summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/cpu
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2023-04-03 19:34:08 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2023-04-03 19:34:08 +0300
commit2d72ab2449fa9fce8f6898fd5adda10497f7c111 (patch)
treed74f5711ab2a14dacc4646002784ab94f2f17ac9 /arch/x86/kernel/cpu
parent7e364e56293bb98cae1b55fd835f5991c4e96e7d (diff)
parentf8acb24aaf89fc46cd953229462ea8abe31b395f (diff)
downloadlinux-2d72ab2449fa9fce8f6898fd5adda10497f7c111.tar.xz
Merge tag 'hyperv-fixes-signed-20230402' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyperv fixes from Wei Liu: - Fix a bug in channel allocation for VMbus (Mohammed Gamal) - Do not allow root partition functionality in CVM (Michael Kelley) * tag 'hyperv-fixes-signed-20230402' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux: x86/hyperv: Block root partition functionality in a Confidential VM Drivers: vmbus: Check for channel allocation before looking up relids
Diffstat (limited to 'arch/x86/kernel/cpu')
-rw-r--r--arch/x86/kernel/cpu/mshyperv.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index f36dc2f796c5..f1197366a97d 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -358,12 +358,16 @@ static void __init ms_hyperv_init_platform(void)
* To mirror what Windows does we should extract CPU management
* features and use the ReservedIdentityBit to detect if Linux is the
* root partition. But that requires negotiating CPU management
- * interface (a process to be finalized).
+ * interface (a process to be finalized). For now, use the privilege
+ * flag as the indicator for running as root.
*
- * For now, use the privilege flag as the indicator for running as
- * root.
+ * Hyper-V should never specify running as root and as a Confidential
+ * VM. But to protect against a compromised/malicious Hyper-V trying
+ * to exploit root behavior to expose Confidential VM memory, ignore
+ * the root partition setting if also a Confidential VM.
*/
- if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_CPU_MANAGEMENT) {
+ if ((ms_hyperv.priv_high & HV_CPU_MANAGEMENT) &&
+ !(ms_hyperv.priv_high & HV_ISOLATION)) {
hv_root_partition = true;
pr_info("Hyper-V: running as root partition\n");
}