x86: cap iomem_resource to addressable physical memory

iomem_resource is by default initialized to -1, which means 64 bits of
physical address space if 64-bit resources are enabled.  However, x86
CPUs cannot address 64 bits of physical address space.  Thus, we want
to cap the physical address space to what the union of all CPU can
actually address.

Without this patch, we may end up assigning inaccessible values to
uninitialized 64-bit PCI memory resources.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Martin Mares <mj@ucw.cz>
Cc: stable@kernel.org

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 3ffdcfa9abdf07accfa466518b8ac1adf16a9c05..5b9cb8839cae7c800c990e5c03e0d4b03e0ccc1b 100644 (file)
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -853,6 +853,9 @@ static void __cpuinit identify_cpu(struct cpuinfo_x86 *c)
 #if defined(CONFIG_NUMA) && defined(CONFIG_X86_64)
        numa_add_cpu(smp_processor_id());
 #endif
+
+       /* Cap the iomem address space to what is addressable on all CPUs */
+       iomem_resource.end &= (1ULL << c->x86_phys_bits) - 1;
 }
 
 #ifdef CONFIG_X86_64