0303-p2m-pt-Avoid-hard-coding-Xen-s-PAT.patch

From 1ca8af08dfa46a8b3c376e0bd1b74ccde579f48d Mon Sep 17 00:00:00 2001
From: Demi Marie Obenour <demi@invisiblethingslab.com>
Date: Thu, 15 Dec 2022 17:03:45 +0100
Subject: [PATCH 3/9] p2m-pt: Avoid hard-coding Xen's PAT
To: xen-devel@lists.xenproject.org
Cc: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>,
    Jan Beulich <jbeulich@suse.com>,
    Andrew Cooper <andrew.cooper3@citrix.com>,
    "Roger Pau Monné" <roger.pau@citrix.com>,
    Wei Liu <wl@xen.org>,
    Jun Nakajima <jun.nakajima@intel.com>,
    Kevin Tian <kevin.tian@intel.com>,
    George Dunlap <george.dunlap@citrix.com>,
    Tim Deegan <tim@xen.org>

This makes the code much easier to understand.  No functional change
intended.  As per Andrew Cooper, the existing logic is questionable, but
this does not make it any worse.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
 xen/arch/x86/mm/p2m-pt.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/mm/p2m-pt.c b/xen/arch/x86/mm/p2m-pt.c
index eaba2b0fb4e6830f52b7d112fba8175dfe6d2770..cd1af33b6772ab1016e8d4c3284a6bc5d282869d 100644
--- a/xen/arch/x86/mm/p2m-pt.c
+++ b/xen/arch/x86/mm/p2m-pt.c
@@ -99,13 +99,13 @@ static unsigned long p2m_type_to_flags(const struct p2m_domain *p2m,
         return flags | P2M_BASE_FLAGS | _PAGE_RW | _PAGE_NX_BIT;
     case p2m_mmio_direct:
         if ( !rangeset_contains_singleton(mmio_ro_ranges, mfn_x(mfn)) )
-            flags |= _PAGE_RW;
+            flags |= _PAGE_RW | _PAGE_UCM;
         else
         {
-            flags |= _PAGE_PWT;
+            flags |= _PAGE_UC;
             ASSERT(!level);
         }
-        return flags | P2M_BASE_FLAGS | _PAGE_PCD;
+        return flags | P2M_BASE_FLAGS;
     }
 }
 
-- 
Sincerely,
Demi Marie Obenour (she/her/hers)
Invisible Things Lab