Commit bea7e31a authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Borislav Petkov
Browse files

KVM: VMX: Fix IBRS handling after vmexit 



For legacy IBRS to work, the IBRS bit needs to be always re-written
after vmexit, even if it's already on.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
parent fc02735b

arch/x86/kvm/vmx/vmx.c

+6 −1
Original line number Diff line number Diff line
@@ -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();