On Tue, Mar 17, 2015 at 07:56:41AM +0100, Alexander Graf wrote: > > > On 13.03.15 12:56, Bharata B Rao wrote: > > From: Bharata B Rao <bharata....@gmail.com> > > > > 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. > > > > I am not sure if this is the right and an acceptable approach. The > > alternative is to do something similar for PowerPC alone and not > > depend on cpu_index. > > > > I have tested this with out-of-the-tree patches for CPU hot plug and > > removal on x86 and sPAPR PowerPC. > > > > Signed-off-by: Bharata B Rao <bhar...@linux.vnet.ibm.com> > > --- > > exec.c | 39 +++++++++++++++++++++++++++++---------- > > include/exec/exec-all.h | 1 + > > 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, 116 insertions(+), 10 deletions(-) > > > > diff --git a/exec.c b/exec.c > > index e97071a..7760f2d 100644 > > --- a/exec.c > > +++ b/exec.c > > @@ -530,21 +530,40 @@ void tcg_cpu_address_space_init(CPUState *cpu, > > AddressSpace *as) > > } > > #endif > > > > +static DECLARE_BITMAP(cpu_index_map, MAX_CPUMASK_BITS); > > + > > +#ifdef CONFIG_USER_ONLY > > +int max_cpus = 1; /* TODO: Check if this is correct ? */ > > +#endif > > + > > +static int cpu_get_free_index(void) > > +{ > > + int cpu = find_first_zero_bit(cpu_index_map, max_cpus); > > + > > + if (cpu == max_cpus) { > > + fprintf(stderr, "WARNING: qemu: Trying to use more " > > + "CPUs than allowed max of %d\n", max_cpus); > > + return max_cpus; > > + } else { > > + bitmap_set(cpu_index_map, cpu, 1); > > + return cpu; > > + } > > +} > > + > > +void cpu_exec_exit(CPUState *cpu) > > +{ > > + bitmap_clear(cpu_index_map, cpu->cpu_index, 1); > > +} > > + > > void cpu_exec_init(CPUArchState *env) > > { > > CPUState *cpu = ENV_GET_CPU(env); > > CPUClass *cc = CPU_GET_CLASS(cpu); > > - CPUState *some_cpu; > > - int cpu_index; > > > > #if defined(CONFIG_USER_ONLY) > > cpu_list_lock(); > > #endif > > - cpu_index = 0; > > - CPU_FOREACH(some_cpu) { > > - cpu_index++; > > - } > > - cpu->cpu_index = cpu_index; > > + cpu->cpu_index = cpu_get_free_index(); > > cpu->numa_node = 0; > > QTAILQ_INIT(&cpu->breakpoints); > > QTAILQ_INIT(&cpu->watchpoints); > > @@ -558,16 +577,16 @@ void cpu_exec_init(CPUArchState *env) > > cpu_list_unlock(); > > #endif > > if (qdev_get_vmsd(DEVICE(cpu)) == NULL) { > > - vmstate_register(NULL, cpu_index, &vmstate_cpu_common, cpu); > > + vmstate_register(NULL, cpu->cpu_index, &vmstate_cpu_common, cpu); > > } > > #if defined(CPU_SAVE_VERSION) && !defined(CONFIG_USER_ONLY) > > - register_savevm(NULL, "cpu", cpu_index, CPU_SAVE_VERSION, > > + register_savevm(NULL, "cpu", cpu->cpu_index, CPU_SAVE_VERSION, > > cpu_save, cpu_load, env); > > assert(cc->vmsd == NULL); > > assert(qdev_get_vmsd(DEVICE(cpu)) == NULL); > > #endif > > if (cc->vmsd != NULL) { > > - vmstate_register(NULL, cpu_index, cc->vmsd, cpu); > > + vmstate_register(NULL, cpu->cpu_index, cc->vmsd, cpu); > > } > > } > > > > diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h > > index 8eb0db3..95fbba0 100644 > > --- a/include/exec/exec-all.h > > +++ b/include/exec/exec-all.h > > @@ -89,6 +89,7 @@ TranslationBlock *tb_gen_code(CPUState *cpu, > > target_ulong pc, target_ulong cs_base, int > > flags, > > int cflags); > > void cpu_exec_init(CPUArchState *env); > > +void cpu_exec_exit(CPUState *cpu); > > void QEMU_NORETURN cpu_loop_exit(CPUState *cpu); > > int page_unprotect(target_ulong address, uintptr_t pc, void *puc); > > void tb_invalidate_phys_page_range(tb_page_addr_t start, tb_page_addr_t > > end, > > diff --git a/target-alpha/cpu.c b/target-alpha/cpu.c > > index a98b7d8..7c57165 100644 > > --- a/target-alpha/cpu.c > > +++ b/target-alpha/cpu.c > > @@ -250,6 +250,11 @@ static const TypeInfo ev68_cpu_type_info = { > > .parent = TYPE("ev67"), > > }; > > > > +static void alpha_cpu_finalize(Object *obj) > > +{ > > + cpu_exec_exit(CPU(obj)); > > +} > > + > > static void alpha_cpu_initfn(Object *obj) > > { > > CPUState *cs = CPU(obj); > > @@ -305,6 +310,7 @@ static const TypeInfo alpha_cpu_type_info = { > > .parent = TYPE_CPU, > > .instance_size = sizeof(AlphaCPU), > > .instance_init = alpha_cpu_initfn, > > + .instance_finalize = alpha_cpu_finalize, > > Would it be possible to put this into TYPE_CPU->instance_finalize instead?
Yes possible and that would be much cleaner since I wouldn't have to touch all archs. But it will be asymmetric in some sense as cpu_exec_init() is called from all individual cpus' instance_init but cpu_exec_exit() will be called from parent's (TYPE_CPU) instance_finalize. If that is fine, I shall post v2 with this change. Regards, Bharata.
