On 9/8/19 7:37 PM, Igor Druzhinin wrote: > On 09/09/2019 00:30, Boris Ostrovsky wrote: >> On 9/8/19 5:11 PM, Igor Druzhinin wrote: >>> On 08/09/2019 19:28, Boris Ostrovsky wrote: >>>> On 9/6/19 7:00 PM, Igor Druzhinin wrote: >>>>> On 06/09/2019 23:30, Boris Ostrovsky wrote: >>>>>> Where is MCFG parsed? pci_arch_init()? >>>>>>> It happens twice: >>>>> 1) first time early one in pci_arch_init() that is arch_initcall - that >>>>> time pci_mmcfg_list will be freed immediately there because MCFG area is >>>>> not reserved in E820; >>>>> 2) second time late one in acpi_init() which is subsystem_initcall right >>>>> before where PCI enumeration starts - this time ACPI tables will be >>>>> checked for a reserved resource and pci_mmcfg_list will be finally >>>>> populated. >>>>> >>>>> The problem is that on a system that doesn't have MCFG area reserved in >>>>> E820 pci_mmcfg_list is empty before acpi_init() and our PCI hooks are >>>>> called in the same place. So MCFG is still not in use by Xen at this >>>>> point since we haven't reached our xen_mcfg_late(). >>>> Would it be possible for us to parse MCFG ourselves in pci_xen_init()? I >>>> realize that we'd be doing this twice (or maybe even three times since >>>> apparently both pci_arch_init() and acpi_ini() do it). >>>> >>> I don't thine it makes sense: >>> a) it needs to be done after ACPI is initialized since we need to parse >>> it to figure out the exact reserved region - that's why it's currently >>> done in acpi_init() (see commit message for the reasons why) >> Hmm... We should be able to parse ACPI tables by the time >> pci_arch_init() is called. In fact, if you look at >> pci_mmcfg_early_init() you will see that it does just that. >> > The point is not to parse MCFG after acpi_init but to parse DSDT for > reserved resource which could be done only after ACPI initialization.
OK, I think I understand now what you are trying to do --- you are essentially trying to account for the range inserted by setup_mcfg_map(), right? The other question I have is why you think it's worth keeping xen_mcfg_late() as a late initcall. How could MCFG info be updated between acpi_init() and late_initcalls being run? I'd think it can only happen when a new device is hotplugged. -boris > >>> b) given (a) we cannot do it ourselves before acpi_init and after is too >>> late as we're already past ACPI PCI enumeration >>> c) we'd have to do it in the same place I call xen_mcfg_late() and it'd >>> be code duplication of what's already done by the existing code. >> >> If we manage to parse MCFG ourselves early then maybe we won't not need >> xen_mcfg_late()? We can call PHYSDEVOP_pci_mmcfg_reserved right away. > Again, this cannot be done untile acpi_init finishes basic setup to > parse DSDT. > > Igor _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
