Re: [PATCH v3 for-5.2 3/3] spapr/xive: Convert KVM device fd checks to assert()

[Cédric Le Goater]

On 8/7/20 1:32 PM, Greg Kurz wrote:
> All callers guard these functions with an xive_in_kernel() helper. Make
> it clear that they are only to be called when the KVM XIVE device exists.
> 
> Note that the check on xive is dropped in kvmppc_xive_disconnect(). It
> really cannot be NULL since it comes from set_active_intc() which only
> passes pointers to allocated objects.
> 
> Signed-off-by: Greg Kurz <groug@kaod.org>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

Reviewed-by: Cédric Le Goater <clg@kaod.org>

> ---
> v2: Take the helper name change into account in the changelog
> ---
>  hw/intc/spapr_xive_kvm.c |   35 +++++++----------------------------
>  1 file changed, 7 insertions(+), 28 deletions(-)
> 
> diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> index 6130882be678..82a6f99f022d 100644
> --- a/hw/intc/spapr_xive_kvm.c
> +++ b/hw/intc/spapr_xive_kvm.c
> @@ -79,10 +79,7 @@ void kvmppc_xive_cpu_set_state(XiveTCTX *tctx, Error 
> **errp)
>      uint64_t state[2];
>      int ret;
>  
> -    /* The KVM XIVE device is not in use yet */
> -    if (xive->fd == -1) {
> -        return;
> -    }
> +    assert(xive->fd != -1);
>  
>      /* word0 and word1 of the OS ring. */
>      state[0] = *((uint64_t *) &tctx->regs[TM_QW1_OS]);
> @@ -101,10 +98,7 @@ void kvmppc_xive_cpu_get_state(XiveTCTX *tctx, Error 
> **errp)
>      uint64_t state[2] = { 0 };
>      int ret;
>  
> -    /* The KVM XIVE device is not in use */
> -    if (xive->fd == -1) {
> -        return;
> -    }
> +    assert(xive->fd != -1);
>  
>      ret = kvm_get_one_reg(tctx->cs, KVM_REG_PPC_VP_STATE, state);
>      if (ret != 0) {
> @@ -156,10 +150,7 @@ void kvmppc_xive_cpu_connect(XiveTCTX *tctx, Error 
> **errp)
>      unsigned long vcpu_id;
>      int ret;
>  
> -    /* The KVM XIVE device is not in use */
> -    if (xive->fd == -1) {
> -        return;
> -    }
> +    assert(xive->fd != -1);
>  
>      /* Check if CPU was hot unplugged and replugged. */
>      if (kvm_cpu_is_enabled(tctx->cs)) {
> @@ -245,10 +236,7 @@ int kvmppc_xive_source_reset_one(XiveSource *xsrc, int 
> srcno, Error **errp)
>      SpaprXive *xive = SPAPR_XIVE(xsrc->xive);
>      uint64_t state = 0;
>  
> -    /* The KVM XIVE device is not in use */
> -    if (xive->fd == -1) {
> -        return -ENODEV;
> -    }
> +    assert(xive->fd != -1);
>  
>      if (xive_source_irq_is_lsi(xsrc, srcno)) {
>          state |= KVM_XIVE_LEVEL_SENSITIVE;
> @@ -592,10 +580,7 @@ static void kvmppc_xive_change_state_handler(void 
> *opaque, int running,
>  
>  void kvmppc_xive_synchronize_state(SpaprXive *xive, Error **errp)
>  {
> -    /* The KVM XIVE device is not in use */
> -    if (xive->fd == -1) {
> -        return;
> -    }
> +    assert(xive->fd != -1);
>  
>      /*
>       * When the VM is stopped, the sources are masked and the previous
> @@ -622,10 +607,7 @@ int kvmppc_xive_pre_save(SpaprXive *xive)
>  {
>      Error *local_err = NULL;
>  
> -    /* The KVM XIVE device is not in use */
> -    if (xive->fd == -1) {
> -        return 0;
> -    }
> +    assert(xive->fd != -1);
>  
>      /* EAT: there is no extra state to query from KVM */
>  
> @@ -845,10 +827,7 @@ void kvmppc_xive_disconnect(SpaprInterruptController 
> *intc)
>      XiveSource *xsrc;
>      size_t esb_len;
>  
> -    /* The KVM XIVE device is not in use */
> -    if (!xive || xive->fd == -1) {
> -        return;
> -    }
> +    assert(xive->fd != -1);
>  
>      /* Clear the KVM mapping */
>      xsrc = &xive->source;
> 
>