spapr: Validate capabilities on migration

Now that the "pseries" machine type implements optional capabilities (well,
one so far) there's the possibility of having different capabilities
available at either end of a migration.  Although arguably a user error,
it would be nice to catch this situation and fail as gracefully as we can.

This adds code to migrate the capabilities flags.  These aren't pulled
directly into the destination's configuration since what the user has
specified on the destination command line should take precedence.  However,
they are checked against the destination capabilities.

If the source was using a capability which is absent on the destination,
we fail the migration, since that could easily cause a guest crash or other
bad behaviour.  If the source lacked a capability which is present on the
destination we warn, but allow the migration to proceed.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>

1 files changed, 6 insertions, 0 deletions

diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index dc64f4ebcb..5c85f39c3b 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -54,6 +54,8 @@ typedef enum {
  * Capabilities
  */
 
+/* These bits go in the migration stream, so they can't be reassigned */
+
 /* Hardware Transactional Memory */
 #define SPAPR_CAP_HTM               0x0000000000000001ULL
 
@@ -142,6 +144,7 @@ struct sPAPRMachineState {
     const char *icp_type;
 
     sPAPRCapabilities forced_caps, forbidden_caps;
+    sPAPRCapabilities mig_forced_caps, mig_forbidden_caps;
     sPAPRCapabilities effective_caps;
 };
 
@@ -743,6 +746,8 @@ qemu_irq spapr_qirq(sPAPRMachineState *spapr, int irq);
 /*
  * Handling of optional capabilities
  */
+extern const VMStateDescription vmstate_spapr_caps;
+
 static inline sPAPRCapabilities spapr_caps(uint64_t mask)
 {
     sPAPRCapabilities caps = { mask };
@@ -757,5 +762,6 @@ static inline bool spapr_has_cap(sPAPRMachineState *spapr, uint64_t cap)
 void spapr_caps_reset(sPAPRMachineState *spapr);
 void spapr_caps_validate(sPAPRMachineState *spapr, Error **errp);
 void spapr_caps_add_properties(sPAPRMachineClass *smc, Error **errp);
+int spapr_caps_post_migration(sPAPRMachineState *spapr);
 
 #endif /* HW_SPAPR_H */