Re: [Xen-devel] [PATCH 4/7] ioreq: allow registering internal ioreq server handler

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Roger Pau Monne <roger.pau@xxxxxxxxxx>
> Sent: 21 August 2019 15:59
> To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Roger Pau Monne <roger.pau@xxxxxxxxxx>; Paul Durrant 
> <Paul.Durrant@xxxxxxxxxx>; Jan Beulich
> <jbeulich@xxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Wei Liu 
> <wl@xxxxxxx>
> Subject: [PATCH 4/7] ioreq: allow registering internal ioreq server handler
> 
> Provide a routine to register the handler for an internal ioreq
> server. Note the handler can only be set once.

I'd prefer hvm_set_ioreq_handler() and some sort of guard to prevent enabling 
of an internal server with no handler (probably in the previous patch) would be 
prudent, I think. Also, why the set-once semantic?

  Paul

> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
>  xen/arch/x86/hvm/ioreq.c        | 32 ++++++++++++++++++++++++++++++++
>  xen/include/asm-x86/hvm/ioreq.h |  3 +++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
> index 3fb6fe9585..d8fea191aa 100644
> --- a/xen/arch/x86/hvm/ioreq.c
> +++ b/xen/arch/x86/hvm/ioreq.c
> @@ -486,6 +486,38 @@ static int hvm_add_ioreq_gfn(struct hvm_ioreq_server *s, 
> bool buf)
>      return rc;
>  }
> 
> +int hvm_add_ioreq_handler(struct domain *d, ioservid_t id,
> +                          int (*handler)(struct vcpu *v, ioreq_t *))
> +{
> +    struct hvm_ioreq_server *s;
> +    int rc = 0;
> +
> +    spin_lock_recursive(&d->arch.hvm.ioreq_server.lock);
> +    s = get_ioreq_server(d, id);
> +    if ( !s )
> +    {
> +        rc = -ENOENT;
> +        goto out;
> +    }
> +    if ( !s->internal )
> +    {
> +        rc = -EINVAL;
> +        goto out;
> +    }
> +    if ( s->handler != NULL )
> +    {
> +        rc = -EBUSY;
> +        goto out;
> +    }
> +
> +    s->handler = handler;
> +
> + out:
> +    spin_unlock_recursive(&d->arch.hvm.ioreq_server.lock);
> +
> +    return rc;
> +}
> +
>  static void hvm_update_ioreq_evtchn(struct hvm_ioreq_server *s,
>                                      struct hvm_ioreq_vcpu *sv)
>  {
> diff --git a/xen/include/asm-x86/hvm/ioreq.h b/xen/include/asm-x86/hvm/ioreq.h
> index e8119b26a6..2131c944d4 100644
> --- a/xen/include/asm-x86/hvm/ioreq.h
> +++ b/xen/include/asm-x86/hvm/ioreq.h
> @@ -55,6 +55,9 @@ unsigned int hvm_broadcast_ioreq(ioreq_t *p, bool buffered);
> 
>  void hvm_ioreq_init(struct domain *d);
> 
> +int hvm_add_ioreq_handler(struct domain *d, ioservid_t id,
> +                          int (*handler)(struct vcpu *v, ioreq_t *));
> +
>  #endif /* __ASM_X86_HVM_IOREQ_H__ */
> 
>  /*
> --
> 2.22.0

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