x86/HVM: honor cache attribute pinning for RAM only

Call hvm_get_mem_pinned_cacheattr() for RAM ranges only, and only when
the guest has a physical device assigned: XEN_DOMCTL_pin_mem_cacheattr
is documented to be intended for RAM only.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -782,32 +782,29 @@ int epte_get_entry_emt(struct domain *d,
                                  mfn_x(mfn) + (1UL << order) - 1) )
         return -1;
 
-    switch ( hvm_get_mem_pinned_cacheattr(d, gfn, order, &type) )
+    if ( direct_mmio )
     {
-    case 1:
+        if ( (mfn_x(mfn) ^ d->arch.hvm_domain.vmx.apic_access_mfn) >> order )
+            return MTRR_TYPE_UNCACHABLE;
+        if ( order )
+            return -1;
         *ipat = 1;
-        return type != PAT_TYPE_UC_MINUS ? type : PAT_TYPE_UNCACHABLE;
-    case -1:
-        return -1;
+        return MTRR_TYPE_WRBACK;
     }
 
     if ( !need_iommu(d) && !cache_flush_permitted(d) )
     {
-        ASSERT(!direct_mmio ||
-               !((mfn_x(mfn) ^ d->arch.hvm_domain.vmx.apic_access_mfn) >>
-                 order));
         *ipat = 1;
         return MTRR_TYPE_WRBACK;
     }
 
-    if ( direct_mmio )
+    switch ( hvm_get_mem_pinned_cacheattr(d, gfn, order, &type) )
     {
-        if ( (mfn_x(mfn) ^ d->arch.hvm_domain.vmx.apic_access_mfn) >> order )
-            return MTRR_TYPE_UNCACHABLE;
-        if ( order )
-            return -1;
+    case 1:
         *ipat = 1;
-        return MTRR_TYPE_WRBACK;
+        return type != PAT_TYPE_UC_MINUS ? type : PAT_TYPE_UNCACHABLE;
+    case -1:
+        return -1;
     }
 
     gmtrr_mtype = is_hvm_domain(d) && v ?
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -618,7 +618,8 @@ _sh_propagate(struct vcpu *v,
          * 3) if disables snoop control, compute the PAT index with
          *    gMTRR and gPAT.
          */
-        if ( hvm_get_mem_pinned_cacheattr(d, gfn_x(target_gfn), 0, &type) )
+        if ( !mmio_mfn &&
+             hvm_get_mem_pinned_cacheattr(d, gfn_x(target_gfn), 0, &type) )
             sflags |= pat_type_2_pte_flags(type);
         else if ( d->arch.hvm_domain.is_in_uc_mode )
             sflags |= pat_type_2_pte_flags(PAT_TYPE_UNCACHABLE);