Re: [PATCH 03/10] accel/tcg: move i386 halt handling to sysemu_ops

["Alex Bennée" <alex.bennee@linaro.org>]

Claudio Fontana <cfontana@suse.de> writes:

> Hi Alex, all,
>
> again, this moves TCG-only code to common code, no?
>
> Even if this happens to work, the idea is to avoid adding unneeded accel TCG code to a KVM-only binary.
>
> We need to keep in mind all dimensions when we do refactorings:
>
> user-mode vs sysemu,
> the architecture,
> the accel, in particular tcg, non-tcg (which could be not compiled in,
> built-in, or loaded as separate module).
>
> In many cases, testing with --disable-tcg --enable-kvm helps to avoid breakages,
> but it is possible also to move in unneeded code in a way that does
> not generate compile or link-time errors, so we need to be a bit alert
> to that.

You are right of course, it should be kept tcg only. I guess using
tcgops instead of sysemu_ops.

>
> Ciao,
>
> C 
>
>
> On 3/20/23 11:10, Alex Bennée wrote:
>> We don't want to be polluting the core run loop code with target
>> specific handling, punt it to sysemu_ops where it belongs.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>> ---
>>  include/hw/core/sysemu-cpu-ops.h |  5 +++++
>>  target/i386/cpu-internal.h       |  1 +
>>  accel/tcg/cpu-exec.c             | 14 +++-----------
>>  target/i386/cpu-sysemu.c         | 12 ++++++++++++
>>  target/i386/cpu.c                |  1 +
>>  5 files changed, 22 insertions(+), 11 deletions(-)
>> 
>> diff --git a/include/hw/core/sysemu-cpu-ops.h b/include/hw/core/sysemu-cpu-ops.h
>> index ee169b872c..c9d30172c4 100644
>> --- a/include/hw/core/sysemu-cpu-ops.h
>> +++ b/include/hw/core/sysemu-cpu-ops.h
>> @@ -48,6 +48,11 @@ typedef struct SysemuCPUOps {
>>       * GUEST_PANICKED events.
>>       */
>>      GuestPanicInformation* (*get_crash_info)(CPUState *cpu);
>> +    /**
>> +     * @handle_cpu_halt: Callback for special handling during cpu_handle_halt()
>> +     * @cs: The CPUState
>> +     */
>> +    void (*handle_cpu_halt)(CPUState *cpu);
>>      /**
>>       * @write_elf32_note: Callback for writing a CPU-specific ELF note to a
>>       * 32-bit VM coredump.
>> diff --git a/target/i386/cpu-internal.h b/target/i386/cpu-internal.h
>> index 9baac5c0b4..75b302fb33 100644
>> --- a/target/i386/cpu-internal.h
>> +++ b/target/i386/cpu-internal.h
>> @@ -65,6 +65,7 @@ void x86_cpu_get_crash_info_qom(Object *obj, Visitor *v,
>>  void x86_cpu_apic_create(X86CPU *cpu, Error **errp);
>>  void x86_cpu_apic_realize(X86CPU *cpu, Error **errp);
>>  void x86_cpu_machine_reset_cb(void *opaque);
>> +void x86_cpu_handle_halt(CPUState *cs);
>>  #endif /* !CONFIG_USER_ONLY */
>>  
>>  #endif /* I386_CPU_INTERNAL_H */
>> diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
>> index c815f2dbfd..5e5906e199 100644
>> --- a/accel/tcg/cpu-exec.c
>> +++ b/accel/tcg/cpu-exec.c
>> @@ -22,6 +22,7 @@
>>  #include "qapi/error.h"
>>  #include "qapi/type-helpers.h"
>>  #include "hw/core/tcg-cpu-ops.h"
>> +#include "hw/core/sysemu-cpu-ops.h"
>>  #include "trace.h"
>>  #include "disas/disas.h"
>>  #include "exec/exec-all.h"
>> @@ -30,9 +31,6 @@
>>  #include "qemu/rcu.h"
>>  #include "exec/log.h"
>>  #include "qemu/main-loop.h"
>> -#if defined(TARGET_I386) && !defined(CONFIG_USER_ONLY)
>> -#include "hw/i386/apic.h"
>> -#endif
>>  #include "sysemu/cpus.h"
>>  #include "exec/cpu-all.h"
>>  #include "sysemu/cpu-timers.h"
>> @@ -650,15 +648,9 @@ static inline bool cpu_handle_halt(CPUState *cpu)
>>  {
>>  #ifndef CONFIG_USER_ONLY
>>      if (cpu->halted) {
>> -#if defined(TARGET_I386)
>> -        if (cpu->interrupt_request & CPU_INTERRUPT_POLL) {
>> -            X86CPU *x86_cpu = X86_CPU(cpu);
>> -            qemu_mutex_lock_iothread();
>> -            apic_poll_irq(x86_cpu->apic_state);
>> -            cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
>> -            qemu_mutex_unlock_iothread();
>> +        if (cpu->cc->sysemu_ops->handle_cpu_halt) {
>> +            cpu->cc->sysemu_ops->handle_cpu_halt(cpu);
>>          }
>> -#endif /* TARGET_I386 */
>>          if (!cpu_has_work(cpu)) {
>>              return true;
>>          }
>> diff --git a/target/i386/cpu-sysemu.c b/target/i386/cpu-sysemu.c
>> index 28115edf44..e545bf7590 100644
>> --- a/target/i386/cpu-sysemu.c
>> +++ b/target/i386/cpu-sysemu.c
>> @@ -18,6 +18,7 @@
>>   */
>>  
>>  #include "qemu/osdep.h"
>> +#include "qemu/main-loop.h"
>>  #include "cpu.h"
>>  #include "sysemu/xen.h"
>>  #include "sysemu/whpx.h"
>> @@ -310,6 +311,17 @@ void x86_cpu_apic_realize(X86CPU *cpu, Error **errp)
>>       }
>>  }
>>  
>> +void x86_cpu_handle_halt(CPUState *cpu)
>> +{
>> +    if (cpu->interrupt_request & CPU_INTERRUPT_POLL) {
>> +        X86CPU *x86_cpu = X86_CPU(cpu);
>> +        qemu_mutex_lock_iothread();
>> +        apic_poll_irq(x86_cpu->apic_state);
>> +        cpu_reset_interrupt(cpu, CPU_INTERRUPT_POLL);
>> +        qemu_mutex_unlock_iothread();
>> +    }
>> +}
>> +
>>  GuestPanicInformation *x86_cpu_get_crash_info(CPUState *cs)
>>  {
>>      X86CPU *cpu = X86_CPU(cs);
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 6576287e5b..67027d28b0 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -7241,6 +7241,7 @@ static const struct SysemuCPUOps i386_sysemu_ops = {
>>      .get_phys_page_attrs_debug = x86_cpu_get_phys_page_attrs_debug,
>>      .asidx_from_attrs = x86_asidx_from_attrs,
>>      .get_crash_info = x86_cpu_get_crash_info,
>> +    .handle_cpu_halt = x86_cpu_handle_halt,
>>      .write_elf32_note = x86_cpu_write_elf32_note,
>>      .write_elf64_note = x86_cpu_write_elf64_note,
>>      .write_elf32_qemunote = x86_cpu_write_elf32_qemunote,


-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro