CPU address spaces touching load and store helpers as well as the movement of (almost) all fields from CPU_COMMON to CPUState have led to a noticeable increase of CPU() usage in "hot" paths for both TCG and KVM.
While CPU()'s OBJECT_CHECK() might help detect development errors, i.e. in form of crashes due to QOM vs. non-QOM mismatches rather than QOM type mismatches, it is not really needed at runtime since mostly used in CPU-specific paths, coming from a target-specific CPU subtype. If that pointer is damaged, other errors are highly likely to occur elsewhere anyway. Keep the CPU() macro for a consistent developer experience and for flexibility to exchange its implementation, but turn it into a pure, unchecked C cast for now. Compare commit 6e42be7cd10260fd3a006d94f6c870692bf7a2c0. Reported-by: Laurent Desnogues <laurent.desnog...@gmail.com> Suggested-by: Paolo Bonzini <pbonz...@redhat.com> Signed-off-by: Andreas Färber <afaer...@suse.de> --- include/qom/cpu.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/include/qom/cpu.h b/include/qom/cpu.h index f99885a..df977c8 100644 --- a/include/qom/cpu.h +++ b/include/qom/cpu.h @@ -53,7 +53,12 @@ typedef uint64_t vaddr; #define TYPE_CPU "cpu" -#define CPU(obj) OBJECT_CHECK(CPUState, (obj), TYPE_CPU) +/* Since this macro is used a lot in hot code paths and in conjunction with + * FooCPU *foo_env_get_cpu(), we deviate from usual QOM practice by using + * an unchecked cast. + */ +#define CPU(obj) ((CPUState *)(obj)) + #define CPU_CLASS(class) OBJECT_CLASS_CHECK(CPUClass, (class), TYPE_CPU) #define CPU_GET_CLASS(obj) OBJECT_GET_CLASS(CPUClass, (obj), TYPE_CPU) -- 1.8.4.5
