Commit fd6b6d9b authored Oct 01, 2018 by Sean Christopherson Committed by Paolo Bonzini Oct 04, 2018

KVM: VMX: check for existence of secondary exec controls before accessing



Return early from vmx_set_virtual_apic_mode() if the processor doesn't
support VIRTUALIZE_APIC_ACCESSES or VIRTUALIZE_X2APIC_MODE, both of
which reside in SECONDARY_VM_EXEC_CONTROL.  This eliminates warnings
due to VMWRITEs to SECONDARY_VM_EXEC_CONTROL (VMCS field 401e) failing
on processors without secondary exec controls.

Remove the similar check for TPR shadowing as it is incorporated in the
flexpriority_enabled check and the APIC-related code in
vmx_update_msr_bitmap() is further gated by VIRTUALIZE_X2APIC_MODE.

Reported-by: Gerhard Wiesinger <redhat@wiesinger.com>
Fixes: 8d860bbe ("kvm: vmx: Basic APIC virtualization controls have three settings")
Cc: Jim Mattson <jmattson@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent daa07cbc

arch/x86/kvm/vmx.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -10214,15 +10214,16 @@ static void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu)
		if (!lapic_in_kernel(vcpu))
		return;

		if (!flexpriority_enabled &&
		!cpu_has_vmx_virtualize_x2apic_mode())
		return;

		/* Postpone execution until vmcs01 is the current VMCS. */
		if (is_guest_mode(vcpu)) {
		to_vmx(vcpu)->nested.change_vmcs01_virtual_apic_mode = true;
		return;
		}

		if (!cpu_need_tpr_shadow(vcpu))
		return;

		sec_exec_control = vmcs_read32(SECONDARY_VM_EXEC_CONTROL);
		sec_exec_control &= ~(SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES \|
		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE);

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