x86/apic: Re-enable PCI_MSI support for non-SMP X86_32

commit 38a1dfda upstream.

Commit 0dbc6078 ('x86, build, pci: Fix PCI_MSI build on !SMP')
introduced the dependency that X86_UP_APIC is only available when
PCI_MSI is false. This effectively prevents PCI_MSI support on 32bit
UP systems because it disables both APIC and IO-APIC. But APIC support
is architecturally required for PCI_MSI.

The intention of the patch was to enforce APIC support when PCI_MSI is
enabled, but failed to do so.

Remove the !PCI_MSI dependency from X86_UP_APIC and enforce
X86_UP_APIC when PCI_MSI support is enabled on 32bit UP systems.

[ tglx: Massaged changelog ]

Fixes 0dbc6078 'x86, build, pci: Fix PCI_MSI build on !SMP'
Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: http://lkml.kernel.org/r/1421967529-9037-1-git-send-email-pure.logic@nexus-software.ieSigned-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/x86/Kconfig

@@ -805,7 +805,7 @@ source "kernel/Kconfig.preempt"
 
 config X86_UP_APIC
 	bool "Local APIC support on uniprocessors"
-	depends on X86_32 && !SMP && !X86_32_NON_STANDARD && !PCI_MSI
+	depends on X86_32 && !SMP && !X86_32_NON_STANDARD
 	---help---
 	  A local APIC (Advanced Programmable Interrupt Controller) is an
 	  integrated interrupt controller in the CPU. If you have a single-CPU
@@ -816,6 +816,10 @@ config X86_UP_APIC
 	  performance counters), and the NMI watchdog which detects hard
 	  lockups.
 
+config X86_UP_APIC_MSI
+	def_bool y
+	select X86_UP_APIC if X86_32 && !SMP && !X86_32_NON_STANDARD && PCI_MSI
+
 config X86_UP_IOAPIC
 	bool "IO-APIC support on uniprocessors"
 	depends on X86_UP_APIC