s390/uv: de-duplicate checks for Protected Host Virtualization

De-duplicate checks for Protected Host Virtualization in decompressor and
kernel.

Set prot_virt_host=0 in the decompressor in *any* of the following cases
and hand it over to the decompressed kernel:
* No explicit prot_virt=1 is given on the kernel command-line
* Protected Guest Virtualization is enabled
* Hardware support not present
* kdump or stand-alone dump

The decompressed kernel needs to use only is_prot_virt_host() instead of
performing again all checks done by the decompressor.
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/boot/uv.c

@@ -51,32 +51,34 @@ void uv_query_info(void)
 }
 
 #if IS_ENABLED(CONFIG_KVM)
-static bool has_uv_sec_stor_limit(void)
+void adjust_to_uv_max(unsigned long *vmax)
 {
-	/*
-	 * keep these conditions in line with setup_uv()
-	 */
-	if (!is_prot_virt_host())
-		return false;
-
-	if (is_prot_virt_guest())
-		return false;
-
-	if (!test_facility(158))
-		return false;
-
-	return !!uv_info.max_sec_stor_addr;
+	if (is_prot_virt_host() && uv_info.max_sec_stor_addr)
+		*vmax = min_t(unsigned long, *vmax, uv_info.max_sec_stor_addr);
 }
 
-void adjust_to_uv_max(unsigned long *vmax)
+static int is_prot_virt_host_capable(void)
 {
-	if (has_uv_sec_stor_limit())
-		*vmax = min_t(unsigned long, *vmax, uv_info.max_sec_stor_addr);
+	/* disable if no prot_virt=1 given on command-line */
+	if (!is_prot_virt_host())
+		return 0;
+	/* disable if protected guest virtualization is enabled */
+	if (is_prot_virt_guest())
+		return 0;
+	/* disable if no hardware support */
+	if (!test_facility(158))
+		return 0;
+	/* disable if kdump */
+	if (OLDMEM_BASE)
+		return 0;
+	/* disable if stand-alone dump */
+	if (ipl_block_valid && is_ipl_block_dump())
+		return 0;
+	return 1;
 }
 
 void sanitize_prot_virt_host(void)
 {
-	if (OLDMEM_BASE || (ipl_block_valid && is_ipl_block_dump()))
-		prot_virt_host = 0;
+	prot_virt_host = is_prot_virt_host_capable();
 }
 #endif

arch/s390/kernel/uv.c

@@ -51,24 +51,9 @@ void __init setup_uv(void)
 {
 	unsigned long uv_stor_base;
 
-	/*
-	 * keep these conditions in line with has_uv_sec_stor_limit()
-	 */
 	if (!is_prot_virt_host())
 		return;
 
-	if (is_prot_virt_guest()) {
-		prot_virt_host = 0;
-		pr_warn("Protected virtualization not available in protected guests.");
-		return;
-	}
-
-	if (!test_facility(158)) {
-		prot_virt_host = 0;
-		pr_warn("Protected virtualization not supported by the hardware.");
-		return;
-	}
-
 	uv_stor_base = (unsigned long)memblock_alloc_try_nid(
 		uv_info.uv_base_stor_len, SZ_1M, SZ_2G,
 		MEMBLOCK_ALLOC_ACCESSIBLE, NUMA_NO_NODE);