[PATCH v3 12/27] KVM: nSVM: Drop svm->nested.initialized

[Yosry Ahmed]

Do NULL checks on svm->nested.vmcb02.ptr instead of using a dedicated
proxy 'initialized' field.  Make sure svm->nested.vmcb02.ptr is
correctly set to NULL on initialization failures, as it is currently
left as a dangling pointer.

This makes it possible to directly do a NULL check on
svm->nested.vmcb02.ptr before using it, instead of checking a different
field, which is less error-prone.

Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
---
 arch/x86/kvm/svm/nested.c | 14 ++++++--------
 arch/x86/kvm/svm/svm.h    |  2 --
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 5d63ae47ebb6c..bfb297b7d71ab 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -1142,7 +1142,7 @@ int nested_svm_vmrun(struct kvm_vcpu *vcpu)
 		return ret;
 	}
 
-	if (WARN_ON_ONCE(!svm->nested.initialized))
+	if (WARN_ON_ONCE(!svm->nested.vmcb02.ptr))
 		return -EINVAL;
 
 	vmcb12_gpa = kvm_rax_read(vcpu);
@@ -1489,21 +1489,21 @@ int svm_allocate_nested(struct vcpu_svm *svm)
 {
 	struct page *vmcb02_page;
 
-	if (svm->nested.initialized)
+	if (svm->nested.vmcb02.ptr)
 		return 0;
 
 	vmcb02_page = snp_safe_alloc_page();
 	if (!vmcb02_page)
 		return -ENOMEM;
-	svm->nested.vmcb02.ptr = page_address(vmcb02_page);
-	svm->nested.vmcb02.pa = __sme_set(page_to_pfn(vmcb02_page) << PAGE_SHIFT);
 
 	svm->nested.msrpm = svm_vcpu_alloc_msrpm();
 	if (!svm->nested.msrpm)
 		goto err_free_vmcb02;
 
 	svm->nested.vmcb02.cpu = -1;
-	svm->nested.initialized = true;
+	svm->nested.vmcb02.ptr = page_address(vmcb02_page);
+	svm->nested.vmcb02.pa = __sme_set(page_to_pfn(vmcb02_page) << PAGE_SHIFT);
+
 	return 0;
 
 err_free_vmcb02:
@@ -1513,7 +1513,7 @@ int svm_allocate_nested(struct vcpu_svm *svm)
 
 void svm_free_nested(struct vcpu_svm *svm)
 {
-	if (!svm->nested.initialized)
+	if (!svm->nested.vmcb02.ptr)
 		return;
 
 	if (WARN_ON_ONCE(svm->vmcb != svm->vmcb01.ptr))
@@ -1533,8 +1533,6 @@ void svm_free_nested(struct vcpu_svm *svm)
 	 * When the vmcb02 is freed, this optimization becomes invalid.
 	 */
 	svm->nested.last_vmcb12_gpa = INVALID_GPA;
-
-	svm->nested.initialized = false;
 }
 
 void svm_leave_nested(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index d386f2a4f72d7..2e1b5481ddd92 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -234,8 +234,6 @@ struct svm_nested_state {
 	 */
 	struct vmcb_save_area_cached save;
 
-	bool initialized;
-
 	/*
 	 * Indicates whether MSR bitmap for L2 needs to be rebuilt due to
 	 * changes in MSR bitmap for L1 or switching to a different L2. Note,
-- 
2.56.0.385.gd3acb90ef8-goog