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authorDaniel Sneddon <daniel.sneddon@linux.intel.com>2023-07-12 19:43:14 -0700
committerDave Hansen <dave.hansen@linux.intel.com>2023-07-21 13:02:35 -0700
commit81ac7e5d741742d650b4ed6186c4826c1a0631a7 (patch)
treed64990a59ca3a8f8718fd9fbc9281449618a1a3f /arch/x86/kernel/cpu/bugs.c
parent53cf5797f114ba2bd86d23a862302119848eff19 (diff)
KVM: Add GDS_NO support to KVM
Gather Data Sampling (GDS) is a transient execution attack using gather instructions from the AVX2 and AVX512 extensions. This attack allows malicious code to infer data that was previously stored in vector registers. Systems that are not vulnerable to GDS will set the GDS_NO bit of the IA32_ARCH_CAPABILITIES MSR. This is useful for VM guests that may think they are on vulnerable systems that are, in fact, not affected. Guests that are running on affected hosts where the mitigation is enabled are protected as if they were running on an unaffected system. On all hosts that are not affected or that are mitigated, set the GDS_NO bit. Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
-rw-r--r--arch/x86/kernel/cpu/bugs.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 41821a4551a2..7985c658d129 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -674,6 +674,13 @@ static const char * const gds_strings[] = {
[GDS_MITIGATION_HYPERVISOR] = "Unknown: Dependent on hypervisor status",
};
+bool gds_ucode_mitigated(void)
+{
+ return (gds_mitigation == GDS_MITIGATION_FULL ||
+ gds_mitigation == GDS_MITIGATION_FULL_LOCKED);
+}
+EXPORT_SYMBOL_GPL(gds_ucode_mitigated);
+
void update_gds_msr(void)
{
u64 mcu_ctrl_after;