[Qemu-devel] Re: [PATCH 15/21] qemu-kvm: Clean up mpstate synchronization

[Gleb Natapov <gleb@redhat.com>]

On Tue, Feb 02, 2010 at 09:19:01AM +0100, Jan Kiszka wrote:
> Push mpstate reading/writing into kvm_arch_load/save_regs and, on x86,
> properly synchronize with halted in the accessor functions.
> 
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  hw/apic.c             |    7 ----
>  qemu-kvm-ia64.c       |    4 ++-
>  qemu-kvm-x86.c        |   88 +++++++++++++++++++++++++++---------------------
>  qemu-kvm.c            |   30 -----------------
>  qemu-kvm.h            |   15 --------
>  target-i386/machine.c |    6 ---
>  target-ia64/machine.c |    3 ++
>  7 files changed, 55 insertions(+), 98 deletions(-)
> 
> diff --git a/hw/apic.c b/hw/apic.c
> index 3e03e10..092c61e 100644
> --- a/hw/apic.c
> +++ b/hw/apic.c
> @@ -507,13 +507,6 @@ void apic_init_reset(CPUState *env)
>      s->wait_for_sipi = 1;
>  
>      env->halted = !(s->apicbase & MSR_IA32_APICBASE_BSP);
> -#ifdef KVM_CAP_MP_STATE
> -    if (kvm_enabled() && kvm_irqchip_in_kernel()) {
> -        env->mp_state
> -            = env->halted ? KVM_MP_STATE_UNINITIALIZED : KVM_MP_STATE_RUNNABLE;
> -        kvm_load_mpstate(env);
> -    }
> -#endif
>  }
>  
>  static void apic_startup(APICState *s, int vector_num)
> diff --git a/qemu-kvm-ia64.c b/qemu-kvm-ia64.c
> index fc8110e..39bcbeb 100644
> --- a/qemu-kvm-ia64.c
> +++ b/qemu-kvm-ia64.c
> @@ -124,7 +124,9 @@ void kvm_arch_cpu_reset(CPUState *env)
>  {
>      if (kvm_irqchip_in_kernel(kvm_context)) {
>  #ifdef KVM_CAP_MP_STATE
> -	kvm_reset_mpstate(env->kvm_cpu_state.vcpu_ctx);
> +        struct kvm_mp_state mp_state = {.mp_state = KVM_MP_STATE_UNINITIALIZED
> +        };
> +        kvm_set_mpstate(env, &mp_state);
>  #endif
>      } else {
>  	env->interrupt_request &= ~CPU_INTERRUPT_HARD;
> diff --git a/qemu-kvm-x86.c b/qemu-kvm-x86.c
> index 63cd095..6b5895f 100644
> --- a/qemu-kvm-x86.c
> +++ b/qemu-kvm-x86.c
> @@ -754,6 +754,48 @@ static int get_msr_entry(struct kvm_msr_entry *entry, CPUState *env)
>          return 0;
>  }
>  
> +static void kvm_arch_save_mpstate(CPUState *env)
> +{
> +#ifdef KVM_CAP_MP_STATE
> +    int r;
> +    struct kvm_mp_state mp_state;
> +
> +    r = kvm_get_mpstate(env, &mp_state);
> +    if (r < 0) {
> +        env->mp_state = -1;
> +    } else {
> +        env->mp_state = mp_state.mp_state;
> +        if (kvm_irqchip_in_kernel()) {
> +            env->halted = (env->mp_state == KVM_MP_STATE_HALTED);
> +        }
> +    }
> +#else
> +    env->mp_state = -1;
> +#endif
> +}
> +
> +static void kvm_arch_load_mpstate(CPUState *env)
> +{
> +#ifdef KVM_CAP_MP_STATE
> +    struct kvm_mp_state mp_state;
> +
> +    /*
> +     * -1 indicates that the host did not support GET_MP_STATE ioctl,
> +     *  so don't touch it.
> +     */
> +    if (env->mp_state != -1) {
> +        if (kvm_irqchip_in_kernel()) {
> +            env->mp_state = env->halted ? KVM_MP_STATE_UNINITIALIZED :
> +                                          KVM_MP_STATE_RUNNABLE;
When irqchip is in kernel env->halted doesn't contain any relevant
information, so this is incorrect. Actually env->halted is updated only
to show correct cpu state during "info cpus".

> +            /* Avoid deadlock: no user space IRQ will ever clear it. */
And this comment explains why looking at env->halt when irqchip is in
kernel is wrong :)

> +            env->halted = 0;
> +        }
> +        mp_state.mp_state = env->mp_state;
> +        kvm_set_mpstate(env, &mp_state);
> +    }
> +#endif
> +}
> +
>  static void set_v8086_seg(struct kvm_segment *lhs, const SegmentCache *rhs)
>  {
>      lhs->selector = rhs->selector;
> @@ -926,6 +968,10 @@ void kvm_arch_load_regs(CPUState *env, int level)
>      rc = kvm_set_msrs(env, msrs, n);
>      if (rc == -1)
>          perror("kvm_set_msrs FAILED");
> +
> +    if (level >= KVM_PUT_RESET_STATE) {
> +        kvm_arch_load_mpstate(env);
> +    }
>  }
>  
>  void kvm_load_tsc(CPUState *env)
> @@ -940,36 +986,6 @@ void kvm_load_tsc(CPUState *env)
>          perror("kvm_set_tsc FAILED.\n");
>  }
>  
> -void kvm_arch_save_mpstate(CPUState *env)
> -{
> -#ifdef KVM_CAP_MP_STATE
> -    int r;
> -    struct kvm_mp_state mp_state;
> -
> -    r = kvm_get_mpstate(env, &mp_state);
> -    if (r < 0)
> -        env->mp_state = -1;
> -    else
> -        env->mp_state = mp_state.mp_state;
> -#else
> -    env->mp_state = -1;
> -#endif
> -}
> -
> -void kvm_arch_load_mpstate(CPUState *env)
> -{
> -#ifdef KVM_CAP_MP_STATE
> -    struct kvm_mp_state mp_state = { .mp_state = env->mp_state };
> -
> -    /*
> -     * -1 indicates that the host did not support GET_MP_STATE ioctl,
> -     *  so don't touch it.
> -     */
> -    if (env->mp_state != -1)
> -        kvm_set_mpstate(env, &mp_state);
> -#endif
> -}
> -
>  void kvm_arch_save_regs(CPUState *env)
>  {
>      struct kvm_regs regs;
> @@ -1366,15 +1382,9 @@ void kvm_arch_cpu_reset(CPUState *env)
>  {
>      kvm_arch_reset_vcpu(env);
>      kvm_put_vcpu_events(env);
> -    if (!cpu_is_bsp(env)) {
> -	if (kvm_irqchip_in_kernel()) {
> -#ifdef KVM_CAP_MP_STATE
> -	    kvm_reset_mpstate(env);
> -#endif
> -	} else {
> -	    env->interrupt_request &= ~CPU_INTERRUPT_HARD;
> -	    env->halted = 1;
> -	}
> +    if (!cpu_is_bsp(env) && !kvm_irqchip_in_kernel()) {
> +        env->interrupt_request &= ~CPU_INTERRUPT_HARD;
> +        env->halted = 1;
>      }
>  }
>  
> diff --git a/qemu-kvm.c b/qemu-kvm.c
> index 53030f1..efa6a29 100644
> --- a/qemu-kvm.c
> +++ b/qemu-kvm.c
> @@ -1579,36 +1579,6 @@ void kvm_update_interrupt_request(CPUState *env)
>      }
>  }
>  
> -static void kvm_do_load_mpstate(void *_env)
> -{
> -    CPUState *env = _env;
> -
> -    kvm_arch_load_mpstate(env);
> -}
> -
> -void kvm_load_mpstate(CPUState *env)
> -{
> -    if (kvm_enabled() && qemu_system_ready && kvm_vcpu_inited(env))
> -        on_vcpu(env, kvm_do_load_mpstate, env);
> -}
> -
> -static void kvm_do_save_mpstate(void *_env)
> -{
> -    CPUState *env = _env;
> -
> -    kvm_arch_save_mpstate(env);
> -#ifdef KVM_CAP_MP_STATE
> -    if (kvm_irqchip_in_kernel())
> -        env->halted = (env->mp_state == KVM_MP_STATE_HALTED);
> -#endif
> -}
> -
> -void kvm_save_mpstate(CPUState *env)
> -{
> -    if (kvm_enabled())
> -        on_vcpu(env, kvm_do_save_mpstate, env);
> -}
> -
>  int kvm_cpu_exec(CPUState *env)
>  {
>      int r;
> diff --git a/qemu-kvm.h b/qemu-kvm.h
> index 6d785a0..aa7bcce 100644
> --- a/qemu-kvm.h
> +++ b/qemu-kvm.h
> @@ -299,16 +299,6 @@ int kvm_get_mpstate(CPUState *env, struct kvm_mp_state *mp_state);
>   *
>   */
>  int kvm_set_mpstate(CPUState *env, struct kvm_mp_state *mp_state);
> -/*!
> - *  * \brief Reset VCPU MP state
> - *
> - */
> -static inline int kvm_reset_mpstate(CPUState *env)
> -{
> -    struct kvm_mp_state mp_state = {.mp_state = KVM_MP_STATE_UNINITIALIZED
> -    };
> -    return kvm_set_mpstate(env, &mp_state);
> -}
>  #endif
>  
>  /*!
> @@ -874,8 +864,6 @@ static inline void kvm_inject_x86_mce(CPUState *cenv, int bank,
>  int kvm_main_loop(void);
>  int kvm_init_ap(void);
>  int kvm_vcpu_inited(CPUState *env);
> -void kvm_load_mpstate(CPUState *env);
> -void kvm_save_mpstate(CPUState *env);
>  void kvm_apic_init(CPUState *env);
>  /* called from vcpu initialization */
>  void qemu_kvm_load_lapic(CPUState *env);
> @@ -909,8 +897,6 @@ int kvm_arch_qemu_create_context(void);
>  
>  void kvm_arch_save_regs(CPUState *env);
>  void kvm_arch_load_regs(CPUState *env, int level);
> -void kvm_arch_load_mpstate(CPUState *env);
> -void kvm_arch_save_mpstate(CPUState *env);
>  int kvm_arch_has_work(CPUState *env);
>  void kvm_arch_process_irqchip_events(CPUState *env);
>  int kvm_arch_try_push_interrupts(void *opaque);
> @@ -979,7 +965,6 @@ void kvm_load_tsc(CPUState *env);
>  #ifdef TARGET_I386
>  #define qemu_kvm_has_pit_state2() (0)
>  #endif
> -#define kvm_save_mpstate(env)   do {} while(0)
>  #define qemu_kvm_cpu_stop(env) do {} while(0)
>  static inline void kvm_load_tsc(CPUState *env)
>  {
> diff --git a/target-i386/machine.c b/target-i386/machine.c
> index bebde82..61e6a87 100644
> --- a/target-i386/machine.c
> +++ b/target-i386/machine.c
> @@ -323,7 +323,6 @@ static void cpu_pre_save(void *opaque)
>      int i;
>  
>      if (kvm_enabled()) {
> -        kvm_save_mpstate(env);
>          kvm_get_vcpu_events(env);
>      }
>  
> @@ -362,12 +361,7 @@ static int cpu_post_load(void *opaque, int version_id)
>      tlb_flush(env, 1);
>  
>      if (kvm_enabled()) {
> -        /* when in-kernel irqchip is used, env->halted causes deadlock
> -           because no userspace IRQs will ever clear this flag */
> -        env->halted = 0;
> -
>          kvm_load_tsc(env);
> -        kvm_load_mpstate(env);
>          kvm_put_vcpu_events(env);
>      }
>  
> diff --git a/target-ia64/machine.c b/target-ia64/machine.c
> index fdbeeef..8cf5bdd 100644
> --- a/target-ia64/machine.c
> +++ b/target-ia64/machine.c
> @@ -4,6 +4,9 @@
>  #include "exec-all.h"
>  #include "qemu-kvm.h"
>  
> +void kvm_arch_save_mpstate(CPUState *env);
> +void kvm_arch_load_mpstate(CPUState *env);
> +
>  void cpu_save(QEMUFile *f, void *opaque)
>  {
>      CPUState *env = opaque;
> -- 
> 1.6.0.2
> 
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--
			Gleb.