Merge tag 'x86-boot-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86/boot updates from Ingo Molnar:

 - x86/acpi: Add acpi=spcr to use SPCR-provided default console
   (Shenghao Yang)

 - x86/acpi/boot: Correct the acpi_is_processor_usable() check again
   (Yazen Ghannam)

 - Refresh the x86 memory map (e820 table) handling code, and make the
   printouts a bit more informative (Ingo Molnar)

* tag 'x86-boot-2026-02-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  x86/acpi: Add acpi=spcr to use SPCR-provided default console
  x86/boot/e820: Use <linux/sizes.h> symbols for literals
  x86/boot/e820: Make sure e820_search_gap() finds all gaps
  x86/boot/e820: Simplify the e820__range_remove() API
  x86/boot/e820: Remove e820__range_remove()'s unused return parameter
  x86/boot/e820: Simplify append_e820_table() and remove restriction on single-entry tables
  x86/boot/e820: Standardize __init/__initdata tag placement
  x86/boot/e820: Simplify & clarify __e820__range_add() a bit
  x86/boot/e820: Rename gap_start/gap_size to max_gap_start/max_gap_start in e820_search_gap() et al
  x86/boot/e820: Change e820_search_gap() to search for the highest-address PCI gap
  x86/boot/e820: Clean up e820__setup_pci_gap()/e820_search_gap() a bit
  x86/boot/e820: Change struct e820_table::nr_entries type from __u32 to u32
  x86/boot/e820: Standardize e820 table index variable types under 'u32'
  x86/boot/e820: Standardize e820 table index variable names under 'idx'
  x86/boot/e820: Remove unnecessary header inclusions
  x86/boot/e820: Clean up __refdata use a bit
  x86/boot/e820: Clean up __e820__range_add() a bit
  x86/boot/e820: Improve e820_print_type() messages
  x86/boot/e820: Clean up confusing and self-contradictory verbiage around E820 related resource allocations
  x86/boot/e820: Remove pointless early_panic() indirection
  ...

Author: torvalds

Documentation/admin-guide/kernel-parameters.txt

@@ -125,6 +125,8 @@ Kernel parameters
 			may result in duplicate corrected error reports.
 			nospcr -- disable console in ACPI SPCR table as
 				default _serial_ console on ARM64
+			spcr -- enable console in ACPI SPCR table as
+				default _serial_ console on x86
 			For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
 			"acpi=nospcr" are available
 			For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"

arch/x86/include/asm/e820/api.h

@@ -16,10 +16,9 @@ extern bool e820__mapped_all(u64 start, u64 end, enum e820_type type);
 
 extern void e820__range_add   (u64 start, u64 size, enum e820_type type);
 extern u64  e820__range_update(u64 start, u64 size, enum e820_type old_type, enum e820_type new_type);
-extern u64  e820__range_remove(u64 start, u64 size, enum e820_type old_type, bool check_type);
+extern void e820__range_remove(u64 start, u64 size, enum e820_type filter_type);
 extern u64  e820__range_update_table(struct e820_table *t, u64 start, u64 size, enum e820_type old_type, enum e820_type new_type);
 
-extern void e820__print_table(char *who);
 extern int  e820__update_table(struct e820_table *table);
 extern void e820__update_table_print(void);
 

arch/x86/include/asm/e820/types.h

@@ -83,7 +83,7 @@ struct e820_entry {
  * The whole array of E820 entries:
  */
 struct e820_table {
-	__u32 nr_entries;
+	u32 nr_entries;
 	struct e820_entry entries[E820_MAX_ENTRIES];
 };
 

arch/x86/kernel/acpi/boot.c

@@ -35,6 +35,7 @@
 #include <asm/smp.h>
 #include <asm/i8259.h>
 #include <asm/setup.h>
+#include <asm/hypervisor.h>
 
 #include "sleep.h" /* To include x86_acpi_suspend_lowlevel */
 static int __initdata acpi_force = 0;
@@ -47,7 +48,8 @@ EXPORT_SYMBOL(acpi_disabled);
 
 int acpi_noirq;				/* skip ACPI IRQ initialization */
 static int acpi_nobgrt;			/* skip ACPI BGRT */
-int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
+static int acpi_spcr_add __initdata;	/* add SPCR-provided console */
+int acpi_pci_disabled;			/* skip ACPI PCI scan and IRQ initialization */
 EXPORT_SYMBOL(acpi_pci_disabled);
 
 int acpi_lapic;
@@ -164,11 +166,14 @@ static bool __init acpi_is_processor_usable(u32 lapic_flags)
 	if (lapic_flags & ACPI_MADT_ENABLED)
 		return true;
 
-	if (!acpi_support_online_capable ||
-	    (lapic_flags & ACPI_MADT_ONLINE_CAPABLE))
-		return true;
+	if (acpi_support_online_capable)
+		return lapic_flags & ACPI_MADT_ONLINE_CAPABLE;
 
-	return false;
+	/*
+	 * QEMU expects legacy "Enabled=0" LAPIC entries to be counted as usable
+	 * in order to support CPU hotplug in guests.
+	 */
+	return !hypervisor_is_type(X86_HYPER_NATIVE);
 }
 
 static int __init
@@ -1665,8 +1670,8 @@ int __init acpi_boot_init(void)
 	if (!acpi_noirq)
 		x86_init.pci.init = pci_acpi_init;
 
-	/* Do not enable ACPI SPCR console by default */
-	acpi_parse_spcr(earlycon_acpi_spcr_enable, false);
+	acpi_parse_spcr(earlycon_acpi_spcr_enable, acpi_spcr_add);
+
 	return 0;
 }
 
@@ -1703,6 +1708,10 @@ static int __init parse_acpi(char *arg)
 	/* "acpi=nocmcff" disables FF mode for corrected errors */
 	else if (strcmp(arg, "nocmcff") == 0) {
 		acpi_disable_cmcff = 1;
+	}
+	/* "acpi=spcr" adds the SPCR-provided console as a preferred one */
+	else if (strcmp(arg, "spcr") == 0) {
+		acpi_spcr_add = 1;
 	} else {
 		/* Core will printk when we return error. */
 		return -EINVAL;

arch/x86/kernel/cpu/topology.c

@@ -27,7 +27,6 @@
 #include <xen/xen.h>
 
 #include <asm/apic.h>
-#include <asm/hypervisor.h>
 #include <asm/io_apic.h>
 #include <asm/mpspec.h>
 #include <asm/msr.h>
@@ -236,20 +235,6 @@ static __init void topo_register_apic(u32 apic_id, u32 acpi_id, bool present)
 		cpuid_to_apicid[cpu] = apic_id;
 		topo_set_cpuids(cpu, apic_id, acpi_id);
 	} else {
-		u32 pkgid = topo_apicid(apic_id, TOPO_PKG_DOMAIN);
-
-		/*
-		 * Check for present APICs in the same package when running
-		 * on bare metal. Allow the bogosity in a guest.
-		 */
-		if (hypervisor_is_type(X86_HYPER_NATIVE) &&
-		    topo_unit_count(pkgid, TOPO_PKG_DOMAIN, phys_cpu_present_map)) {
-			pr_info_once("Ignoring hot-pluggable APIC ID %x in present package.\n",
-				     apic_id);
-			topo_info.nr_rejected_cpus++;
-			return;
-		}
-
 		topo_info.nr_disabled_cpus++;
 	}