x86/speculation/l1tf: Drop the swap storage limit restriction when l1tf=off
commit86ba6f66c9c16acd38c1bfa1cdf53a570d3e39a5
authorMichal Hocko <mhocko@suse.com>
Tue, 13 Nov 2018 18:49:10 +0000 (13 19:49 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 9 Jan 2019 16:38:41 +0000 (9 17:38 +0100)
treec844e99b6d136692e51615eac5790b1c778a5ce2
parentaeb5e53416965cea9a5186c6154b9f395a538740
x86/speculation/l1tf: Drop the swap storage limit restriction when l1tf=off

commit 5b5e4d623ec8a34689df98e42d038a3b594d2ff9 upstream.

Swap storage is restricted to max_swapfile_size (~16TB on x86_64) whenever
the system is deemed affected by L1TF vulnerability. Even though the limit
is quite high for most deployments it seems to be too restrictive for
deployments which are willing to live with the mitigation disabled.

We have a customer to deploy 8x 6,4TB PCIe/NVMe SSD swap devices which is
clearly out of the limit.

Drop the swap restriction when l1tf=off is specified. It also doesn't make
much sense to warn about too much memory for the l1tf mitigation when it is
forcefully disabled by the administrator.

[ tglx: Folded the documentation delta change ]

Fixes: 377eeaa8e11f ("x86/speculation/l1tf: Limit swap file size to MAX_PA/2")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Kosina <jkosina@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: <linux-mm@kvack.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20181113184910.26697-1-mhocko@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Documentation/admin-guide/kernel-parameters.txt
Documentation/admin-guide/l1tf.rst
arch/x86/kernel/cpu/bugs.c
arch/x86/mm/init.c