[3/3] smt: Do not disable SMT in virtual machines

Message ID 20200721103641.30305-3-michael.tremer@ipfire.org
State Staged
Commit 8531a9503c2328f88deb83820364ce21bc8a357d
Headers show
Series
  • [1/3] oci: Add detection for Oracle Cloud
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Commit Message

Michael Tremer July 21, 2020, 10:36 a.m. UTC
Processors in virtual machines are *virtual*. Therefore this
only degrades the performance of the guest, but does not increase
it's security.

This patch always leaves SMT enabled in all virtual environments.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---
 src/initscripts/system/smt | 5 +++++
 1 file changed, 5 insertions(+)

Patch

diff --git a/src/initscripts/system/smt b/src/initscripts/system/smt
index cc4128b2d..bfa7d57b3 100644
--- a/src/initscripts/system/smt
+++ b/src/initscripts/system/smt
@@ -20,6 +20,11 @@  case "${1}" in
 			exit 0
 		fi 2>/dev/null
 
+		# Do not disable SMT inside virtual machines
+		if [ -d "/sys/hypervisor" ]; then
+			exit 0
+		fi
+
 		# Disable SMT when the processor is vulnerable to Foreshadow or Fallout/ZombieLoad/RIDL
 		for vuln in l1tf mds; do
 			if [ -r "/sys/devices/system/cpu/vulnerabilities/${vuln}" ] && \