Commit 19a36d32 authored Aug 26, 2019 by Waiman Long Committed by Paolo Bonzini Sep 27, 2019

KVM: VMX: Set VMENTER_L1D_FLUSH_NOT_REQUIRED if !X86_BUG_L1TF



The l1tf_vmx_mitigation is only set to VMENTER_L1D_FLUSH_NOT_REQUIRED
when the ARCH_CAPABILITIES MSR indicates that L1D flush is not required.
However, if the CPU is not affected by L1TF, l1tf_vmx_mitigation will
still be set to VMENTER_L1D_FLUSH_AUTO. This is certainly not the best
option for a !X86_BUG_L1TF CPU.

So force l1tf_vmx_mitigation to VMENTER_L1D_FLUSH_NOT_REQUIRED to make it
more explicit in case users are checking the vmentry_l1d_flush parameter.

Signed-off-by: Waiman Long <longman@redhat.com>
[Patch rewritten accoring to Borislav Petkov's suggestion. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 09444420

arch/x86/kvm/vmx/vmx.c

+9 −6

Original line number	Diff line number	Diff line
		@@ -209,6 +209,11 @@ static int vmx_setup_l1d_flush(enum vmx_l1d_flush_state l1tf)
		struct page *page;
		unsigned int i;

		if (!boot_cpu_has_bug(X86_BUG_L1TF)) {
		l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_NOT_REQUIRED;
		return 0;
		}

		if (!enable_ept) {
		l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_EPT_DISABLED;
		return 0;
		@@ -7995,13 +8000,11 @@ static int __init vmx_init(void)
		* contain 'auto' which will be turned into the default 'cond'
		* mitigation mode.
		*/
		if (boot_cpu_has(X86_BUG_L1TF)) {
		r = vmx_setup_l1d_flush(vmentry_l1d_flush_param);
		if (r) {
		vmx_exit();
		return r;
		}
		}

		#ifdef CONFIG_KEXEC_CORE
		rcu_assign_pointer(crash_vmclear_loaded_vmcss,