From e3923475ebb1b503668dfdb3ba90e2ebd46931e6 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Wed, 13 Jun 2018 15:48:28 -0700 Subject: x86/speculation/l1tf: Limit swap file size to MAX_PA/2 commit 377eeaa8e11fe815b1d07c81c4a0e2843a8c15eb upstream For the L1TF workaround its necessary to limit the swap file size to below MAX_PA/2, so that the higher bits of the swap offset inverted never point to valid memory. Add a mechanism for the architecture to override the swap file size check in swapfile.c and add a x86 specific max swapfile check function that enforces that limit. The check is only enabled if the CPU is vulnerable to L1TF. In VMs with 42bit MAX_PA the typical limit is 2TB now, on a native system with 46bit PA it is 32TB. The limit is only per individual swap file, so it's always possible to exceed these limits with multiple swap files or partitions. Signed-off-by: Andi Kleen Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf Acked-by: Michal Hocko Acked-by: Dave Hansen Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman --- include/linux/swapfile.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/swapfile.h b/include/linux/swapfile.h index 388293a91e8c..e4594de79bc4 100644 --- a/include/linux/swapfile.h +++ b/include/linux/swapfile.h @@ -9,5 +9,7 @@ extern spinlock_t swap_lock; extern struct plist_head swap_active_head; extern struct swap_info_struct *swap_info[]; extern int try_to_unuse(unsigned int, bool, unsigned long); +extern unsigned long generic_max_swapfile_size(void); +extern unsigned long max_swapfile_size(void); #endif /* _LINUX_SWAPFILE_H */ -- cgit v1.2.3