On Fri, May 08, 2015 at 03:21:35PM +0530, Bharata B Rao wrote: > Currently CPUState.cpu_index is monotonically increasing and a newly > created CPU always gets the next higher index. The next available > index is calculated by counting the existing number of CPUs. This is > fine as long as we only add CPUs, but there are architectures which > are starting to support CPU removal too. For an architecture like PowerPC > which derives its CPU identifier (device tree ID) from cpu_index, the > existing logic of generating cpu_index values causes problems. > > With the currently proposed method of handling vCPU removal by parking > the vCPU fd in QEMU > (Ref: http://lists.gnu.org/archive/html/qemu-devel/2015-02/msg02604.html), > generating cpu_index this way will not work for PowerPC. > > This patch changes the way cpu_index is handed out by maintaining > a bit map of the CPUs that tracks both addition and removal of CPUs. > > The CPU bitmap allocation logic is part of cpu_exec_init() which is > called by instance_init routines of various CPU targets. This patch > also adds corresponding instance_finalize routine if needed for these > CPU targets so that CPU can be marked free when it is removed. > > Signed-off-by: Bharata B Rao <[email protected]> > --- > exec.c | 37 ++++++++++++++++++++++++++++++++++--- > include/qom/cpu.h | 8 ++++++++ > target-alpha/cpu.c | 6 ++++++ > target-arm/cpu.c | 1 + > target-cris/cpu.c | 6 ++++++ > target-i386/cpu.c | 6 ++++++ > target-lm32/cpu.c | 6 ++++++ > target-m68k/cpu.c | 6 ++++++ > target-microblaze/cpu.c | 6 ++++++ > target-mips/cpu.c | 6 ++++++ > target-moxie/cpu.c | 6 ++++++ > target-openrisc/cpu.c | 6 ++++++ > target-ppc/translate_init.c | 6 ++++++ > target-s390x/cpu.c | 1 + > target-sh4/cpu.c | 6 ++++++ > target-sparc/cpu.c | 1 + > target-tricore/cpu.c | 5 +++++ > target-unicore32/cpu.c | 6 ++++++ > target-xtensa/cpu.c | 6 ++++++ > 19 files changed, 128 insertions(+), 3 deletions(-)
Why not simply call cpu_exec_exit() on generic CPU::instance_finalize, to avoid forcing every architecture to call it manually? Calling cpu_exec_exit() twice would be harmless, anyway. (It would just need an additional check to make sure the bit will be cleared only if cpu_exec_init() was really called and cpu_index was properly set.) -- Eduardo
