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-rw-r--r--arch/x86/kvm/vmx/vmx.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b81000cc826a..421db354b1ab 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6844,8 +6844,13 @@ void noinstr vmx_spec_ctrl_restore_host(struct vcpu_vmx *vmx,
/*
* If the guest/host SPEC_CTRL values differ, restore the host value.
+ *
+ * For legacy IBRS, the IBRS bit always needs to be written after
+ * transitioning from a less privileged predictor mode, regardless of
+ * whether the guest/host values differ.
*/
- if (vmx->spec_ctrl != hostval)
+ if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) ||
+ vmx->spec_ctrl != hostval)
native_wrmsrl(MSR_IA32_SPEC_CTRL, hostval);
barrier_nospec();