[PATCH V2 08/23] xen/ioreq: Introduce ioreq_params to abstract accesses to arch.hvm.params

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

We don't want to move HVM params field out of *arch.hvm* in this particular
case as although it stores a few IOREQ params, it is not a (completely)
IOREQ stuff and is specific to the architecture. Instead, abstract
accesses by the proposed macro.

This is a follow up action to reduce layering violation in the common code.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
CC: Julien Grall <julien.grall@xxxxxxx>

---
Please note, this is a split/cleanup/hardening of Julien's PoC:
"Add support for Guest IO forwarding to a device emulator"

Changes V1 -> V2:
   - new patch
---
 xen/common/ioreq.c               | 4 ++--
 xen/include/asm-x86/hvm/domain.h | 2 ++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/common/ioreq.c b/xen/common/ioreq.c
index 7f91bc2..a07f1d7 100644
--- a/xen/common/ioreq.c
+++ b/xen/common/ioreq.c
@@ -223,7 +223,7 @@ static gfn_t hvm_alloc_legacy_ioreq_gfn(struct ioreq_server 
*s)
     for ( i = HVM_PARAM_IOREQ_PFN; i <= HVM_PARAM_BUFIOREQ_PFN; i++ )
     {
         if ( !test_and_clear_bit(i, &d->ioreq_gfn.legacy_mask) )
-            return _gfn(d->arch.hvm.params[i]);
+            return _gfn(ioreq_params(d, i));
     }
 
     return INVALID_GFN;
@@ -255,7 +255,7 @@ static bool hvm_free_legacy_ioreq_gfn(struct ioreq_server 
*s,
 
     for ( i = HVM_PARAM_IOREQ_PFN; i <= HVM_PARAM_BUFIOREQ_PFN; i++ )
     {
-        if ( gfn_eq(gfn, _gfn(d->arch.hvm.params[i])) )
+        if ( gfn_eq(gfn, _gfn(ioreq_params(d, i))) )
              break;
     }
     if ( i > HVM_PARAM_BUFIOREQ_PFN )
diff --git a/xen/include/asm-x86/hvm/domain.h b/xen/include/asm-x86/hvm/domain.h
index 5d60737..c3af339 100644
--- a/xen/include/asm-x86/hvm/domain.h
+++ b/xen/include/asm-x86/hvm/domain.h
@@ -63,6 +63,8 @@ struct hvm_pi_ops {
     void (*vcpu_block)(struct vcpu *);
 };
 
+#define ioreq_params(d, i) ((d)->arch.hvm.params[i])
+
 struct hvm_domain {
     /* Cached CF8 for guest PCI config cycles */
     uint32_t                pci_cf8;
-- 
2.7.4