linux-kernel - [patch V3 05/22] x86/ioapic: Make io_apic_get_unique

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Date: Tue, 13 Feb 2024 22:04:57 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org,
 Tom Lendacky <thomas.lendacky@....com>,
 Andrew Cooper <andrew.cooper3@...rix.com>,
 Arjan van de Ven <arjan@...ux.intel.com>,
 Huang Rui <ray.huang@....com>,
 Juergen Gross <jgross@...e.com>,
 Dimitri Sivanich <dimitri.sivanich@....com>,
 Sohil Mehta <sohil.mehta@...el.com>,
 K Prateek Nayak <kprateek.nayak@....com>,
 Kan Liang <kan.liang@...ux.intel.com>,
 Zhang Rui <rui.zhang@...el.com>,
 "Paul E. McKenney" <paulmck@...nel.org>,
 Feng Tang <feng.tang@...el.com>,
 Andy Shevchenko <andy@...radead.org>,
 Michael Kelley <mhklinux@...look.com>,
 "Peter Zijlstra (Intel)" <peterz@...radead.org>,
 Andy Shevchenko <andy.shevchenko@...il.com>,
 Wei Liu <wei.liu@...nel.org>
Subject: [patch V3 05/22] x86/ioapic: Make io_apic_get_unique_id() simpler

From: Thomas Gleixner <tglx@...utronix.de>

No need to go through APIC callbacks. It's already established that this is
an ancient APIC. So just copy the present mask and use the direct physid*
functions all over the place.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/apic/io_apic.c |   22 +++++-----------------
 1 file changed, 5 insertions(+), 17 deletions(-)
---

--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -2498,17 +2498,9 @@ static int io_apic_get_unique_id(int ioa
 	unsigned long flags;
 	int i = 0;

-	/*
-	 * The P4 platform supports up to 256 APIC IDs on two separate APIC
-	 * buses (one for LAPICs, one for IOAPICs), where predecessors only
-	 * supports up to 16 on one shared APIC bus.
-	 *
-	 * TBD: Expand LAPIC/IOAPIC support on P4-class systems to take full
-	 *      advantage of new APIC bus architecture.
-	 */
-
+	/* Initialize the ID map */
 	if (physids_empty(apic_id_map))
-		apic->ioapic_phys_id_map(&phys_cpu_present_map, &apic_id_map);
+		apic_id_map = phys_cpu_present_map;

 	raw_spin_lock_irqsave(&ioapic_lock, flags);
 	reg_00.raw = io_apic_read(ioapic, 0);
@@ -2520,14 +2512,10 @@ static int io_apic_get_unique_id(int ioa
 		apic_id = reg_00.bits.ID;
 	}

-	/*
-	 * Every APIC in a system must have a unique ID or we get lots of nice
-	 * 'stuck on smp_invalidate_needed IPI wait' messages.
-	 */
-	if (apic->check_apicid_used(&apic_id_map, apic_id)) {
-
+	/* Every APIC in a system must have a unique ID */
+	if (physid_isset(apic_id, apic_id_map)) {
 		for (i = 0; i < broadcast_id; i++) {
-			if (!apic->check_apicid_used(&apic_id_map, i))
+			if (!physid_isset(i, apic_id_map))
 				break;
 		}