From: Thomas Gleixner tglx@linutronix.de
[ 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@linux.intel.com Tested-by: Rahul Tanwar rahul.tanwar@linux.intel.com Tested-by: Andy Shevchenko andriy.shevchenko@intel.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Cc: alan@linux.intel.com Cc: bp@alien8.de Cc: cheol.yong.kim@intel.com Cc: qi-ming.wu@intel.com Cc: rahul.tanwar@intel.com Cc: rppt@linux.ibm.com Cc: tony.luck@intel.com Link: http://lkml.kernel.org/r/20190821081330.1187-1-rahul.tanwar@linux.intel.com Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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