iommu/amd: Fix failure return from snp_lookup_rmpentry()

Commit

  f366a8d: ("iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown")

leads to the following Smatch static checker warning:

  drivers/iommu/amd/init.c:3820 iommu_page_make_shared() error: uninitialized symbol 'assigned'.

Fix it.

  [ bp: Address the other error cases too. ]

Fixes: f366a8d ("iommu/amd: Clean up RMP entries for IOMMU pages during SNP shutdown")
Closes: https://lore.kernel.org/linux-iommu/1be69f6a-e7e1-45f9-9a74-b2550344f3fd@moroto.mountain
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Joerg Roedel <jroedel@suse.com>
Link: https://lore.kernel.org/lkml/20240126041126.1927228-20-michael.roth@amd.com

drivers/iommu/amd/init.c

@@ -3813,23 +3813,28 @@ static int iommu_page_make_shared(void *page)
 		bool assigned;
 
 		ret = snp_lookup_rmpentry(pfn, &assigned, &level);
-		if (ret)
-			pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n",
-				pfn, ret);
+		if (ret) {
+			pr_warn("IOMMU PFN %lx RMP lookup failed, ret %d\n", pfn, ret);
+			return ret;
+		}
 
-		if (!assigned)
-			pr_warn("IOMMU PFN %lx not assigned in RMP table\n",
-				pfn);
+		if (!assigned) {
+			pr_warn("IOMMU PFN %lx not assigned in RMP table\n", pfn);
+			return -EINVAL;
+		}
 
 		if (level > PG_LEVEL_4K) {
 			ret = psmash(pfn);
-			if (ret) {
-				pr_warn("IOMMU PFN %lx had a huge RMP entry, but attempted psmash failed, ret: %d, level: %d\n",
-					pfn, ret, level);
-			}
+			if (!ret)
+				goto done;
+
+			pr_warn("PSMASH failed for IOMMU PFN %lx huge RMP entry, ret: %d, level: %d\n",
+				pfn, ret, level);
+			return ret;
 		}
 	}
 
+done:
 	return rmp_make_shared(pfn, PG_LEVEL_4K);
 }