KVM: SVM: refactor msr permission bitmap allocation

Replace svm_vcpu_init_msrpm with svm_vcpu_alloc_msrpm, that also allocates
the msr bitmap and add svm_vcpu_free_msrpm to free it.

This will be used later to move the nested msr permission bitmap allocation
to nested.c

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20200827171145.374620-4-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/svm.c

@@ -609,18 +609,29 @@ static void set_msr_interception(u32 *msrpm, unsigned msr,
 	msrpm[offset] = tmp;
 }
 
-static void svm_vcpu_init_msrpm(u32 *msrpm)
+static u32 *svm_vcpu_init_msrpm(void)
 {
 	int i;
+	u32 *msrpm;
+	struct page *pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER);
+
+	if (!pages)
+		return NULL;
 
+	msrpm = page_address(pages);
 	memset(msrpm, 0xff, PAGE_SIZE * (1 << MSRPM_ALLOC_ORDER));
 
 	for (i = 0; direct_access_msrs[i].index != MSR_INVALID; i++) {
 		if (!direct_access_msrs[i].always)
 			continue;
-
 		set_msr_interception(msrpm, direct_access_msrs[i].index, 1, 1);
 	}
+	return msrpm;
+}
+
+static void svm_vcpu_free_msrpm(u32 *msrpm)
+{
+	__free_pages(virt_to_page(msrpm), MSRPM_ALLOC_ORDER);
 }
 
 static void add_msr_offset(u32 offset)
@@ -1172,9 +1183,7 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm;
 	struct page *vmcb_page;
-	struct page *msrpm_pages;
 	struct page *hsave_page;
-	struct page *nested_msrpm_pages;
 	int err;
 
 	BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
@@ -1185,21 +1194,13 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 	if (!vmcb_page)
 		goto out;
 
-	msrpm_pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER);
-	if (!msrpm_pages)
-		goto free_page1;
-
-	nested_msrpm_pages = alloc_pages(GFP_KERNEL_ACCOUNT, MSRPM_ALLOC_ORDER);
-	if (!nested_msrpm_pages)
-		goto free_page2;
-
 	hsave_page = alloc_page(GFP_KERNEL_ACCOUNT);
 	if (!hsave_page)
-		goto free_page3;
+		goto free_page1;
 
 	err = avic_init_vcpu(svm);
 	if (err)
-		goto free_page4;
+		goto free_page2;
 
 	/* We initialize this flag to true to make sure that the is_running
 	 * bit would be set the first time the vcpu is loaded.
@@ -1210,11 +1211,13 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 	svm->nested.hsave = page_address(hsave_page);
 	clear_page(svm->nested.hsave);
 
-	svm->msrpm = page_address(msrpm_pages);
-	svm_vcpu_init_msrpm(svm->msrpm);
+	svm->msrpm = svm_vcpu_init_msrpm();
+	if (!svm->msrpm)
+		goto free_page2;
 
-	svm->nested.msrpm = page_address(nested_msrpm_pages);
-	svm_vcpu_init_msrpm(svm->nested.msrpm);
+	svm->nested.msrpm = svm_vcpu_init_msrpm();
+	if (!svm->nested.msrpm)
+		goto free_page3;
 
 	svm->vmcb = page_address(vmcb_page);
 	clear_page(svm->vmcb);
@@ -1227,12 +1230,10 @@ static int svm_create_vcpu(struct kvm_vcpu *vcpu)
 
 	return 0;
 
-free_page4:
-	__free_page(hsave_page);
 free_page3:
-	__free_pages(nested_msrpm_pages, MSRPM_ALLOC_ORDER);
+	svm_vcpu_free_msrpm(svm->msrpm);
 free_page2:
-	__free_pages(msrpm_pages, MSRPM_ALLOC_ORDER);
+	__free_page(hsave_page);
 free_page1:
 	__free_page(vmcb_page);
 out: