First of all using is_idle_domain() on the subject domain in the body of
for_each_domain() is pointless. Replace that conditional by one checking
that a domain actually has IOMMU support enabled for it, and that we're
actually on a VT-d system (both are largely cosmetic / documentary with
how things work elsewhere, but still).

Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/tboot.c
+++ b/xen/arch/x86/tboot.c
@@ -31,6 +31,8 @@ static vmac_t frametable_mac; /* MAC for
 static uint64_t __initdata txt_heap_base, __initdata txt_heap_size;
 static uint64_t __initdata sinit_base, __initdata sinit_size;
 
+static bool __ro_after_init is_vtd;
+
 /*
  * TXT configuration registers (offsets from TXT_{PUB, PRIV}_CONFIG_REGS_BASE)
  */
@@ -201,7 +203,7 @@ static void tboot_gen_domain_integrity(c
         }
         spin_unlock(&d->page_alloc_lock);
 
-        if ( !is_idle_domain(d) )
+        if ( is_iommu_enabled(d) && is_vtd )
         {
             const struct domain_iommu *dio = dom_iommu(d);
 
@@ -444,6 +446,8 @@ int __init cf_check tboot_parse_dmar_tab
     if ( txt_heap_base == 0 )
         return 1;
 
+    is_vtd = true;
+
     /* walk heap to SinitMleData */
     pa = txt_heap_base;
     /* skip BiosData */

On 06/12/2022 13:56, Jan Beulich wrote:
> First of all using is_idle_domain() on the subject domain in the body of
> for_each_domain() is pointless. Replace that conditional by one checking
> that a domain actually has IOMMU support enabled for it, and that we're
> actually on a VT-d system (both are largely cosmetic / documentary with
> how things work elsewhere, but still).
>
> Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

On Tue, Dec 6, 2022 at 8:57 AM Jan Beulich <jbeulich@suse.com> wrote:
>
> First of all using is_idle_domain() on the subject domain in the body of
> for_each_domain() is pointless. Replace that conditional by one checking
> that a domain actually has IOMMU support enabled for it, and that we're
> actually on a VT-d system (both are largely cosmetic / documentary with
> how things work elsewhere, but still).
>
> Reported-by: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Jason Andryuk <jandryuk@gmail.com>