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Commit be5d5350 authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar
Browse files

x86: MSI start irq numbering from nr_irqs_gsi 



Impact: sanitize MSI irq number ordering from top-down to bottom-up

Increase new MSI IRQs starting from nr_irqs_gsi (which is somewhere below
256), instead of decreasing from NR_IRQS. (The latter method can result
in confusingly high IRQ numbers - if NR_CPUS is set to a high value and
NR_IRQS scales up to a high value.)

Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 99d093d1

arch/x86/include/asm/io_apic.h

+1 −1
Original line number Diff line number Diff line
@@ -188,7 +188,7 @@ extern void restore_IO_APIC_setup(void); 
extern void reinit_intr_remapped_IO_APIC(int);

#endif



extern int probe_nr_irqs(void);

extern void probe_nr_irqs_gsi(void);



#else  /* !CONFIG_X86_IO_APIC */

#define io_apic_assign_pci_irqs 0

arch/x86/kernel/io_apic.c

+17 −7
Original line number Diff line number Diff line
@@ -2973,7 +2973,7 @@ unsigned int create_irq_nr(unsigned int irq_want) 


	irq = 0;

	spin_lock_irqsave(&vector_lock, flags);

	for (new = irq_want; new > 0; new--) {

	for (new = irq_want; new < NR_IRQS; new++) {

		if (platform_legacy_irq(new))

			continue;
@@ -3001,11 +3001,14 @@ unsigned int create_irq_nr(unsigned int irq_want) 
	return irq;

}



static int nr_irqs_gsi = NR_IRQS_LEGACY;

int create_irq(void)

{

	unsigned int irq_want;

	int irq;



	irq = create_irq_nr(nr_irqs - 1);

	irq_want = nr_irqs_gsi;

	irq = create_irq_nr(irq_want);



	if (irq == 0)

		irq = -1;
@@ -3281,7 +3284,7 @@ int arch_setup_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc) 
	int ret;

	unsigned int irq_want;



	irq_want = nr_irqs - 1;

	irq_want = nr_irqs_gsi;

	irq = create_irq_nr(irq_want);

	if (irq == 0)

		return -1;
@@ -3321,11 +3324,11 @@ int arch_setup_msi_irqs(struct pci_dev *dev, int nvec, int type) 
	int index = 0;

#endif



	irq_want = nr_irqs - 1;

	irq_want = nr_irqs_gsi;

	sub_handle = 0;

	list_for_each_entry(msidesc, &dev->msi_list, list) {

		irq = create_irq_nr(irq_want);

		irq_want--;

		irq_want++;

		if (irq == 0)

			return -1;

#ifdef CONFIG_INTR_REMAP
@@ -3674,9 +3677,16 @@ int __init io_apic_get_redir_entries (int ioapic) 
	return reg_01.bits.entries;

}



int __init probe_nr_irqs(void)

void __init probe_nr_irqs_gsi(void)

{

	return NR_IRQS;

	int idx;

	int nr = 0;



	for (idx = 0; idx < nr_ioapics; idx++)

		nr += io_apic_get_redir_entries(idx) + 1;



	if (nr > nr_irqs_gsi)

		nr_irqs_gsi = nr;

}



/* --------------------------------------------------------------------------

arch/x86/kernel/setup.c

+1 −1
Original line number Diff line number Diff line
@@ -1082,7 +1082,7 @@ void __init setup_arch(char **cmdline_p) 
	ioapic_init_mappings();



	/* need to wait for io_apic is mapped */

	nr_irqs = probe_nr_irqs();

	probe_nr_irqs_gsi();



	kvm_guest_init();