[PATCH v2 1/2] x86/mem_access: Add a helper function for memaccess conversion

From: Adrian Pop <apop@bitdefender.com>
To: xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Razvan Cojocaru <rcojocaru@bitdefender.com>,
	George Dunlap <george.dunlap@eu.citrix.com>,
	Andrew Cooper <andrew.cooper3@citrix.com>,
	Adrian Pop <apop@bitdefender.com>,
	Ian Jackson <ian.jackson@eu.citrix.com>, Tim Deegan <tim@xen.org>,
	Julien Grall <julien.grall@arm.com>,
	Tamas K Lengyel <tamas@tklengyel.com>,
	Jan Beulich <jbeulich@suse.com>
Subject: [PATCH v2 1/2] x86/mem_access: Add a helper function for memaccess conversion
Date: Thu,  5 Jul 2018 13:44:44 +0300	[thread overview]
Message-ID: <20180705104445.8048-2-apop@bitdefender.com> (raw)
In-Reply-To: <20180705104445.8048-1-apop@bitdefender.com>

The p2m_access_to_xenmem_access() converts a p2m_access_t to a
xenmem_access_t.  It is complementary to xenmem_access_to_p2m_access().
It is currently only used by _p2m_get_mem_access().

Signed-off-by: Adrian Pop <apop@bitdefender.com>
---
 xen/arch/x86/mm/mem_access.c | 41 +++++++++++++++++++++---------------
 1 file changed, 24 insertions(+), 17 deletions(-)

diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index c0cd0174cf..e75ff0c735 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -33,16 +33,12 @@
 #include "mm-locks.h"
 
 /*
- * Get access type for a gfn.
- * If gfn == INVALID_GFN, gets the default access type.
+ * Convert a p2m_access_t to a xenmem_access_t.
  */
-static int _p2m_get_mem_access(struct p2m_domain *p2m, gfn_t gfn,
-                               xenmem_access_t *access)
+static int p2m_access_to_xenmem_access(struct p2m_domain *p2m,
+                                       p2m_access_t paccess,
+                                       xenmem_access_t *xaccess)
 {
-    p2m_type_t t;
-    p2m_access_t a;
-    mfn_t mfn;
-
     static const xenmem_access_t memaccess[] = {
 #define ACCESS(ac) [p2m_access_##ac] = XENMEM_access_##ac
             ACCESS(n),
@@ -58,12 +54,27 @@ static int _p2m_get_mem_access(struct p2m_domain *p2m, gfn_t gfn,
 #undef ACCESS
     };
 
+    if ( (unsigned int)paccess >= ARRAY_SIZE(memaccess) )
+        return -ERANGE;
+
+    *xaccess = memaccess[paccess];
+    return 0;
+}
+
+/*
+ * Get access type for a gfn.
+ * If gfn == INVALID_GFN, gets the default access type.
+ */
+static int _p2m_get_mem_access(struct p2m_domain *p2m, gfn_t gfn,
+                               xenmem_access_t *access)
+{
+    p2m_type_t t;
+    p2m_access_t a;
+    mfn_t mfn;
+
     /* If request to get default access. */
     if ( gfn_eq(gfn, INVALID_GFN) )
-    {
-        *access = memaccess[p2m->default_access];
-        return 0;
-    }
+        return p2m_access_to_xenmem_access(p2m, p2m->default_access, access);
 
     gfn_lock(p2m, gfn, 0);
     mfn = p2m->get_entry(p2m, gfn, &t, &a, 0, NULL, NULL);
@@ -72,11 +83,7 @@ static int _p2m_get_mem_access(struct p2m_domain *p2m, gfn_t gfn,
     if ( mfn_eq(mfn, INVALID_MFN) )
         return -ESRCH;
 
-    if ( (unsigned int)a >= ARRAY_SIZE(memaccess) )
-        return -ERANGE;
-
-    *access =  memaccess[a];
-    return 0;
+    return access_to_xenmem_access(p2m, a, access);
 }
 
 bool p2m_mem_access_emulate_check(struct vcpu *v,
-- 
2.17.0


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