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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 2cf7ea9f40fabee0f8b40db4eb2d1e85cc6c0a95 Mon Sep 17 00:00:00 2001
From: Paolo Bonzini <pbonzini@xxxxxxxxxx>
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.
reported-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Fixes: 8d860bbeedef ("kvm: vmx: Basic APIC virtualization controls have three settings")
Cc: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 764ae031054f..55b62760b694 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -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,
