spapr: don't initialize PATB entry if max-cpu-compat < power9
if KVM is enabled and KVM capabilities MMU radix is available,
the partition table entry (patb_entry) for the radix mode is
initialized by default in ppc_spapr_reset().
It's a problem if we want to migrate the guest to a POWER8 host
while the kernel is not started to set the value to the one
expected for a POWER8 CPU.
The "-machine max-cpu-compat=power8" should allow to migrate
a POWER9 KVM host to a POWER8 KVM host, but because patb_entry
is set, the destination QEMU tries to enable radix mode on the
POWER8 host. This fails and cancels the migration:
Process table config unsupported by the host
error while loading state for instance 0x0 of device 'spapr'
load of migration failed: Invalid argument
This patch doesn't set the PATB entry if the user provides
a CPU compatibility mode that doesn't support radix mode.
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
(cherry picked from commit 1481fe5fcfeb7fcf3c1ebb9d8c0432e3e0188ccf)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 48199be..25768e2 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1421,7 +1421,10 @@
/* Check for unknown sysbus devices */
foreach_dynamic_sysbus_device(find_unknown_sysbus_device, NULL);
- if (kvm_enabled() && kvmppc_has_cap_mmu_radix()) {
+ first_ppc_cpu = POWERPC_CPU(first_cpu);
+ if (kvm_enabled() && kvmppc_has_cap_mmu_radix() &&
+ ppc_check_compat(first_ppc_cpu, CPU_POWERPC_LOGICAL_3_00, 0,
+ spapr->max_compat_pvr)) {
/* If using KVM with radix mode available, VCPUs can be started
* without a HPT because KVM will start them in radix mode.
* Set the GR bit in PATB so that we know there is no HPT. */
@@ -1480,7 +1483,6 @@
g_free(fdt);
/* Set up the entry state */
- first_ppc_cpu = POWERPC_CPU(first_cpu);
first_ppc_cpu->env.gpr[3] = fdt_addr;
first_ppc_cpu->env.gpr[5] = 0;
first_cpu->halted = 0;
