Author: kib
Date: Tue Aug 14 17:14:33 2018
New Revision: 337774
URL: https://svnweb.freebsd.org/changeset/base/337774
Log:
Reserve page at the physical address zero on amd64.
We always zero the invalidated PTE/PDE for superpage, which means that
L1TF CPU vulnerability (CVE-2018-3620) can be only used for reading
from the page at zero.
Note that both i386 and amd64 exclude the page from phys_avail[]
array, so this change is redundant, but I think that phys_avail[] on
UEFI-boot does not need to do that. Eventually the blacklisting
should be made conditional on CPUs which report that they are not
vulnerable to L1TF.
Reviewed by: emaste. jhb
Sponsored by: The FreeBSD Foundation
Modified:
head/sys/amd64/amd64/pmap.c
Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c Tue Aug 14 16:37:14 2018 (r337773)
+++ head/sys/amd64/amd64/pmap.c Tue Aug 14 17:14:33 2018 (r337774)
@@ -1307,6 +1307,9 @@ pmap_init(void)
vm_size_t s;
int error, i, pv_npg, ret, skz63;
+ /* L1TF, reserve page @0 unconditionally */
+ vm_page_blacklist_add(0, bootverbose);
+
/* Detect bare-metal Skylake Server and Skylake-X. */
if (vm_guest == VM_GUEST_NO && cpu_vendor_id == CPU_VENDOR_INTEL &&
CPUID_TO_FAMILY(cpu_id) == 0x6 && CPUID_TO_MODEL(cpu_id) == 0x55) {
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