@@ -865,7 +865,8 @@ void virt_acpi_setup(VirtMachineState *vms)
build_state->linker_mr =
acpi_add_rom_blob(virt_acpi_build_update, build_state,
- tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE, 0);
+ tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
+ ACPI_BUILD_LOADER_MAX_SIZE);
fw_cfg_add_file(vms->fw_cfg, ACPI_BUILD_TPMLOG_FILE, tables.tcpalog->data,
acpi_data_len(tables.tcpalog));
@@ -2524,7 +2524,8 @@ void acpi_setup(void)
build_state->linker_mr =
acpi_add_rom_blob(acpi_build_update, build_state,
- tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE, 0);
+ tables.linker->cmd_blob, ACPI_BUILD_LOADER_FILE,
+ ACPI_BUILD_LOADER_MAX_SIZE);
fw_cfg_add_file(x86ms->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
tables.tcpalog->data, acpi_data_len(tables.tcpalog));
@@ -255,7 +255,7 @@ void acpi_setup_microvm(MicrovmMachineState *mms)
ACPI_BUILD_TABLE_MAX_SIZE);
acpi_add_rom_blob(acpi_build_no_update, NULL,
tables.linker->cmd_blob,
- "etc/table-loader", 0);
+ "etc/table-loader", ACPI_BUILD_LOADER_MAX_SIZE);
acpi_add_rom_blob(acpi_build_no_update, NULL,
tables.rsdp,
ACPI_BUILD_RSDP_FILE, 0);
@@ -6,6 +6,7 @@
/* Reserve RAM space for tables: add another order of magnitude. */
#define ACPI_BUILD_TABLE_MAX_SIZE 0x200000
+#define ACPI_BUILD_LOADER_MAX_SIZE 0x10000
#define ACPI_BUILD_APPNAME6 "BOCHS "
#define ACPI_BUILD_APPNAME8 "BXPC "
The resizeable memory region / RAMBlock that is created for the cmd blob has a maximum size of whole host pages (e.g., 4k), because RAMBlocks work on full host pages. In addition, in i386 ACPI code: acpi_align_size(tables->linker->cmd_blob, ACPI_BUILD_ALIGN_SIZE); makes sure to align to multiples of 4k, padding with 0. For example, if our cmd_blob is created with a size of 2k, the maximum size is 4k - we cannot grow beyond that. Growing might be required due to guest action when rebuilding the tables, but also on incoming migration. This automatic generation of the maximum size used to be sufficient, however, there are cases where we cross host pages now when growing at runtime: we exceed the maximum size of the RAMBlock and can crash QEMU when trying to resize the resizeable memory region / RAMBlock: $ build/qemu-system-x86_64 --enable-kvm \ -machine q35,nvdimm=on \ -smp 1 \ -cpu host \ -m size=2G,slots=8,maxmem=4G \ -object memory-backend-file,id=mem0,mem-path=/tmp/nvdimm,size=256M \ -device nvdimm,label-size=131072,memdev=mem0,id=nvdimm0,slot=1 \ -nodefaults \ -device vmgenid \ -device intel-iommu Results in: Unexpected error in qemu_ram_resize() at ../softmmu/physmem.c:1850: qemu-system-x86_64: Size too large: /rom@etc/table-loader: 0x2000 > 0x1000: Invalid argument In this configuration, we consume exactly 4k (32 entries, 128 bytes each) when creating the VM. However, once the guest boots up and maps the MCFG, we also create the MCFG table and end up consuming 2 additional entries (pointer + checksum) -- which is where we try resizing the memory region / RAMBlock, however, the maximum size does not allow for it. Currently, we get the following maximum sizes for our different mutable tables based on behavior of resizeable RAMBlock: hw table max_size ------- --------------------------------------------------------- virt "etc/acpi/tables" ACPI_BUILD_TABLE_MAX_SIZE (0x200000) virt "etc/table-loader" HOST_PAGE_ALIGN(initial_size) virt "etc/acpi/rsdp" HOST_PAGE_ALIGN(initial_size) i386 "etc/acpi/tables" ACPI_BUILD_TABLE_MAX_SIZE (0x200000) i386 "etc/table-loader" HOST_PAGE_ALIGN(initial_size) i386 "etc/acpi/rsdp" HOST_PAGE_ALIGN(initial_size) microvm "etc/acpi/tables" ACPI_BUILD_TABLE_MAX_SIZE (0x200000) microvm "etc/table-loader" HOST_PAGE_ALIGN(initial_size) microvm "etc/acpi/rsdp" HOST_PAGE_ALIGN(initial_size) Let's set the maximum table size for "etc/table-loader" to 64k, so we can properly grow at runtime, which should be good enough for the future. Migration is not concerned with the maximum size of a RAMBlock, only with the used size - so existing setups are not affected. Of course, we cannot migrate a VM that would have crash when started on older QEMU from new QEMU to older QEMU without failing early on the destination when synchronizing the RAM state: qemu-system-x86_64: Size too large: /rom@etc/table-loader: 0x2000 > 0x1000: Invalid argument qemu-system-x86_64: error while loading state for instance 0x0 of device 'ram' qemu-system-x86_64: load of migration failed: Invalid argument We'll refactor the code next, to make sure we get rid of this implicit behavior for "etc/acpi/rsdp" as well and to make the code easier to grasp. Reviewed-by: Igor Mammedov <imammedo@redhat.com> Cc: Alistair Francis <alistair.francis@xilinx.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Peter Maydell <peter.maydell@linaro.org> Cc: Shannon Zhao <shannon.zhaosl@gmail.com> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Laszlo Ersek <lersek@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> --- hw/arm/virt-acpi-build.c | 3 ++- hw/i386/acpi-build.c | 3 ++- hw/i386/acpi-microvm.c | 2 +- include/hw/acpi/aml-build.h | 1 + 4 files changed, 6 insertions(+), 3 deletions(-)