| Message ID | 1418402316-31738-1-git-send-email-ehabkost@redhat.com |
|---|---|
| State | New |
| Headers | show |
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 <ehabkost@redhat.com> > --- > 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 <pbonzini@redhat.com>
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);
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 <ehabkost@redhat.com> --- hw/i386/acpi-build.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)