From: Tom Lendacky <thomas.lendacky@amd.com>
Date: Mon, 4 Dec 2017 10:57:24 -0600
Subject: kvm: svm: prepare for new bit definition in nested_ctl
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Git-commit: cea3a19b007a690a40fac373f22bf34ea69761a2
Patch-mainline: v4.16-rc1
References: bsc#1063068

Currently the nested_ctl variable in the vmcb_control_area structure is
used to indicate nested paging support. The nested paging support field
is actually defined as bit 0 of the field. In order to support a new
feature flag the usage of the nested_ctl and nested paging support must
be converted to operate on a single bit.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: x86@kernel.org
Cc: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Borislav Petkov <bp@suse.de>
---
 arch/x86/include/asm/svm.h |    2 ++
 arch/x86/kvm/svm.c         |    7 ++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -145,6 +145,8 @@ struct __attribute__ ((__packed__)) vmcb
 #define SVM_VM_CR_SVM_LOCK_MASK 0x0008ULL
 #define SVM_VM_CR_SVM_DIS_MASK  0x0010ULL
 
+#define SVM_NESTED_CTL_NP_ENABLE	BIT(0)
+
 struct __attribute__ ((__packed__)) vmcb_seg {
 	u16 selector;
 	u16 attrib;
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1292,7 +1292,7 @@ static void init_vmcb(struct vcpu_svm *s
 
 	if (npt_enabled) {
 		/* Setup VMCB for Nested Paging */
-		control->nested_ctl = 1;
+		control->nested_ctl |= SVM_NESTED_CTL_NP_ENABLE;
 		clr_intercept(svm, INTERCEPT_INVLPG);
 		clr_exception_intercept(svm, PF_VECTOR);
 		clr_cr_intercept(svm, INTERCEPT_CR3_READ);
@@ -2919,7 +2919,8 @@ static bool nested_vmcb_checks(struct vm
 	if (vmcb->control.asid == 0)
 		return false;
 
-	if (vmcb->control.nested_ctl && !npt_enabled)
+	if ((vmcb->control.nested_ctl & SVM_NESTED_CTL_NP_ENABLE) &&
+	    !npt_enabled)
 		return false;
 
 	return true;
@@ -2933,7 +2934,7 @@ static void enter_svm_guest_mode(struct
 	else
 		svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
 
-	if (nested_vmcb->control.nested_ctl) {
+	if (nested_vmcb->control.nested_ctl & SVM_NESTED_CTL_NP_ENABLE) {
 		kvm_mmu_unload(&svm->vcpu);
 		svm->nested.nested_cr3 = nested_vmcb->control.nested_cr3;
 		nested_svm_init_mmu_context(&svm->vcpu);