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

[Claudio Fontana <cfontana@suse.de>]

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.

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,