[PATCH v12 22/35] pc-bios/s390-ccw: Introduce ZiplBootMode enum for IPL mode selection

[Zhuoying Cai <zycai@linux.ibm.com>]

Add ZiplBootMode enumeration to support multiple IPL boot configurations.
Boot modes differentiate between normal boot and secure IPL operations,
enabled based on boot certificates specified via the boot-certs option.

Normal Mode: IPL when no certificates are provided. No signature
verification is performed.

This prepares for future secure IPL modes requiring signature
verification.

Signed-off-by: Zhuoying Cai <zycai@linux.ibm.com>
Reviewed-by: Collin Walling <walling@linux.ibm.com>
---
 docs/system/s390x/secure-ipl.rst | 21 +++++++++++++++++++++
 pc-bios/s390-ccw/bootmap.c       | 16 +++++++++++++++-
 pc-bios/s390-ccw/main.c          |  6 ++++++
 pc-bios/s390-ccw/s390-ccw.h      |  6 ++++++
 4 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/docs/system/s390x/secure-ipl.rst b/docs/system/s390x/secure-ipl.rst
index 88df52ce2f..9d7d33f5ed 100644
--- a/docs/system/s390x/secure-ipl.rst
+++ b/docs/system/s390x/secure-ipl.rst
@@ -18,3 +18,24 @@ Note: certificate files must have a .pem extension.
 .. code-block:: shell
 
     qemu-system-s390x -machine s390-ccw-virtio,boot-certs.0.path=/.../qemu/certs,boot-certs.1.path=/another/path/cert.pem ...
+
+
+IPL Modes
+---------
+
+Multiple IPL modes are available to differentiate between the various IPL
+configurations. These modes are mutually exclusive and enabled based on the
+``boot-certs`` option on the QEMU command line.
+
+Normal Mode
+^^^^^^^^^^^
+
+The absence of certificates will attempt to IPL a guest without secure IPL
+operations. No checks are performed, and no warnings/errors are reported.
+This is the default mode.
+
+Configuration:
+
+.. code-block:: shell
+
+    qemu-system-s390x -machine s390-ccw-virtio ...
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index b19981feb1..667a69f80d 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -733,7 +733,14 @@ static int zipl_run(ScsiBlockPtr *pte)
     /* Load image(s) into RAM */
     entry = (ComponentEntry *)(&header[1]);
 
-    rc = zipl_run_normal(&entry, tmp_sec);
+    switch (boot_mode) {
+    case ZIPL_BOOT_MODE_NORMAL:
+        rc = zipl_run_normal(&entry, tmp_sec);
+        break;
+    default:
+        panic("Unknown boot mode");
+    }
+
     if (rc) {
         return rc;
     }
@@ -1105,12 +1112,16 @@ void zipl_load(void)
     VDev *vdev = virtio_get_device();
 
     if (vdev->is_cdrom) {
+        IPL_assert((boot_mode == ZIPL_BOOT_MODE_NORMAL),
+                   "Secure boot from ISO image is not supported!");
         ipl_iso_el_torito();
         puts("Failed to IPL this ISO image!");
         return;
     }
 
     if (virtio_get_device_type() == VIRTIO_ID_NET) {
+        IPL_assert((boot_mode == ZIPL_BOOT_MODE_NORMAL),
+                    "Virtio net boot device does not support secure boot!");
         netmain();
         puts("Failed to IPL from this network!");
         return;
@@ -1121,6 +1132,9 @@ void zipl_load(void)
         return;
     }
 
+    IPL_assert((boot_mode == ZIPL_BOOT_MODE_NORMAL),
+                "Secure boot with the ECKD scheme is not supported!");
+
     switch (virtio_get_device_type()) {
     case VIRTIO_ID_BLOCK:
         zipl_load_vblk();
diff --git a/pc-bios/s390-ccw/main.c b/pc-bios/s390-ccw/main.c
index b8f836c682..cd3d0776b0 100644
--- a/pc-bios/s390-ccw/main.c
+++ b/pc-bios/s390-ccw/main.c
@@ -30,6 +30,7 @@ IplParameterBlock *iplb;
 bool have_iplb;
 static uint16_t cutype;
 LowCore *lowcore; /* Yes, this *is* a pointer to address 0 */
+ZiplBootMode boot_mode;
 
 #define LOADPARM_PROMPT "PROMPT  "
 #define LOADPARM_EMPTY  "        "
@@ -303,6 +304,9 @@ static void ipl_ccw_device(void)
     switch (cutype) {
     case CU_TYPE_DASD_3990:
     case CU_TYPE_DASD_2107:
+        IPL_assert((boot_mode == ZIPL_BOOT_MODE_NORMAL),
+                    "Passthrough (vfio) CCW device does not support secure boot!");
+
         dasd_ipl(blk_schid, cutype);
         break;
     case CU_TYPE_VIRTIO:
@@ -390,6 +394,8 @@ void main(void)
         probe_boot_device();
     }
 
+    boot_mode = ZIPL_BOOT_MODE_NORMAL;
+
     while (have_iplb) {
         boot_setup();
         if (have_iplb && find_boot_device()) {
diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index 1e1f71775e..5420443ad2 100644
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -69,6 +69,12 @@ int sclp_read(char *str, size_t count);
 /* bootmap.c */
 void zipl_load(void);
 
+typedef enum ZiplBootMode {
+    ZIPL_BOOT_MODE_NORMAL = 0,
+} ZiplBootMode;
+
+extern ZiplBootMode boot_mode;
+
 /* jump2ipl.c */
 void write_reset_psw(uint64_t psw);
 int jump_to_IPL_code(uint64_t address);
-- 
2.54.0