._CRS */
> >      crs = aml_resource_template();
> > diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> > index 960939f5ed3e..72093320befe 100644
> > --- a/hw/pci-host/q35.c
> > +++ b/hw/pci-host/q35.c
> > @@ -258,15 +258,6 @@ static void q35_host_initfn(Object *obj)
> >      object_property_add_link(obj, MCH_HOST_PROP_IO_MEM, TYPE_MEMORY_REGION,
> >                               (Object **) &s->mch.address_space_io,
> >                               qdev_prop_allow_set_link_before_realize, 0, NULL);
> > -
> > -    /* Leave enough space for the biggest MCFG BAR */
> > -    /* TODO: this matches current bios behaviour, but
> > -     * it's not a power of two, which means an MTRR
> > -     * can't cover it exactly.
> > -     */
> > -    range_set_bounds(&s->mch.pci_hole,
> > -            MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT + MCH_HOST_BRIDGE_PCIEXBAR_MAX,
> > -            IO_APIC_DEFAULT_ADDRESS - 1);
> >  }
> >  
> >  static const TypeInfo q35_host_info = {
> > @@ -338,20 +329,6 @@ static void mch_update_pciexbar(MCHPCIState *mch)
> >      }
> >      addr = pciexbar & addr_mask;
> >      pcie_host_mmcfg_update(pehb, enable, addr, length);
> > -    /* Leave enough space for the MCFG BAR */
> > -    /*
> > -     * TODO: this matches current bios behaviour, but it's not a power of two,
> > -     * which means an MTRR can't cover it exactly.
> > -     */
> > -    if (enable) {
> > -        range_set_bounds(&mch->pci_hole,
> > -                         addr + length,
> > -                         IO_APIC_DEFAULT_ADDRESS - 1);
> > -    } else {
> > -        range_set_bounds(&mch->pci_hole,
> > -                         MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT,
> > -                         IO_APIC_DEFAULT_ADDRESS - 1);
> > -    }
> >  }
> >  
> >  /* PAM */
> > @@ -484,6 +461,14 @@ static void mch_update(MCHPCIState *mch)
> >      mch_update_pam(mch);
> >      mch_update_smram(mch);
> >      mch_update_ext_tseg_mbytes(mch);
> > +
> > +    /*
> > +     * pci hole goes from end-of-low-ram to io-apic.
> > +     * mmconfig will be excluded by the dsdt builder.
> > +     */
> > +    range_set_bounds(&mch->pci_hole,
> > +                     mch->below_4g_mem_size,
> > +                     IO_APIC_DEFAULT_ADDRESS - 1);
> >  }
> >  
> >  static int mch_post_load(void *opaque, int version_id)
> > -- 
> > 2.18.1