iommu/amd: Fix possible memory leak of 'domain'

Move allocation code down to avoid memory leak.

Fixes: 29f54745 ("iommu/amd: Add missing domain type checks")
Signed-off-by: Su Hui <suhui@nfschina.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Reviewed-by: Vasant Hegde <vasant.hegde@amd.com>
Link: https://lore.kernel.org/r/20230608021933.856045-1-suhui@nfschina.comSigned-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd/iommu.c

@@ -2078,10 +2078,6 @@ static struct protection_domain *protection_domain_alloc(unsigned int type)
 	int mode = DEFAULT_PGTABLE_LEVEL;
 	int ret;
 
-	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
-	if (!domain)
-		return NULL;
-
 	/*
 	 * Force IOMMU v1 page table when iommu=pt and
 	 * when allocating domain for pass-through devices.
@@ -2097,6 +2093,10 @@ static struct protection_domain *protection_domain_alloc(unsigned int type)
 		return NULL;
 	}
 
+	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+	if (!domain)
+		return NULL;
+
 	switch (pgtable) {
 	case AMD_IOMMU_V1:
 		ret = protection_domain_init_v1(domain, mode);