On Wed, Aug 3, 2022 at 3:00 PM Michael S. Tsirkin <
mst@redhat.com> wrote:
On Thu, Jul 28, 2022 at 07:50:34AM -0400, Igor Mammedov wrote:
> QEMU crashes trying to save VMSTATE when only MIPS target are compiled in
> $ qemu-system-mips -monitor stdio
> (qemu) migrate "exec:gzip -c > STATEFILE.gz"
> Segmentation fault (core dumped)
>
> It happens due to PIIX4_PM trying to parse hotplug vmstate structures
> which are valid only for x86 and not for MIPS (as it requires ACPI
> tables support which is not existent for ithe later)
>
> Issue was probably exposed by trying to cleanup/compile out unused
> ACPI bits from MIPS target (but forgetting about migration bits).
>
> Disable compiled out features using compat properties as the least
> risky way to deal with issue.
>
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
For 7.1 this seems like the lesser evil.
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Yes for 7.1, let's go ahead with this aa it seems least risky approach.
I've already reviewed it.
> ---
> PS:
> another approach could be setting defaults to disabled state and
> enabling them using compat props on PC machines (which is more
> code to deal with => more risky) or continue with PIIX4_PM
> refactoring to split x86-shism out (which I'm not really
> interested in due to risk of regressions for not much of
> benefit)
> ---
> hw/mips/malta.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/hw/mips/malta.c b/hw/mips/malta.c
> index 7a0ec513b0..0e932988e0 100644
> --- a/hw/mips/malta.c
> +++ b/hw/mips/malta.c
> @@ -1442,6 +1442,14 @@ static const TypeInfo mips_malta_device = {
> .instance_init = mips_malta_instance_init,
> };
>
> +GlobalProperty malta_compat[] = {
> + { "PIIX4_PM", "memory-hotplug-support", "off" },
> + { "PIIX4_PM", "acpi-pci-hotplug-with-bridge-support", "off" },
> + { "PIIX4_PM", "acpi-root-pci-hotplug", "off" },
> + { "PIIX4_PM", "x-not-migrate-acpi-index", "true" },
> +};
> +const size_t malta_compat_len = G_N_ELEMENTS(malta_compat);
> +
> static void mips_malta_machine_init(MachineClass *mc)
> {
> mc->desc = "MIPS Malta Core LV";
> @@ -1455,6 +1463,7 @@ static void mips_malta_machine_init(MachineClass *mc)
> mc->default_cpu_type = MIPS_CPU_TYPE_NAME("24Kf");
> #endif
> mc->default_ram_id = "mips_malta.ram";
> + compat_props_add(mc->compat_props, malta_compat, malta_compat_len);
> }
>
> DEFINE_MACHINE("malta", mips_malta_machine_init)
> --
> 2.31.1