From 744c72a837a0428f2d5373793e42aba963bf47c6 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= Date: Mon, 17 May 2021 12:51:29 +0200 Subject: cpu: Rename CPUClass vmsd -> legacy_vmsd MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Quoting Peter Maydell [*]: There are two ways to handle migration for a CPU object: (1) like any other device, so it has a dc->vmsd that covers migration for the whole object. As usual for objects that are a subclass of a parent that has state, the first entry in the VMStateDescription field list is VMSTATE_CPU(), which migrates the cpu_common fields, followed by whatever the CPU's own migration fields are. (2) a backwards-compatible mechanism for CPUs that were originally migrated using manual "write fields to the migration stream structures". The on-the-wire migration format for those is based on the 'env' pointer (which isn't a QOM object), and the cpu_common part of the migration data is elsewhere. cpu_exec_realizefn() handles both possibilities: * for type 1, dc->vmsd is set and cc->vmsd is not, so cpu_exec_realizefn() does nothing, and the standard "register dc->vmsd for a device" code does everything needed * for type 2, dc->vmsd is NULL and so we register the vmstate_cpu_common directly to handle the cpu-common fields, and the cc->vmsd to handle the per-CPU stuff You can't change a CPU from one type to the other without breaking migration compatibility, which is why some guest architectures are stuck on the cc->vmsd form. New targets should use dc->vmsd. To avoid new targets to start using type (2), rename cc->vmsd as cc->legacy_vmsd. The correct field to implement is dc->vmsd (the DeviceClass one). See also commit b170fce3dd0 ("cpu: Register VMStateDescription through CPUState") for historic background. [*] https://www.mail-archive.com/qemu-devel@nongnu.org/msg800849.html Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Richard Henderson Cc: Peter Maydell Message-Id: <20210517105140.1062037-13-f4bug@amsat.org> Signed-off-by: Richard Henderson --- include/hw/core/cpu.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'include/hw/core') diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h index d96ff4d..1dfb788 100644 --- a/include/hw/core/cpu.h +++ b/include/hw/core/cpu.h @@ -122,7 +122,8 @@ struct AccelCPUClass; * 32-bit VM coredump. * @write_elf32_qemunote: Callback for writing a CPU- and QEMU-specific ELF * note to a 32-bit VM coredump. - * @vmsd: State description for migration. + * @legacy_vmsd: Legacy state description for migration. + * Do not use in new targets, use #DeviceClass::vmsd instead. * @gdb_num_core_regs: Number of core registers accessible to GDB. * @gdb_core_xml_file: File name for core registers GDB XML description. * @gdb_stop_before_watchpoint: Indicates whether GDB expects the CPU to stop @@ -177,7 +178,7 @@ struct CPUClass { int (*write_elf32_qemunote)(WriteCoreDumpFunction f, CPUState *cpu, void *opaque); - const VMStateDescription *vmsd; + const VMStateDescription *legacy_vmsd; const char *gdb_core_xml_file; gchar * (*gdb_arch_name)(CPUState *cpu); const char * (*gdb_get_dynamic_xml)(CPUState *cpu, const char *xmlname); -- cgit v1.1