KVM: SVM: not account memory allocation for per-CPU svm_data

The allocation for the per-CPU save area in svm_cpu_init shouldn't
be accounted, So introduce  __snp_safe_alloc_page helper, which has
gfp flag as input, svm_cpu_init calls __snp_safe_alloc_page with
GFP_KERNEL, snp_safe_alloc_page calls __snp_safe_alloc_page with
GFP_KERNEL_ACCOUNT as input
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20240520120858.13117-3-lirongqing@baidu.comSigned-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/svm/sev.c

@@ -3380,13 +3380,13 @@ void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector)
 	}
 }
 
-struct page *snp_safe_alloc_page(void)
+struct page *__snp_safe_alloc_page(gfp_t gfp)
 {
 	unsigned long pfn;
 	struct page *p;
 
 	if (!cc_platform_has(CC_ATTR_HOST_SEV_SNP))
-		return alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+		return alloc_page(gfp | __GFP_ZERO);
 
 	/*
 	 * Allocate an SNP-safe page to workaround the SNP erratum where
@@ -3397,7 +3397,7 @@ struct page *snp_safe_alloc_page(void)
 	 * Allocate one extra page, choose a page which is not
 	 * 2MB-aligned, and free the other.
 	 */
-	p = alloc_pages(GFP_KERNEL_ACCOUNT | __GFP_ZERO, 1);
+	p = alloc_pages(gfp | __GFP_ZERO, 1);
 	if (!p)
 		return NULL;
 

arch/x86/kvm/svm/svm.c

@@ -703,7 +703,7 @@ static int svm_cpu_init(int cpu)
 	int ret = -ENOMEM;
 
 	memset(sd, 0, sizeof(struct svm_cpu_data));
-	sd->save_area = snp_safe_alloc_page();
+	sd->save_area = __snp_safe_alloc_page(GFP_KERNEL);
 	if (!sd->save_area)
 		return ret;
 

arch/x86/kvm/svm/svm.h

@@ -694,7 +694,13 @@ void sev_guest_memory_reclaimed(struct kvm *kvm);
 int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
 
 /* These symbols are used in common code and are stubbed below.  */
-struct page *snp_safe_alloc_page(void);
+struct page *__snp_safe_alloc_page(gfp_t gfp);
+
+static inline struct page *snp_safe_alloc_page(void)
+{
+	return __snp_safe_alloc_page(GFP_KERNEL_ACCOUNT);
+}
+
 void sev_free_vcpu(struct kvm_vcpu *vcpu);
 void sev_vm_destroy(struct kvm *kvm);
 void __init sev_set_cpu_caps(void);
@@ -704,9 +710,14 @@ int sev_cpu_init(struct svm_cpu_data *sd);
 int sev_dev_get_attr(u32 group, u64 attr, u64 *val);
 extern unsigned int max_sev_asid;
 #else
+static inline struct page *__snp_safe_alloc_page(gfp_t gfp)
+{
+	return alloc_page(gfp | __GFP_ZERO);
+}
+
 static inline struct page *snp_safe_alloc_page(void)
 {
-	return alloc_page(GFP_KERNEL_ACCOUNT | __GFP_ZERO);
+	return __snp_safe_alloc_page(GFP_KERNEL_ACCOUNT);
 }
 
 static inline void sev_free_vcpu(struct kvm_vcpu *vcpu) {}