git: 0ef872c9353e - stable/14 - io_apic: Support APIC Extended Destination IDs

The branch stable/14 has been updated by cperciva:

URL: https://cgit.FreeBSD.org/src/commit/?id=0ef872c9353e83bfbfe4cba15a1960fa391cb5a4

commit 0ef872c9353e83bfbfe4cba15a1960fa391cb5a4
Author:     Colin Percival <cperciva@FreeBSD.org>
AuthorDate: 2026-03-16 23:45:32 +0000
Commit:     Colin Percival <cperciva@FreeBSD.org>
CommitDate: 2026-04-16 15:11:54 +0000

    io_apic: Support APIC Extended Destination IDs
    
    If APIC Extended Destination ID support is enabled, use it in APIC RTEs
    by allowing APIC IDs up to 2^15 - 1 and encoding the high bits into
    Intel "reserved" bits per the standard.
    
    Reviewed by:    kib
    MFC after:      3 weeks
    Sponsored by:   Amazon
    Differential Revision:  https://reviews.freebsd.org/D55889
    
    (cherry picked from commit b0e1b1069d655f12ab69cf3a1dc1904dd35ad1da)
---
 sys/x86/include/apicvar.h | 1 +
 sys/x86/x86/io_apic.c     | 7 +++++++
 2 files changed, 8 insertions(+)

diff --git a/sys/x86/include/apicvar.h b/sys/x86/include/apicvar.h
index bb2986c3bf67..36ce48339ad4 100644
--- a/sys/x86/include/apicvar.h
+++ b/sys/x86/include/apicvar.h
@@ -84,6 +84,7 @@
  * to use that ID.
  */
 #define	IOAPIC_MAX_ID		0xff
+#define	IOAPIC_MAX_EXT_ID	0x7fff
 
 /* I/O Interrupts are used for external devices such as ISA, PCI, etc. */
 #define	APIC_IO_INTS	(IDT_IO_INTS + 16)
diff --git a/sys/x86/x86/io_apic.c b/sys/x86/x86/io_apic.c
index ae104beadf6a..56acd091c205 100644
--- a/sys/x86/x86/io_apic.c
+++ b/sys/x86/x86/io_apic.c
@@ -371,6 +371,13 @@ ioapic_program_intpin(struct ioapic_intsrc *intpin)
 		low = IOART_DESTPHY;
 		high = intpin->io_cpu << APIC_ID_SHIFT;
 		intpin->io_valid = 1;
+	} else if (intpin->io_cpu <= IOAPIC_MAX_EXT_ID &&
+	    apic_ext_dest_id == 1) {
+		low = IOART_DESTPHY;
+		high = intpin->io_cpu << APIC_ID_SHIFT & APIC_ID_MASK;
+		high |= (intpin->io_cpu >> 8) << APIC_EXT_ID_SHIFT
+		    & APIC_EXT_ID_MASK;
+		intpin->io_valid = 1;
 	} else {
 		printf("%s: unsupported destination APIC ID %u for pin %u\n",
 		    __func__, intpin->io_cpu, intpin->io_intpin);