x86/speculation/l1tf: Fix overflow in l1tf_pfn_limit() on 32bit

On 32bit PAE kernels on 64bit hardware with enough physical bits,
l1tf_pfn_limit() will overflow unsigned long. This in turn affects
max_swapfile_size() and can lead to swapon returning -EINVAL. This has been
observed in a 32bit guest with 42 bits physical address size, where
max_swapfile_size() overflows exactly to 1 << 32, thus zero, and produces
the following warning to dmesg:

[    6.396845] Truncating oversized swap area, only using 0k out of 2047996k

Fix this by using unsigned long long instead.

Fixes: 17dbca119312 ("x86/speculation/l1tf: Add sysfs reporting for l1tf")
Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2")
Reported-by: Dominique Leuenberger <dimstar@suse.de>
Reported-by: Adrian Schroeter <adrian@suse.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: "H . Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20180820095835.5298-1-vbabka@suse.cz

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h
index 682286aca881..a0a52274cb4a 100644
--- a/arch/x86/include/asm/processor.h
+++ b/arch/x86/include/asm/processor.h
@@ -181,9 +181,9 @@ extern const struct seq_operations cpuinfo_op;
 
 extern void cpu_detect(struct cpuinfo_x86 *c);
 
-static inline unsigned long l1tf_pfn_limit(void)
+static inline unsigned long long l1tf_pfn_limit(void)
 {
-	return BIT(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1;
+	return BIT_ULL(boot_cpu_data.x86_phys_bits - 1 - PAGE_SHIFT) - 1;
 }
 
 extern void early_cpu_init(void);