The variables iommu_enabled and iommu_dont_flush_iotlb are defined in
drivers/passthrough/iommu.c and are referenced in common code, which
causes the link to fail when !CONFIG_HAS_PASSTHROUGH.

Guard references to these variables in common code so that xen
builds when !CONFIG_HAS_PASSTHROUGH.

Signed-off-by: Connor Davis <connojdavis@gmail.com>
---
 xen/common/domain.c |  2 ++
 xen/common/memory.c | 10 ++++++++++
 xen/common/sysctl.c |  2 ++
 3 files changed, 14 insertions(+)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index d85984638a..ad66bca325 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -501,7 +501,9 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
             return -EINVAL;
         }
 
+#ifdef CONFIG_HAS_PASSTHROUGH
         if ( !iommu_enabled )
+#endif
         {
             dprintk(XENLOG_INFO, "IOMMU requested but not available\n");
             return -EINVAL;
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 76b9f58478..7135324857 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -294,7 +294,9 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
     p2m_type_t p2mt;
 #endif
     mfn_t mfn;
+#ifdef CONFIG_HAS_PASSTHROUGH
     bool *dont_flush_p, dont_flush;
+#endif
     int rc;
 
 #ifdef CONFIG_X86
@@ -385,13 +387,17 @@ int guest_remove_page(struct domain *d, unsigned long gmfn)
      * Since we're likely to free the page below, we need to suspend
      * xenmem_add_to_physmap()'s suppressing of IOMMU TLB flushes.
      */
+#ifdef CONFIG_HAS_PASSTHROUGH
     dont_flush_p = &this_cpu(iommu_dont_flush_iotlb);
     dont_flush = *dont_flush_p;
     *dont_flush_p = false;
+#endif
 
     rc = guest_physmap_remove_page(d, _gfn(gmfn), mfn, 0);
 
+#ifdef CONFIG_HAS_PASSTHROUGH
     *dont_flush_p = dont_flush;
+#endif
 
     /*
      * With the lack of an IOMMU on some platforms, domains with DMA-capable
@@ -839,11 +845,13 @@ int xenmem_add_to_physmap(struct domain *d, struct xen_add_to_physmap *xatp,
     xatp->gpfn += start;
     xatp->size -= start;
 
+#ifdef CONFIG_HAS_PASSTHROUGH
     if ( is_iommu_enabled(d) )
     {
        this_cpu(iommu_dont_flush_iotlb) = 1;
        extra.ppage = &pages[0];
     }
+#endif
 
     while ( xatp->size > done )
     {
@@ -868,6 +876,7 @@ int xenmem_add_to_physmap(struct domain *d, struct xen_add_to_physmap *xatp,
         }
     }
 
+#ifdef CONFIG_HAS_PASSTHROUGH
     if ( is_iommu_enabled(d) )
     {
         int ret;
@@ -894,6 +903,7 @@ int xenmem_add_to_physmap(struct domain *d, struct xen_add_to_physmap *xatp,
         if ( unlikely(ret) && rc >= 0 )
             rc = ret;
     }
+#endif
 
     return rc;
 }
diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index 3558641cd9..b4dde7bef6 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -271,12 +271,14 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
         pi->cpu_khz = cpu_khz;
         pi->max_mfn = get_upper_mfn_bound();
         arch_do_physinfo(pi);
+#ifdef CONFIG_HAS_PASSTHROUGH
         if ( iommu_enabled )
         {
             pi->capabilities |= XEN_SYSCTL_PHYSCAP_directio;
             if ( iommu_hap_pt_share )
                 pi->capabilities |= XEN_SYSCTL_PHYSCAP_iommu_hap_pt_share;
         }
+#endif
         if ( vmtrace_available )
             pi->capabilities |= XEN_SYSCTL_PHYSCAP_vmtrace;
 
-- 
2.27.0

On 25.02.2021 16:24, Connor Davis wrote:
> --- a/xen/common/domain.c
> +++ b/xen/common/domain.c
> @@ -501,7 +501,9 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
>              return -EINVAL;
>          }
>  
> +#ifdef CONFIG_HAS_PASSTHROUGH
>          if ( !iommu_enabled )
> +#endif
>          {
>              dprintk(XENLOG_INFO, "IOMMU requested but not available\n");
>              return -EINVAL;

Where possible - to avoid such #ifdef-ary - the symbol instead should
get #define-d to a sensible value ("false" in this case) in the header.
The other cases here may indeed need to remain as you have them.

Jan

On Thu, Feb 25, 2021 at 04:45:15PM +0100, Jan Beulich wrote:
> On 25.02.2021 16:24, Connor Davis wrote:
> > --- a/xen/common/domain.c
> > +++ b/xen/common/domain.c
> > @@ -501,7 +501,9 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
> >              return -EINVAL;
> >          }
> >  
> > +#ifdef CONFIG_HAS_PASSTHROUGH
> >          if ( !iommu_enabled )
> > +#endif
> >          {
> >              dprintk(XENLOG_INFO, "IOMMU requested but not available\n");
> >              return -EINVAL;
> 
> Where possible - to avoid such #ifdef-ary - the symbol instead should
> get #define-d to a sensible value ("false" in this case) in the header.
> The other cases here may indeed need to remain as you have them.
> 
Do you prefer the #define in the same function near the if or
somwhere near the top of the file?

Connor

On 26.02.2021 03:54, Connor Davis wrote:
> On Thu, Feb 25, 2021 at 04:45:15PM +0100, Jan Beulich wrote:
>> On 25.02.2021 16:24, Connor Davis wrote:
>>> --- a/xen/common/domain.c
>>> +++ b/xen/common/domain.c
>>> @@ -501,7 +501,9 @@ static int sanitise_domain_config(struct xen_domctl_createdomain *config)
>>>              return -EINVAL;
>>>          }
>>>  
>>> +#ifdef CONFIG_HAS_PASSTHROUGH
>>>          if ( !iommu_enabled )
>>> +#endif
>>>          {
>>>              dprintk(XENLOG_INFO, "IOMMU requested but not available\n");
>>>              return -EINVAL;
>>
>> Where possible - to avoid such #ifdef-ary - the symbol instead should
>> get #define-d to a sensible value ("false" in this case) in the header.
>> The other cases here may indeed need to remain as you have them.
>>
> Do you prefer the #define in the same function near the if or
> somwhere near the top of the file?

Neither, if I understand you correctly. It should be in the same header
where the extern declaration lives, for the whole code base to consume.

Jan