FAILED: patch "[PATCH] KVM: VMX: hide flexpriority from guest when disabled at the" failed to apply to 4.18-stable tree

The patch below does not apply to the 4.18-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Paolo Bonzini <[email protected]>
Date: Wed, 3 Oct 2018 10:34:00 +0200
Subject: [PATCH] KVM: VMX: hide flexpriority from guest when disabled at the
module level

As of commit 8d860bbeedef ("kvm: vmx: Basic APIC virtualization controls have three settings"), KVM will disable VIRTUALIZE_APIC_ACCESSES when a nested guest writes APIC_BASE MSR and kvm-intel.flexpriority=0, whereas previously KVM would allow a nested guest to enable VIRTUALIZE_APIC_ACCESSES so long as it's supported in hardware. That is, KVM now advertises VIRTUALIZE_APIC_ACCESSES to a guest but doesn't (always) allow setting it when kvm-intel.flexpriority=0, and may even initially allow the control and then clear it when the nested guest writes APIC_BASE MSR, which is decidedly odd even if it doesn't cause functional issues.

Hide the control completely when the module parameter is cleared.

index 764ae031054f..55b62760b694 100644
@@ -3589,12 +3589,12 @@ static void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, bool apicv)
 		msrs->secondary_ctls_high);
 	msrs->secondary_ctls_low = 0;
 	msrs->secondary_ctls_high &=
-		SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
 		SECONDARY_EXEC_DESC |
 		SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE |
 		SECONDARY_EXEC_APIC_REGISTER_VIRT |
 		SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
 		SECONDARY_EXEC_WBINVD_EXITING;
+
 	/*
 	 * We can emulate "VMCS shadowing," even if the hardware
 	 * doesn't support it.

@@ -3651,6 +3651,10 @@ static void nested_vmx_setup_ctls_msrs(struct nested_vmx_msrs *msrs, bool apicv)
 		msrs->secondary_ctls_high |=
 			SECONDARY_EXEC_UNRESTRICTED_GUEST;
 
+	if (flexpriority_enabled)
+		msrs->secondary_ctls_high |=
+			SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+
 	/* miscellaneous data */
 	rdmsr(MSR_IA32_VMX_MISC,
 		msrs->misc_low,