[PATCH V2 20/22] cpr: only-cpr-capable option

[Steve Sistare]

Add the only-cpr-capable option, which causes qemu to exit with an error
if any devices that are not capable of cpr are added.  This guarantees that
a cprsave operation will not fail with an unsupported device error.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 chardev/char-socket.c   |  1 +
 exec.c                  |  3 +++
 include/sysemu/sysemu.h |  1 +
 migration/migration.c   |  6 ++++++
 qemu-options.hx         |  8 ++++++++
 softmmu/vl.c            | 13 +++++++++++++
 6 files changed, 32 insertions(+)

diff --git a/chardev/char-socket.c b/chardev/char-socket.c
index 0965305..580d731 100644
--- a/chardev/char-socket.c
+++ b/chardev/char-socket.c
@@ -36,6 +36,7 @@
 #include "qapi/qapi-visit-sockets.h"
 
 #include "chardev/char-io.h"
+#include "sysemu/sysemu.h"
 #include "qemu/env.h"
 
 /***********************************************************/
diff --git a/exec.c b/exec.c
index 6a6e43d..01732f5 100644
--- a/exec.c
+++ b/exec.c
@@ -2271,6 +2271,9 @@ static void ram_block_add(RAMBlock *new_block, Error 
**errp, bool shared)
                 new_block->flags |= RAM_SHARED;
                 addr = file_ram_alloc(new_block, maxlen, mfd, false, errp);
                 trace_anon_memfd_alloc(name, maxlen, addr, mfd);
+            } else if (only_cpr_capable) {
+                error_report("only-cpr-capable requires memfd-alloc");
+                errno = 0;
             } else {
                 addr = phys_mem_alloc(maxlen, &mr->align, shared);
             }
diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index f0017d4..a72e7da 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -14,6 +14,7 @@ extern const char *qemu_name;
 extern QemuUUID qemu_uuid;
 extern bool qemu_uuid_set;
 extern bool memfd_alloc;
+extern bool only_cpr_capable;
 extern int start_on_wake;
 
 void qemu_add_data_dir(const char *path);
diff --git a/migration/migration.c b/migration/migration.c
index 8fe3633..5459a2a 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -1099,6 +1099,12 @@ static bool migrate_caps_check(bool *cap_list,
         }
     }
 
+    if (cap_list[MIGRATION_CAPABILITY_X_COLO] && only_cpr_capable) {
+        error_setg(errp, "x-colo is not compatible with -only-cpr-capable");
+        return false;
+    }
+
+
     return true;
 }
 
diff --git a/qemu-options.hx b/qemu-options.hx
index 1ab5af5..ff8464f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4116,6 +4116,14 @@ SRST
     an unmigratable state.
 ERST
 
+DEF("only-cpr-capable", 0, QEMU_OPTION_only_cpr_capable, \
+    "-only-cpr-capable    allow only cpr capable devices\n", QEMU_ARCH_ALL)
+SRST
+``-only-cpr-capable``
+    Only allow cpr capable devices, which guarantees that cprsave will not fail
+    with an unsupported device error.
+ERST
+
 #ifdef __linux__
 DEF("memfd-alloc", 0,  QEMU_OPTION_memfd_alloc, \
     "-memfd-alloc         allocate anonymous memory using memfd_create\n",
diff --git a/softmmu/vl.c b/softmmu/vl.c
index 9f2be5c..e101056 100644
--- a/softmmu/vl.c
+++ b/softmmu/vl.c
@@ -164,6 +164,7 @@ bool boot_strict;
 uint8_t *boot_splash_filedata;
 int only_migratable; /* turn it off unless user states otherwise */
 bool wakeup_suspend_enabled;
+bool only_cpr_capable;
 bool memfd_alloc;
 int start_on_wake;
 static char **argv_main;
@@ -3679,6 +3680,9 @@ void qemu_init(int argc, char **argv, char **envp)
             case QEMU_OPTION_only_migratable:
                 only_migratable = 1;
                 break;
+            case QEMU_OPTION_only_cpr_capable:
+                only_cpr_capable = true;
+                break;
             case QEMU_OPTION_memfd_alloc:
                 memfd_alloc = true;
                 break;
@@ -4433,6 +4437,15 @@ void qemu_init(int argc, char **argv, char **envp)
 
     cpu_synchronize_all_post_init();
 
+    if (only_cpr_capable && replay_mode != REPLAY_MODE_NONE) {
+        error_report("replay is not compatible with -only-cpr-capable");
+        exit(1);
+    }
+    if (only_cpr_capable && !qemu_chr_cpr_capable(&err)) {
+        error_report_err(err);
+        exit(1);
+    }
+
     rom_reset_order_override();
 
     /* Did we create any drives that we failed to create a device for? */
-- 
1.8.3.1