Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752768AbbKCJkX (ORCPT ); Tue, 3 Nov 2015 04:40:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54834 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751016AbbKCJkT (ORCPT ); Tue, 3 Nov 2015 04:40:19 -0500 From: Vitaly Kuznetsov To: x86@kernel.org Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Jiang Liu , "K. Y. Srinivasan" , linux-kernel@vger.kernel.org Subject: [PATCH v2] x86/irq: Probe for PIC presence before allocating descs for legacy IRQs Date: Tue, 3 Nov 2015 10:40:14 +0100 Message-Id: <1446543614-3621-1-git-send-email-vkuznets@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4900 Lines: 149 Commit d32932d02e18 ("x86/irq: Convert IOAPIC to use hierarchical irqdomain interfaces") brought a regression for Hyper-V Gen2 instances. These instances don't have i8259 legacy PIC but they use legacy IRQs for serial port, rtc, and acpi. With this commit included we end up with these IRQs not initialized. Earlier, there was a special workaround for legacy IRQs in mp_map_pin_to_irq() doing mp_irqdomain_map() without looking at nr_legacy_irqs() and now we fail in __irq_domain_alloc_irqs() when irq_domain_alloc_descs() returns -EEXIST. The essence of the issue seems to be that early_irq_init() calls arch_probe_nr_irqs() to figure out the number of legacy IRQs before we probe for i8259 and gets 16. Later when init_8259A() is called we switch to NULL legacy PIC and nr_legacy_irqs() starts to return 0 but we already have 16 descs allocated. Solve the issue by separating i8259 probe from init and calling it in arch_probe_nr_irqs() before we actually use nr_legacy_irqs() information. Fixes: d32932d02e18 ("x86/irq: Convert IOAPIC to use hierarchical irqdomain interfaces") Signed-off-by: Vitaly Kuznetsov --- Changes since v1: - Make probe() return the number of legacy irqs [Thomas Gleixner]. I'm not particularly sure it's gonna be obvious for future readers to realize that probe() is not just a binary answer to the question if PIC is present but introducing other entities here looks like an overkill. --- arch/x86/include/asm/i8259.h | 1 + arch/x86/kernel/apic/vector.c | 6 +++++- arch/x86/kernel/i8259.c | 29 +++++++++++++++++++++-------- 3 files changed, 27 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/i8259.h b/arch/x86/include/asm/i8259.h index ccffa53..39bcefc 100644 --- a/arch/x86/include/asm/i8259.h +++ b/arch/x86/include/asm/i8259.h @@ -60,6 +60,7 @@ struct legacy_pic { void (*mask_all)(void); void (*restore_mask)(void); void (*init)(int auto_eoi); + int (*probe)(void); int (*irq_pending)(unsigned int irq); void (*make_irq)(unsigned int irq); }; diff --git a/arch/x86/kernel/apic/vector.c b/arch/x86/kernel/apic/vector.c index 836d11b..861bc59 100644 --- a/arch/x86/kernel/apic/vector.c +++ b/arch/x86/kernel/apic/vector.c @@ -361,7 +361,11 @@ int __init arch_probe_nr_irqs(void) if (nr < nr_irqs) nr_irqs = nr; - return nr_legacy_irqs(); + /* + * We don't know if PIC is present at this point so we need to do + * probe() to get the right number of legacy IRQs. + */ + return legacy_pic->probe(); } #ifdef CONFIG_X86_IO_APIC diff --git a/arch/x86/kernel/i8259.c b/arch/x86/kernel/i8259.c index 16cb827..be22f5a 100644 --- a/arch/x86/kernel/i8259.c +++ b/arch/x86/kernel/i8259.c @@ -295,16 +295,11 @@ static void unmask_8259A(void) raw_spin_unlock_irqrestore(&i8259A_lock, flags); } -static void init_8259A(int auto_eoi) +static int probe_8259A(void) { unsigned long flags; unsigned char probe_val = ~(1 << PIC_CASCADE_IR); unsigned char new_val; - - i8259A_auto_eoi = auto_eoi; - - raw_spin_lock_irqsave(&i8259A_lock, flags); - /* * Check to see if we have a PIC. * Mask all except the cascade and read @@ -312,16 +307,28 @@ static void init_8259A(int auto_eoi) * have a PIC, we will read 0xff as opposed to the * value we wrote. */ + raw_spin_lock_irqsave(&i8259A_lock, flags); + outb(0xff, PIC_SLAVE_IMR); /* mask all of 8259A-2 */ outb(probe_val, PIC_MASTER_IMR); new_val = inb(PIC_MASTER_IMR); if (new_val != probe_val) { printk(KERN_INFO "Using NULL legacy PIC\n"); legacy_pic = &null_legacy_pic; - raw_spin_unlock_irqrestore(&i8259A_lock, flags); - return; } + raw_spin_unlock_irqrestore(&i8259A_lock, flags); + return nr_legacy_irqs(); +} + +static void init_8259A(int auto_eoi) +{ + unsigned long flags; + + i8259A_auto_eoi = auto_eoi; + + raw_spin_lock_irqsave(&i8259A_lock, flags); + outb(0xff, PIC_MASTER_IMR); /* mask all of 8259A-1 */ /* @@ -379,6 +386,10 @@ static int legacy_pic_irq_pending_noop(unsigned int irq) { return 0; } +static int legacy_pic_probe(void) +{ + return 0; +} struct legacy_pic null_legacy_pic = { .nr_legacy_irqs = 0, @@ -388,6 +399,7 @@ struct legacy_pic null_legacy_pic = { .mask_all = legacy_pic_noop, .restore_mask = legacy_pic_noop, .init = legacy_pic_int_noop, + .probe = legacy_pic_probe, .irq_pending = legacy_pic_irq_pending_noop, .make_irq = legacy_pic_uint_noop, }; @@ -400,6 +412,7 @@ struct legacy_pic default_legacy_pic = { .mask_all = mask_8259A, .restore_mask = unmask_8259A, .init = init_8259A, + .probe = probe_8259A, .irq_pending = i8259A_irq_pending, .make_irq = make_8259A_irq, }; -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/