On Thu, Dec 14, 2017 at 07:09:48PM +0100, Laurent Vivier wrote: > 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 <lviv...@redhat.com>
Applied to ppc-for-2.12.
> ---
> hw/ppc/spapr.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 1ac7eb0f8c..66d0ed5256 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1440,7 +1440,10 @@ static void ppc_spapr_reset(void)
> /* 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. */
> @@ -1499,7 +1502,6 @@ static void ppc_spapr_reset(void)
> 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;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature
