x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry
Bit 3 of ARCH_CAPABILITIES tells a hypervisor that L1D flush on vmentry is
not needed. Add a new value to enum vmx_l1d_flush_state, which is used
either if there is no L1TF bug at all, or if bit 3 is set in ARCH_CAPABILITIES.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 8384f7c..29d6eab 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -218,6 +218,16 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
return 0;
}
+ if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES)) {
+ u64 msr;
+
+ rdmsrl(MSR_IA32_ARCH_CAPABILITIES, msr);
+ if (msr & ARCH_CAP_SKIP_VMENTRY_L1DFLUSH) {
+ l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED;
+ return 0;
+ }
+ }
+
/* If set to auto use the default l1tf mitigation method */
if (l1tf == VMENTER_L1D_FLUSH_AUTO) {
switch (l1tf_mitigation) {