linux-kernel - [RFC Part2 PATCH v3 06/26] KVM: SVM: Prepare for new bit definition in nested

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Date:   Mon, 24 Jul 2017 15:02:43 -0500
From:   Brijesh Singh <brijesh.singh@....com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...e.de>,
        Joerg Roedel <joro@...tes.org>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        \"Radim Krčmář\" 
        <rkrcmar@...hat.com>, Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [RFC Part2 PATCH v3 06/26] KVM: SVM: Prepare for new bit definition in nested_ctl

From: Tom Lendacky <thomas.lendacky@....com>

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.

Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
---
 arch/x86/include/asm/svm.h | 2 ++
 arch/x86/kvm/svm.c         | 7 ++++---
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 58fffe7..a3d9e0b 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -139,6 +139,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 #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;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 06bd902..1cd7c78 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1296,7 +1296,7 @@ static void init_vmcb(struct vcpu_svm *svm)
 
 	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);
@@ -2904,7 +2904,8 @@ static bool nested_vmcb_checks(struct vmcb *vmcb)
 	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;
@@ -2979,7 +2980,7 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
 	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);
-- 
2.9.4