Re: [PATCH 2/2] x86/acpi: Remove the repeated lapic address override entry parsing

From: Rafael J. Wysocki
Date: Mon Jun 27 2016 - 21:21:35 EST


On Tuesday, June 28, 2016 07:41:36 AM Baoquan He wrote:
> ACPI MADT has a 32-bit field providing lapic address at which
> each processor can access its lapic information. MADT also contains
> an optional entry to provide a 64-bit address to override the 32-bit
> one. However the current code does the lapic address override entry
> parsing twice. One is in early_acpi_boot_init() because AMD NUMA need
> get boot_cpu_id earlier. The other is in acpi_boot_init() which parses
> all MADT entries. The relevant log will be printed out twice too and
> this may confuse people.
>
> So in this patch remove the repeated code in the 2nd part. Meanwhile
> add code comment above early_acpi_boot_init() to explain why its
> calling need be earlier, and print lapic override inforamtion like
> other MADT entry.
>
> Signed-off-by: Baoquan He <bhe@xxxxxxxxxx>
> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
> Cc: Len Brown <len.brown@xxxxxxxxx>
> Cc: Pavel Machek <pavel@xxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxx>
> Cc: Shaohua Li <shli@xxxxxx>
> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> Cc: Hidehiro Kawai <hidehiro.kawai.ez@xxxxxxxxxxx>
> Cc: Juergen Gross <jgross@xxxxxxxx>
> Cc: Joerg Roedel <jroedel@xxxxxxx>
> Cc: Dave Young <dyoung@xxxxxxxxxx>
> Cc: Lv Zheng <lv.zheng@xxxxxxxxx>
> Cc: Toshi Kani <toshi.kani@xxxxxxx>
> Cc: Mark Salter <msalter@xxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> ---
> arch/x86/kernel/acpi/boot.c | 17 ++---------------
> arch/x86/kernel/apic/apic.c | 2 +-
> arch/x86/kernel/setup.c | 3 +++
> 3 files changed, 6 insertions(+), 16 deletions(-)
>
> diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
> index 9414f84..6ef3694 100644
> --- a/arch/x86/kernel/acpi/boot.c
> +++ b/arch/x86/kernel/acpi/boot.c
> @@ -274,6 +274,8 @@ acpi_parse_lapic_addr_ovr(struct acpi_subtable_header * header,
> if (BAD_MADT_ENTRY(lapic_addr_ovr, end))
> return -EINVAL;
>
> + acpi_table_print_madt_entry(header);
> +
> acpi_lapic_addr = lapic_addr_ovr->address;
>
> return 0;
> @@ -990,21 +992,6 @@ static int __init acpi_parse_madt_lapic_entries(void)
> if (!boot_cpu_has(X86_FEATURE_APIC))
> return -ENODEV;
>
> - /*
> - * Note that the LAPIC address is obtained from the MADT (32-bit value)
> - * and (optionally) overridden by a LAPIC_ADDR_OVR entry (64-bit value).
> - */
> -
> - count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_APIC_OVERRIDE,
> - acpi_parse_lapic_addr_ovr, 0);
> - if (count < 0) {
> - printk(KERN_ERR PREFIX
> - "Error parsing LAPIC address override entry\n");
> - return count;
> - }
> -
> - register_lapic_address(acpi_lapic_addr);
> -

I'm not really sure if this change is correct.

Does it only deal with the override?

> count = acpi_table_parse_madt(ACPI_MADT_TYPE_LOCAL_SAPIC,
> acpi_parse_sapic, MAX_LOCAL_APIC);
>
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index 60078a6..504311c 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -1799,7 +1799,7 @@ void __init register_lapic_address(unsigned long address)
> if (!x2apic_mode) {
> set_fixmap_nocache(FIX_APIC_BASE, address);
> apic_printk(APIC_VERBOSE, "mapped APIC to %16lx (%16lx)\n",
> - APIC_BASE, mp_lapic_addr);
> + APIC_BASE, address);
> }
> if (boot_cpu_physical_apicid == -1U) {
> boot_cpu_physical_apicid = read_apic_id();
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index c4e7b39..059680d 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1157,6 +1157,9 @@ void __init setup_arch(char **cmdline_p)
> */
> acpi_boot_table_init();
>
> + /*
> + * AMD NUMA support need get boot_cpu_id earlier.
> + */

Surely that's not the only goal of early_acpi_boot_init(), is it?

> early_acpi_boot_init();
>
> initmem_init();
>

Please CC ACPI-related patches to linux-acpi@xxxxxxxxxxxxxxxx

Thanks,
Rafael