linux-kernel - [tip:x86/apic] x86, irq: Prefer assigned ID in APIC ID register for x86

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <tip-5411dc4ccb25de133701774dd2a3cf3f7e246f17@git.kernel.org>
Date:	Fri, 19 Dec 2014 06:03:28 -0800
From:	tip-bot for Yinghai Lu <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	hpa@...or.com, yinghai@...nel.org, bhelgaas@...gle.com,
	tglx@...utronix.de, konrad.wilk@...cle.com,
	gregkh@...uxfoundation.org, bp@...en8.de, joro@...tes.org,
	rjw@...ysocki.net, sebastian@...akpoint.cc, rdunlap@...radead.org,
	mingo@...nel.org, linux-kernel@...r.kernel.org,
	benh@...nel.crashing.org, prarit@...hat.com,
	grant.likely@...aro.org, jiang.liu@...ux.intel.com,
	tony.luck@...el.com
Subject: [tip:x86/apic] x86, irq:
  Prefer assigned ID in APIC ID register for x86_64

Commit-ID:  5411dc4ccb25de133701774dd2a3cf3f7e246f17
Gitweb:     http://git.kernel.org/tip/5411dc4ccb25de133701774dd2a3cf3f7e246f17
Author:     Yinghai Lu <yinghai@...nel.org>
AuthorDate: Mon, 27 Oct 2014 13:21:40 +0800
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Tue, 16 Dec 2014 14:08:15 +0100

x86, irq: Prefer assigned ID in APIC ID register for x86_64

Perfer the assigned ID in APIC ID register for x86_64 if it's still
available.

[ tglx: Added comments ]

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Signed-off-by: Jiang Liu <jiang.liu@...ux.intel.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc: Tony Luck <tony.luck@...el.com>
Cc: Joerg Roedel <joro@...tes.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Sebastian Andrzej Siewior <sebastian@...akpoint.cc>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Cc: Rafael J. Wysocki <rjw@...ysocki.net>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Randy Dunlap <rdunlap@...radead.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Grant Likely <grant.likely@...aro.org>
Cc: Prarit Bhargava <prarit@...hat.com>
Link: http://lkml.kernel.org/r/1414387308-27148-11-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

---
 arch/x86/kernel/apic/io_apic.c | 45 ++++++++++++++++++++++++++++++++++++------
 1 file changed, 39 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 654b69b..86fd286 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3580,26 +3580,59 @@ static int __init io_apic_get_unique_id(int ioapic, int apic_id)
 	return apic_id;
 }
 
-static u8 __init io_apic_unique_id(u8 id)
+static u8 __init io_apic_unique_id(int idx, u8 id)
 {
 	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
 	    !APIC_XAPIC(apic_version[boot_cpu_physical_apicid]))
-		return io_apic_get_unique_id(nr_ioapics, id);
+		return io_apic_get_unique_id(idx, id);
 	else
 		return id;
 }
 #else
-static u8 __init io_apic_unique_id(u8 id)
+static u8 __init io_apic_unique_id(int idx, u8 id)
 {
-	int i;
+	union IO_APIC_reg_00 reg_00;
 	DECLARE_BITMAP(used, 256);
+	unsigned long flags;
+	u8 new_id;
+	int i;
 
 	bitmap_zero(used, 256);
 	for_each_ioapic(i)
 		__set_bit(mpc_ioapic_id(i), used);
+
+	/* Hand out the requested id if available */
 	if (!test_bit(id, used))
 		return id;
-	return find_first_zero_bit(used, 256);
+
+	/*
+	 * Read the current id from the ioapic and keep it if
+	 * available.
+	 */
+	raw_spin_lock_irqsave(&ioapic_lock, flags);
+	reg_00.raw = io_apic_read(idx, 0);
+	raw_spin_unlock_irqrestore(&ioapic_lock, flags);
+	new_id = reg_00.bits.ID;
+	if (!test_bit(new_id, used)) {
+		apic_printk(APIC_VERBOSE, KERN_INFO
+			"IOAPIC[%d]: Using reg apic_id %d instead of %d\n",
+			 idx, new_id, id);
+		return new_id;
+	}
+
+	/*
+	 * Get the next free id and write it to the ioapic.
+	 */
+	new_id = find_first_zero_bit(used, 256);
+	reg_00.bits.ID = new_id;
+	raw_spin_lock_irqsave(&ioapic_lock, flags);
+	io_apic_write(idx, 0, reg_00.raw);
+	reg_00.raw = io_apic_read(idx, 0);
+	raw_spin_unlock_irqrestore(&ioapic_lock, flags);
+	/* Sanity check */
+	BUG_ON(reg_00.bits.ID != new_id);
+
+	return new_id;
 }
 #endif
 
@@ -3865,7 +3898,7 @@ void __init mp_register_ioapic(int id, u32 address, u32 gsi_base,
 		return;
 	}
 
-	ioapics[idx].mp_config.apicid = io_apic_unique_id(id);
+	ioapics[idx].mp_config.apicid = io_apic_unique_id(idx, id);
 	ioapics[idx].mp_config.apicver = io_apic_get_version(idx);
 
 	/*
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/