From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> [ Upstream commit 3e5bedc2c258341702ddffbd7688c5e6eb01eafa ] Rahul Tanwar reported the following bug on DT systems: > 'ioapic_dynirq_base' contains the virtual IRQ base number. Presently, it is > updated to the end of hardware IRQ numbers but this is done only when IOAPIC > configuration type is IOAPIC_DOMAIN_LEGACY or IOAPIC_DOMAIN_STRICT. There is > a third type IOAPIC_DOMAIN_DYNAMIC which applies when IOAPIC configuration > comes from devicetree. > > See dtb_add_ioapic() in arch/x86/kernel/devicetree.c > > In case of IOAPIC_DOMAIN_DYNAMIC (DT/OF based system), 'ioapic_dynirq_base' > remains to zero initialized value. This means that for OF based systems, > virtual IRQ base will get set to zero. Such systems will very likely not even boot. For DT enabled machines ioapic_dynirq_base is irrelevant and not updated, so simply map the IRQ base 1:1 instead. Reported-by: Rahul Tanwar <rahul.tanwar@xxxxxxxxxxxxxxx> Tested-by: Rahul Tanwar <rahul.tanwar@xxxxxxxxxxxxxxx> Tested-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: alan@xxxxxxxxxxxxxxx Cc: bp@xxxxxxxxx Cc: cheol.yong.kim@xxxxxxxxx Cc: qi-ming.wu@xxxxxxxxx Cc: rahul.tanwar@xxxxxxxxx Cc: rppt@xxxxxxxxxxxxx Cc: tony.luck@xxxxxxxxx Link: http://lkml.kernel.org/r/20190821081330.1187-1-rahul.tanwar@xxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/x86/kernel/apic/io_apic.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 96a8a68f9c793..566b7bc5deaa0 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -2342,7 +2342,13 @@ unsigned int arch_dynirq_lower_bound(unsigned int from) * dmar_alloc_hwirq() may be called before setup_IO_APIC(), so use * gsi_top if ioapic_dynirq_base hasn't been initialized yet. */ - return ioapic_initialized ? ioapic_dynirq_base : gsi_top; + if (!ioapic_initialized) + return gsi_top; + /* + * For DT enabled machines ioapic_dynirq_base is irrelevant and not + * updated. So simply return @from if ioapic_dynirq_base == 0. + */ + return ioapic_dynirq_base ? : from; } #ifdef CONFIG_X86_32 -- 2.20.1
