MIPS: Malta: Register UP SMP ops if all else fails

If we fail to register any real SMP implementations, fall back to
registering the dummy UP implementation. Otherwise when we build an SMP
kernel & run it on a system where the SMP implementations fail to probe
(eg. QEMU) the kernel will perform a NULL dereference attempting to call
mp_ops->smp_setup() from plat_smp_setup().

Notably this fixes booting kernels with CPS SMP enabled on QEMU, which
doesn't currently implement the CM, CPC or GIC.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Rob Herring <robh@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11223/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 703438a9698e2dd5ea788898ecf8812a6caa7dbc..9322d267e774ecf4d1167b5a833aaa7c7e278a47 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -425,6 +425,7 @@ config MIPS_MALTA
        select MIPS_L1_CACHE_SHIFT_6
        select PCI_GT64XXX_PCI0
        select MIPS_MSC
+       select SMP_UP if SMP
        select SWAP_IO_SPACE
        select SYS_HAS_CPU_MIPS32_R1
        select SYS_HAS_CPU_MIPS32_R2

diff --git a/arch/mips/mti-malta/malta-init.c b/arch/mips/mti-malta/malta-init.c
index 53c24784a2f7bd2e8c0ae719f1f07c9ad60dd52b..571148c5fd0baa5ce8656e87574144d90b58e346 100644 (file)
--- a/arch/mips/mti-malta/malta-init.c
+++ b/arch/mips/mti-malta/malta-init.c
@@ -302,6 +302,7 @@ mips_pci_controller:
                return;
        if (!register_vsmp_smp_ops())
                return;
+       register_up_smp_ops();
 }
 
 void platform_early_l2_init(void)