spapr: Fix 2.7<->2.8 migration of PCI host bridge

daa2369 "spapr_pci: Add a 64-bit MMIO window" subtly broke migration
from qemu-2.7 to the current version.  It split the device's MMIO
window into two pieces for 32-bit and 64-bit MMIO.

The patch included backwards compatibility code to convert the old
property into the new format.  However, the property value was also
transferred in the migration stream and compared with a (probably
unwise) VMSTATE_EQUAL.  So, the "raw" value from 2.7 is compared to
the new style converted value from (pre-)2.8 giving a mismatch and
migration failure.

Along with the actual field that caused the breakage, there are
several other ill-advised VMSTATE_EQUAL()s.  To fix forwards
migration, we read the values in the stream into scratch variables and
ignore them, instead of comparing for equality.  To fix backwards
migration, we populate those scratch variables in pre_save() with
adjusted values to match the old behaviour.

To permit the eventual possibility of removing this cruft from the
stream, we only include these compatibility fields if a new
'pre-2.8-migration' property is set.  We clear it on the pseries-2.8
machine type, which obviously can't be migrated backwards, but set it
on earlier machine type versions.

Signed-off-by: David Gibson <[email protected]>
Reviewed-by: Dr. David Alan Gilbert <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Reviewed-by: Greg Kurz <[email protected]>
Reviewed-by: Alexey Kardashevskiy <[email protected]>

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 775ad2e1d9c042659240d573e5c60bb46539518e..c3269c7f50bbc20f2abbdec3532560253df8282a 100644 (file)
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2772,6 +2772,11 @@ DEFINE_SPAPR_MACHINE(2_8, "2.8", true);
         .driver = TYPE_POWERPC_CPU,                 \
         .property = "pre-2.8-migration",            \
         .value    = "on",                           \
+    },                                              \
+    {                                               \
+        .driver = TYPE_SPAPR_PCI_HOST_BRIDGE,       \
+        .property = "pre-2.8-migration",            \
+        .value    = "on",                           \
     },
 
 static void phb_placement_2_7(sPAPRMachineState *spapr, uint32_t index,

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 7cde30ee09fb22b8147b3a54d2431768a267fbd0..fd6fc1d9534459a151fd33b383e3baa4f06a1888 100644 (file)
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1590,6 +1590,8 @@ static Property spapr_phb_properties[] = {
     DEFINE_PROP_UINT64("pgsz", sPAPRPHBState, page_size_mask,
                        (1ULL << 12) | (1ULL << 16)),
     DEFINE_PROP_UINT32("numa_node", sPAPRPHBState, numa_node, -1),
+    DEFINE_PROP_BOOL("pre-2.8-migration", sPAPRPHBState,
+                     pre_2_8_migration, false),
     DEFINE_PROP_END_OF_LIST(),
 };
 
@@ -1636,6 +1638,20 @@ static void spapr_pci_pre_save(void *opaque)
         sphb->msi_devs[i].key = *(uint32_t *) key;
         sphb->msi_devs[i].value = *(spapr_pci_msi *) value;
     }
+
+    if (sphb->pre_2_8_migration) {
+        sphb->mig_liobn = sphb->dma_liobn[0];
+        sphb->mig_mem_win_addr = sphb->mem_win_addr;
+        sphb->mig_mem_win_size = sphb->mem_win_size;
+        sphb->mig_io_win_addr = sphb->io_win_addr;
+        sphb->mig_io_win_size = sphb->io_win_size;
+
+        if ((sphb->mem64_win_size != 0)
+            && (sphb->mem64_win_addr
+                == (sphb->mem_win_addr + sphb->mem_win_size))) {
+            sphb->mig_mem_win_size += sphb->mem64_win_size;
+        }
+    }
 }
 
 static int spapr_pci_post_load(void *opaque, int version_id)
@@ -1658,6 +1674,13 @@ static int spapr_pci_post_load(void *opaque, int version_id)
     return 0;
 }
 
+static bool pre_2_8_migration(void *opaque, int version_id)
+{
+    sPAPRPHBState *sphb = opaque;
+
+    return sphb->pre_2_8_migration;
+}
+
 static const VMStateDescription vmstate_spapr_pci = {
     .name = "spapr_pci",
     .version_id = 2,
@@ -1666,11 +1689,11 @@ static const VMStateDescription vmstate_spapr_pci = {
     .post_load = spapr_pci_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT64_EQUAL(buid, sPAPRPHBState),
-        VMSTATE_UINT32_EQUAL(dma_liobn[0], sPAPRPHBState),
-        VMSTATE_UINT64_EQUAL(mem_win_addr, sPAPRPHBState),
-        VMSTATE_UINT64_EQUAL(mem_win_size, sPAPRPHBState),
-        VMSTATE_UINT64_EQUAL(io_win_addr, sPAPRPHBState),
-        VMSTATE_UINT64_EQUAL(io_win_size, sPAPRPHBState),
+        VMSTATE_UINT32_TEST(mig_liobn, sPAPRPHBState, pre_2_8_migration),
+        VMSTATE_UINT64_TEST(mig_mem_win_addr, sPAPRPHBState, pre_2_8_migration),
+        VMSTATE_UINT64_TEST(mig_mem_win_size, sPAPRPHBState, pre_2_8_migration),
+        VMSTATE_UINT64_TEST(mig_io_win_addr, sPAPRPHBState, pre_2_8_migration),
+        VMSTATE_UINT64_TEST(mig_io_win_size, sPAPRPHBState, pre_2_8_migration),
         VMSTATE_STRUCT_ARRAY(lsi_table, sPAPRPHBState, PCI_NUM_PINS, 0,
                              vmstate_spapr_pci_lsi, struct spapr_pci_lsi),
         VMSTATE_INT32(msi_devs_num, sPAPRPHBState),

diff --git a/include/hw/pci-host/spapr.h b/include/hw/pci-host/spapr.h
index b92c1b59f14442ad2f9273467f313eda740fc486..092294ed5a6536327f5a9d1a88c7b2492dc36d0a 100644 (file)
--- a/include/hw/pci-host/spapr.h
+++ b/include/hw/pci-host/spapr.h
@@ -79,6 +79,12 @@ struct sPAPRPHBState {
     uint64_t dma64_win_addr;
 
     uint32_t numa_node;
+
+    /* Fields for migration compatibility hacks */
+    bool pre_2_8_migration;
+    uint32_t mig_liobn;
+    hwaddr mig_mem_win_addr, mig_mem_win_size;
+    hwaddr mig_io_win_addr, mig_io_win_size;
 };
 
 #define SPAPR_PCI_MEM_WIN_BUS_OFFSET 0x80000000ULL