[xen master] x86/ACPI: ignore processors which cannot be brought online

[patchbot@xxxxxxx]

commit 0a7ebb1861062f795bab53272789ed2802d84ec0
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Sep 15 11:00:40 2021 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Sep 15 11:00:40 2021 +0200

    x86/ACPI: ignore processors which cannot be brought online
    
    ACPI 6.3 introduced a flag allowing to tell MADT entries describing
    hotpluggable processors from ones which are simply placeholders (often
    used by firmware writers to simplify handling there).
    
    Inspired by a Linux patch by Mario Limonciello <mario.limonciello@xxxxxxx>.
    
    Requested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/acpi/boot.c  | 16 ++++++++++++++++
 xen/include/acpi/actbl1.h |  3 ++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/acpi/boot.c b/xen/arch/x86/acpi/boot.c
index 8fe2d6fe0f..5e38b4b17c 100644
--- a/xen/arch/x86/acpi/boot.c
+++ b/xen/arch/x86/acpi/boot.c
@@ -53,6 +53,8 @@ bool __initdata acpi_ioapic;
 static bool __initdata acpi_skip_timer_override;
 boolean_param("acpi_skip_timer_override", acpi_skip_timer_override);
 
+static uint8_t __initdata madt_revision;
+
 static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE;
 
 /* --------------------------------------------------------------------------
@@ -64,6 +66,8 @@ static int __init acpi_parse_madt(struct acpi_table_header 
*table)
        struct acpi_table_madt *madt =
                container_of(table, struct acpi_table_madt, header);
 
+       madt_revision = madt->header.revision;
+
        if (madt->address) {
                acpi_lapic_addr = (u64) madt->address;
 
@@ -86,6 +90,12 @@ acpi_parse_x2apic(struct acpi_subtable_header *header, const 
unsigned long end)
        if (BAD_MADT_ENTRY(processor, end))
                return -EINVAL;
 
+       /* Don't register processors that cannot be onlined. */
+       if (madt_revision >= 5 &&
+           !(processor->lapic_flags & ACPI_MADT_ENABLED) &&
+           !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
+               return 0;
+
        if ((processor->lapic_flags & ACPI_MADT_ENABLED) ||
            processor->local_apic_id != 0xffffffff || opt_cpu_info) {
                acpi_table_print_madt_entry(header);
@@ -136,6 +146,12 @@ acpi_parse_lapic(struct acpi_subtable_header * header, 
const unsigned long end)
        if (BAD_MADT_ENTRY(processor, end))
                return -EINVAL;
 
+       /* Don't register processors that cannot be onlined. */
+       if (madt_revision >= 5 &&
+           !(processor->lapic_flags & ACPI_MADT_ENABLED) &&
+           !(processor->lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
+               return 0;
+
        if ((processor->lapic_flags & ACPI_MADT_ENABLED) ||
            processor->id != 0xff || opt_cpu_info)
                acpi_table_print_madt_entry(header);
diff --git a/xen/include/acpi/actbl1.h b/xen/include/acpi/actbl1.h
index e1991362dc..923641fc9e 100644
--- a/xen/include/acpi/actbl1.h
+++ b/xen/include/acpi/actbl1.h
@@ -858,7 +858,8 @@ struct acpi_madt_generic_translator {
 
 /* MADT Local APIC flags */
 
-#define ACPI_MADT_ENABLED           (1)        /* 00: Processor is usable if 
set */
+#define ACPI_MADT_ENABLED           (1 << 0)   /* 00: Processor is usable if 
set */
+#define ACPI_MADT_ONLINE_CAPABLE    (1 << 1)   /* 01: Processor can be onlined 
*/
 
 /* MADT MPS INTI flags (inti_flags) */
 
--
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