<gregkh@xxxxxxxxxxxxxxxxxxx> writes: > This is a note to let you know that I've just added the patch titled > > x86/irq: Probe for PIC presence before allocating descs for legacy IRQs > > to the 4.3-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > x86-irq-probe-for-pic-presence-before-allocating-descs-for-legacy-irqs.patch > and it can be found in the queue-4.3 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. This commit is known for breaking Xen PV guests, the breakage is fixed with the following: commit b4ff8389ed14b849354b59ce9b360bdefcdbf99c Author: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Date: Fri Nov 20 11:25:04 2015 -0500 xen/events: Always allocate legacy interrupts on PV guests I suggest we include this commit as well. Same for 4.2-stable tree. > > From 8c058b0b9c34d8c8d7912880956543769323e2d8 Mon Sep 17 00:00:00 2001 > From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > Date: Tue, 3 Nov 2015 10:40:14 +0100 > Subject: x86/irq: Probe for PIC presence before allocating descs for legacy IRQs > > From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> > > commit 8c058b0b9c34d8c8d7912880956543769323e2d8 upstream. > > 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 <vkuznets@xxxxxxxxxx> > Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx> > Cc: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > Link: http://lkml.kernel.org/r/1446543614-3621-1-git-send-email-vkuznets@xxxxxxxxxx > Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > --- > 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(-) > > --- 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); > }; > --- 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 > --- 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(u > { > 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, > }; > > Patches currently in stable-queue which might be from vkuznets@xxxxxxxxxx are > > queue-4.3/x86-irq-probe-for-pic-presence-before-allocating-descs-for-legacy-irqs.patch -- Vitaly -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html