kexec: implement STATUS hypercall to check if image is loaded

The tools that use kexec are asynchronous in nature and do not keep
state changes. As such provide an hypercall to find out whether an
image has been loaded for either type.

Note: No need to modify XSM as it has one size fits all check and
does not check for subcommands.

Note: No need to check KEXEC_FLAG_IN_PROGRESS (and error out of
kexec_status()) as this flag is set only once by the first/only
cpu on the crash path.

Note: This is just the Xen side of the hypercall, kexec-tools patch
to come separately.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 4ab0f571179f82bca639e45510614dea5c03442a..63c616ff6a17cb3b7a5cd3eb79c8553358f6be8d 100644 (file)
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2574,6 +2574,16 @@ int xc_kexec_load(xc_interface *xch, uint8_t type, uint16_t arch,
  */
 int xc_kexec_unload(xc_interface *xch, int type);
 
+/*
+ * Find out whether the image has been succesfully loaded.
+ *
+ * The type can be either KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH.
+ * If zero is returned, that means no image is loaded for the type.
+ * If one is returned, that means an image is loaded for the type.
+ * Otherwise, negative return value indicates error.
+ */
+int xc_kexec_status(xc_interface *xch, int type);
+
 typedef xenpf_resource_entry_t xc_resource_entry_t;
 
 /*

diff --git a/tools/libxc/xc_kexec.c b/tools/libxc/xc_kexec.c
index 59e2f076f42fac35cce46a0da744e431d88f427f..a4e8966adc322ff486ca837b76f1cdffe31c3d3c 100644 (file)
--- a/tools/libxc/xc_kexec.c
+++ b/tools/libxc/xc_kexec.c
@@ -126,3 +126,27 @@ out:
 
     return ret;
 }
+
+int xc_kexec_status(xc_interface *xch, int type)
+{
+    DECLARE_HYPERCALL_BUFFER(xen_kexec_status_t, status);
+    int ret = -1;
+
+    status = xc_hypercall_buffer_alloc(xch, status, sizeof(*status));
+    if ( status == NULL )
+    {
+        PERROR("Could not alloc buffer for kexec status hypercall");
+        goto out;
+    }
+
+    status->type = type;
+
+    ret = xencall2(xch->xcall, __HYPERVISOR_kexec_op,
+                   KEXEC_CMD_kexec_status,
+                   HYPERCALL_BUFFER_AS_ARG(status));
+
+out:
+    xc_hypercall_buffer_free(xch, status);
+
+    return ret;
+}

diff --git a/xen/common/kexec.c b/xen/common/kexec.c
index c83d48fc79db6745bbf99ffafcbef4536f1be46c..aa808cb2f2c4256dc99041d427c5a26371e4a855 100644 (file)
--- a/xen/common/kexec.c
+++ b/xen/common/kexec.c
@@ -1169,6 +1169,22 @@ static int kexec_unload(XEN_GUEST_HANDLE_PARAM(void) uarg)
     return kexec_do_unload(&unload);
 }
 
+static int kexec_status(XEN_GUEST_HANDLE_PARAM(void) uarg)
+{
+    xen_kexec_status_t status;
+    int base, bit;
+
+    if ( unlikely(copy_from_guest(&status, uarg, 1)) )
+        return -EFAULT;
+
+    /* No need to check KEXEC_FLAG_IN_PROGRESS. */
+
+    if ( kexec_load_get_bits(status.type, &base, &bit) )
+        return -EINVAL;
+
+    return test_bit(bit, &kexec_flags);
+}
+
 static int do_kexec_op_internal(unsigned long op,
                                 XEN_GUEST_HANDLE_PARAM(void) uarg,
                                 bool_t compat)
@@ -1208,6 +1224,9 @@ static int do_kexec_op_internal(unsigned long op,
     case KEXEC_CMD_kexec_unload:
         ret = kexec_unload(uarg);
         break;
+    case KEXEC_CMD_kexec_status:
+        ret = kexec_status(uarg);
+        break;
     }
 
     return ret;

diff --git a/xen/include/public/kexec.h b/xen/include/public/kexec.h
index a6a0a88f4fb2075e391abeeffdc0ce5abdca7970..c200e8ceee24e5978950b319e7dcd6b97fc97410 100644 (file)
--- a/xen/include/public/kexec.h
+++ b/xen/include/public/kexec.h
@@ -227,6 +227,19 @@ typedef struct xen_kexec_unload {
 } xen_kexec_unload_t;
 DEFINE_XEN_GUEST_HANDLE(xen_kexec_unload_t);
 
+/*
+ * Figure out whether we have an image loaded. A return value of
+ * zero indicates no image loaded. A return value of one
+ * indicates an image is loaded. A negative return value
+ * indicates an error.
+ *
+ * Type must be one of KEXEC_TYPE_DEFAULT or KEXEC_TYPE_CRASH.
+ */
+#define KEXEC_CMD_kexec_status 6
+typedef struct xen_kexec_status {
+    uint8_t type;
+} xen_kexec_status_t;
+DEFINE_XEN_GUEST_HANDLE(xen_kexec_status_t);
 #else /* __XEN_INTERFACE_VERSION__ < 0x00040400 */
 
 #define KEXEC_CMD_kexec_load KEXEC_CMD_kexec_load_v1