diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c index ebc5f034e3..d90c471792 100644 --- a/hw/i386/acpi-build.c +++ b/hw/i386/acpi-build.c @@ -25,7 +25,9 @@ #include #include "qemu-common.h" #include "qemu/bitmap.h" +#include "qemu/osdep.h" #include "qemu/range.h" +#include "qemu/error-report.h" #include "hw/pci/pci.h" #include "qom/cpu.h" #include "hw/i386/pc.h" @@ -52,6 +54,14 @@ #include "qapi/qmp/qint.h" #include "qom/qom-qobject.h" +/* These are used to size the ACPI tables for -M pc-i440fx-1.7 and + * -M pc-i440fx-2.0. Even if the actual amount of AML generated grows + * a little bit, there should be plenty of free space since the DSDT + * shrunk by ~1.5k between QEMU 2.0 and QEMU 2.1. + */ +#define ACPI_BUILD_LEGACY_CPU_AML_SIZE 97 +#define ACPI_BUILD_ALIGN_SIZE 0x1000 + typedef struct AcpiCpuInfo { DECLARE_BITMAP(found_cpus, ACPI_CPU_HOTPLUG_ID_LIMIT); } AcpiCpuInfo; @@ -1440,13 +1450,14 @@ static void acpi_build(PcGuestInfo *guest_info, AcpiBuildTables *tables) { GArray *table_offsets; - unsigned facs, dsdt, rsdt; + unsigned facs, ssdt, dsdt, rsdt; AcpiCpuInfo cpu; AcpiPmInfo pm; AcpiMiscInfo misc; AcpiMcfgInfo mcfg; PcPciInfo pci; uint8_t *u; + size_t aml_len = 0; acpi_get_cpu_info(&cpu); acpi_get_pm_info(&pm); @@ -1474,13 +1485,20 @@ void acpi_build(PcGuestInfo *guest_info, AcpiBuildTables *tables) dsdt = tables->table_data->len; build_dsdt(tables->table_data, tables->linker, &misc); + /* Count the size of the DSDT and SSDT, we will need it for legacy + * sizing of ACPI tables. + */ + aml_len += tables->table_data->len - dsdt; + /* ACPI tables pointed to by RSDT */ acpi_add_table(table_offsets, tables->table_data); build_fadt(tables->table_data, tables->linker, &pm, facs, dsdt); + ssdt = tables->table_data->len; acpi_add_table(table_offsets, tables->table_data); build_ssdt(tables->table_data, tables->linker, &cpu, &pm, &misc, &pci, guest_info); + aml_len += tables->table_data->len - ssdt; acpi_add_table(table_offsets, tables->table_data); build_madt(tables->table_data, tables->linker, &cpu, guest_info); @@ -1513,14 +1531,45 @@ void acpi_build(PcGuestInfo *guest_info, AcpiBuildTables *tables) /* RSDP is in FSEG memory, so allocate it separately */ build_rsdp(tables->rsdp, tables->linker, rsdt); - /* We'll expose it all to Guest so align size to reduce + /* We'll expose it all to Guest so we want to reduce * chance of size changes. * RSDP is small so it's easy to keep it immutable, no need to * bother with alignment. + * + * We used to align the tables to 4k, but of course this would + * too simple to be enough. 4k turned out to be too small an + * alignment very soon, and in fact it is almost impossible to + * keep the table size stable for all (max_cpus, max_memory_slots) + * combinations. So the table size is always 64k for pc-i440fx-2.1 + * and we give an error if the table grows beyond that limit. + * + * We still have the problem of migrating from "-M pc-i440fx-2.0". For + * that, we exploit the fact that QEMU 2.1 generates _smaller_ tables + * than 2.0 and we can always pad the smaller tables with zeros. We can + * then use the exact size of the 2.0 tables. + * + * All this is for PIIX4, since QEMU 2.0 didn't support Q35 migration. */ - acpi_align_size(tables->table_data, 0x1000); + if (guest_info->legacy_acpi_table_size) { + /* Subtracting aml_len gives the size of fixed tables. Then add the + * size of the PIIX4 DSDT/SSDT in QEMU 2.0. + */ + int legacy_aml_len = + guest_info->legacy_acpi_table_size + + ACPI_BUILD_LEGACY_CPU_AML_SIZE * max_cpus; + int legacy_table_size = + ROUND_UP(tables->table_data->len - aml_len + legacy_aml_len, + ACPI_BUILD_ALIGN_SIZE); + if (tables->table_data->len > legacy_table_size) { + /* Should happen only with PCI bridges and -M pc-i440fx-2.0. */ + error_report("Warning: migration to QEMU 2.0 may not work."); + } + g_array_set_size(tables->table_data, legacy_table_size); + } else { + acpi_align_size(tables->table_data, ACPI_BUILD_ALIGN_SIZE); + } - acpi_align_size(tables->linker, 0x1000); + acpi_align_size(tables->linker, ACPI_BUILD_ALIGN_SIZE); /* Cleanup memory that's no longer used. */ g_array_free(table_offsets, true); diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c index 7081c08a69..4524e6b56e 100644 --- a/hw/i386/pc_piix.c +++ b/hw/i386/pc_piix.c @@ -61,6 +61,7 @@ static const int ide_irq[MAX_IDE_BUS] = { 14, 15 }; static bool has_pci_info; static bool has_acpi_build = true; +static int legacy_acpi_table_size; static bool smbios_defaults = true; static bool smbios_legacy_mode; /* Make sure that guest addresses aligned at 1Gbyte boundaries get mapped to @@ -163,6 +164,7 @@ static void pc_init1(MachineState *machine, guest_info = pc_guest_info_init(below_4g_mem_size, above_4g_mem_size); guest_info->has_acpi_build = has_acpi_build; + guest_info->legacy_acpi_table_size = legacy_acpi_table_size; guest_info->has_pci_info = has_pci_info; guest_info->isapc_ram_fw = !pci_enabled; @@ -297,6 +299,23 @@ static void pc_init_pci(MachineState *machine) static void pc_compat_2_0(MachineState *machine) { + /* This value depends on the actual DSDT and SSDT compiled into + * the source QEMU; unfortunately it depends on the binary and + * not on the machine type, so we cannot make pc-i440fx-1.7 work on + * both QEMU 1.7 and QEMU 2.0. + * + * Large variations cause migration to fail for more than one + * consecutive value of the "-smp" maxcpus option. + * + * For small variations of the kind caused by different iasl versions, + * the 4k rounding usually leaves slack. However, there could be still + * one or two values that break. For QEMU 1.7 and QEMU 2.0 the + * slack is only ~10 bytes before one "-smp maxcpus" value breaks! + * + * 6652 is valid for QEMU 2.0, the right value for pc-i440fx-1.7 on + * QEMU 1.7 it is 6414. For RHEL/CentOS 7.0 it is 6418. + */ + legacy_acpi_table_size = 6652; smbios_legacy_mode = true; has_reserved_memory = false; } diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c index f55196150c..c39ee98933 100644 --- a/hw/i386/pc_q35.c +++ b/hw/i386/pc_q35.c @@ -155,6 +155,11 @@ static void pc_q35_init(MachineState *machine) guest_info->has_acpi_build = has_acpi_build; guest_info->has_reserved_memory = has_reserved_memory; + /* Migration was not supported in 2.0 for Q35, so do not bother + * with this hack (see hw/i386/acpi-build.c). + */ + guest_info->legacy_acpi_table_size = 0; + if (smbios_defaults) { MachineClass *mc = MACHINE_GET_CLASS(machine); /* These values are guest ABI, do not change */ diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h index 1c0c382d8c..f4b9b2bb71 100644 --- a/include/hw/i386/pc.h +++ b/include/hw/i386/pc.h @@ -94,6 +94,7 @@ struct PcGuestInfo { uint64_t *node_mem; uint64_t *node_cpu; FWCfgState *fw_cfg; + int legacy_acpi_table_size; bool has_acpi_build; bool has_reserved_memory; };