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 b170fce3dd ("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 <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Cc: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20210517105140.1062037-13-f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
overall, all devices' realize functions take an Error **errp, but return void.
hw/core/qdev.c code, which realizes devices, therefore does:
local_err = NULL;
dc->realize(dev, &local_err);
if (local_err != NULL) {
goto fail;
}
However, we can improve at least accel_cpu to return a meaningful bool value.
Signed-off-by: Claudio Fontana <cfontana@suse.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210322132800.7470-9-cfontana@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The TCG-specific CPU methods will be moved to a separate struct,
to make it easier to move accel-specific code outside generic CPU
code in the future. Start by moving tcg_initialize().
The new CPUClass.tcg_opts field may eventually become a pointer,
but keep it an embedded struct for now, to make code conversion
easier.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
[claudio: move TCGCpuOperations inside include/hw/core/cpu.h]
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210204163931.7358-2-cfontana@suse.de>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Enable removing tcg/$tcg_arch from the include path when TCG is disabled.
Move translate-all.h to include/exec, since stubs exist for the functions
defined therein.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Over the years, most parts of exec.c that were not specific to softmmu
have been moved to accel/tcg; what's left is mostly the low-level part
of the memory API, which includes RAMBlock and AddressSpaceDispatch.
However exec.c also hosts 4-500 lines of code for the target specific
parts of the CPU QOM object, plus a few functions for user-mode
emulation that do not have a better place (they are not TCG-specific so
accel/tcg/user-exec.c is not a good place either).
Move these parts to a new file, so that exec.c can be moved to
softmmu/physmem.c.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
