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Re: [Qemu-devel] [PATCH] acpi: Use apic_id_limit when calculating legacy
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-devel] [PATCH] acpi: Use apic_id_limit when calculating legacy ACPI table size |
Date: |
Fri, 12 Dec 2014 17:50:37 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.3.0 |
On 12/12/2014 17:38, Eduardo Habkost wrote:
> The code that calculates the legacy ACPI table size for migration
> compatibility uses max_cpus when calculating legacy_aml_len (the size of
> the DSDT and SSDT tables). However, the SSDT grows according to APIC ID
> limit, not max_cpus.
>
> The bug is not triggered very often because of the 4k alignment on the
> table size. But it can be triggered if you are unlucky enough to cross a
> 4k boundary. For example, using the following:
>
> $ qemu-system-x86_64 -machine pc-i440fx-2.0 -smp
> 99,sockets=3,cores=33,threads=1
> qemu-system-x86_64: Warning: migration may not work.
>
> Change the legacy_aml_len calculation to use apic_id_limit, to calculate
> the right size.
>
> Signed-off-by: Eduardo Habkost <address@hidden>
> ---
> hw/i386/acpi-build.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a4d0c0c..359fb43 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1675,7 +1675,7 @@ void acpi_build(PcGuestInfo *guest_info,
> AcpiBuildTables *tables)
> */
> int legacy_aml_len =
> guest_info->legacy_acpi_table_size +
> - ACPI_BUILD_LEGACY_CPU_AML_SIZE * max_cpus;
> + ACPI_BUILD_LEGACY_CPU_AML_SIZE * guest_info->apic_id_limit;
> int legacy_table_size =
> ROUND_UP(tables->table_data->len - aml_len + legacy_aml_len,
> ACPI_BUILD_ALIGN_SIZE);
>
Reviewed-by: Paolo Bonzini <address@hidden>