On 26.02.2025 12:38, Jan Beulich wrote:
> Have callers invoke pci_add_segment() directly instead: With radix tree
> initialization moved out of the function, its name isn't quite
> describing anymore what it actually does.
>
> On x86 move the logic into __start_xen() itself, to reduce the risk of
> re-introducing ordering issues like the one which was addressed by
> 26fe09e34566 ("radix-tree: introduce RADIX_TREE{,_INIT}()").
>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
Arm maintainers: May I ask for an ack (or ...
> ---
> This is entirely optional and up for discussion. There certainly also is
> an argument towards keeping the function. Otoh on Arm there is the still
> open question whether segment 0 really is kind of special there (as it
> is on x86, largely for historical reasons), or whether the code can be
> dropped there altogether.
... otherwise) here please?
Jan
> ---
> v4: Move x86 logic into __start_xen() itself.
> v3: Adjust description to account for and re-base over dropped earlier
> patch.
> v2: New.
>
> --- a/xen/arch/arm/pci/pci.c
> +++ b/xen/arch/arm/pci/pci.c
> @@ -88,7 +88,8 @@ static int __init pci_init(void)
> if ( !pci_passthrough_enabled )
> return 0;
>
> - pci_segments_init();
> + if ( pci_add_segment(0) )
> + panic("Could not initialize PCI segment 0\n");
>
> if ( acpi_disabled )
> return dt_pci_init();
> --- a/xen/arch/x86/x86_64/mmconfig-shared.c
> +++ b/xen/arch/x86/x86_64/mmconfig-shared.c
> @@ -402,8 +402,6 @@ void __init acpi_mmcfg_init(void)
> {
> bool valid = true;
>
> - pci_segments_init();
> -
> /* MMCONFIG disabled */
> if ((pci_probe & PCI_PROBE_MMCONF) == 0)
> return;
> --- a/xen/arch/x86/setup.c
> +++ b/xen/arch/x86/setup.c
> @@ -1898,6 +1898,13 @@ void asmlinkage __init noreturn __start_
> setup_system_domains();
>
> /*
> + * Ahead of any ACPI table parsing make sure we have control structures
> + * for PCI segment 0.
> + */
> + if ( pci_add_segment(0) )
> + panic("Could not initialize PCI segment 0\n");
> +
> + /*
> * IOMMU-related ACPI table parsing has to happen before APIC probing,
> for
> * check_x2apic_preenabled() to be able to observe respective findings,
> in
> * particular iommu_intremap having got turned off.
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -127,12 +127,6 @@ static int pci_segments_iterate(
> return rc;
> }
>
> -void __init pci_segments_init(void)
> -{
> - if ( !alloc_pseg(0) )
> - panic("Could not initialize PCI segment 0\n");
> -}
> -
> int __init pci_add_segment(u16 seg)
> {
> return alloc_pseg(seg) ? 0 : -ENOMEM;
> --- a/xen/include/xen/pci.h
> +++ b/xen/include/xen/pci.h
> @@ -219,7 +219,6 @@ void setup_hwdom_pci_devices(struct doma
> int (*handler)(uint8_t devfn,
> struct pci_dev *pdev));
> int pci_release_devices(struct domain *d);
> -void pci_segments_init(void);
> int pci_add_segment(u16 seg);
> const unsigned long *pci_get_ro_map(u16 seg);
> int pci_add_device(u16 seg, u8 bus, u8 devfn,
