[Xen-devel] [PATCH V6 4/4] x86/mm: Make use of the default access param from xc_altp2m_create_view

[Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>]

At this moment the default_access param from xc_altp2m_create_view is
not used.

This patch assigns default_access to p2m->default_access at the time of
initializing a new altp2m view.

Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
---
CC: Jan Beulich <jbeulich@xxxxxxxx>
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: "Roger Pau Monné" <roger.pau@xxxxxxxxxx>
CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
CC: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
CC: Julien Grall <julien@xxxxxxx>
CC: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
CC: Stefano Stabellini <sstabellini@xxxxxxxxxx>
CC: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
CC: Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
Changes since V4:
        - Add const struct p2m_domain *p2m to
xenmem_access_to_p2m_access()
        - Pull xenmem_access_to_p2m_access() out of the locked area
        - Add a check for NULL p2m in xenmem_access_to_p2m_access().
---
 xen/arch/x86/hvm/hvm.c          |  3 ++-
 xen/arch/x86/mm/mem_access.c    | 11 +++++++----
 xen/arch/x86/mm/p2m.c           | 21 ++++++++++++++++-----
 xen/include/asm-x86/p2m.h       |  3 ++-
 xen/include/public/hvm/hvm_op.h |  2 --
 xen/include/xen/mem_access.h    |  4 ++++
 6 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 4db15768d4..678faa4b14 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4660,7 +4660,8 @@ static int do_altp2m_op(
     }
 
     case HVMOP_altp2m_create_p2m:
-        if ( !(rc = p2m_init_next_altp2m(d, &a.u.view.view)) )
+        if ( !(rc = p2m_init_next_altp2m(d, &a.u.view.view,
+                                         a.u.view.hvmmem_default_access)) )
             rc = __copy_to_guest(arg, &a, 1) ? -EFAULT : 0;
         break;
 
diff --git a/xen/arch/x86/mm/mem_access.c b/xen/arch/x86/mm/mem_access.c
index a95a50bcae..80de6c2c65 100644
--- a/xen/arch/x86/mm/mem_access.c
+++ b/xen/arch/x86/mm/mem_access.c
@@ -314,9 +314,9 @@ static int set_mem_access(struct domain *d, struct 
p2m_domain *p2m,
     return rc;
 }
 
-static bool xenmem_access_to_p2m_access(struct p2m_domain *p2m,
-                                        xenmem_access_t xaccess,
-                                        p2m_access_t *paccess)
+bool xenmem_access_to_p2m_access(const struct p2m_domain *p2m,
+                                 xenmem_access_t xaccess,
+                                 p2m_access_t *paccess)
 {
     static const p2m_access_t memaccess[] = {
 #define ACCESS(ac) [XENMEM_access_##ac] = p2m_access_##ac
@@ -340,7 +340,10 @@ static bool xenmem_access_to_p2m_access(struct p2m_domain 
*p2m,
         *paccess = memaccess[xaccess];
         break;
     case XENMEM_access_default:
-        *paccess = p2m->default_access;
+        if ( !p2m )
+            *paccess = p2m_access_rwx;
+        else
+            *paccess = p2m->default_access;
         break;
     default:
         return false;
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index 5b99d1eb97..926438ed64 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -25,6 +25,7 @@
 
 #include <xen/guest_access.h> /* copy_from_guest() */
 #include <xen/iommu.h>
+#include <xen/mem_access.h>
 #include <xen/vm_event.h>
 #include <xen/event.h>
 #include <public/vm_event.h>
@@ -2536,7 +2537,8 @@ void p2m_flush_altp2m(struct domain *d)
     altp2m_list_unlock(d);
 }
 
-static int p2m_activate_altp2m(struct domain *d, unsigned int idx)
+static int p2m_activate_altp2m(struct domain *d, unsigned int idx,
+                               p2m_access_t hvmmem_default_access)
 {
     struct p2m_domain *hostp2m, *p2m;
     int rc;
@@ -2562,7 +2564,7 @@ static int p2m_activate_altp2m(struct domain *d, unsigned 
int idx)
         goto out;
     }
 
-    p2m->default_access = hostp2m->default_access;
+    p2m->default_access = hvmmem_default_access;
     p2m->domain = hostp2m->domain;
     p2m->global_logdirty = hostp2m->global_logdirty;
     p2m->min_remapped_gfn = gfn_x(INVALID_GFN);
@@ -2579,6 +2581,7 @@ static int p2m_activate_altp2m(struct domain *d, unsigned 
int idx)
 int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx)
 {
     int rc = -EINVAL;
+    struct p2m_domain *hostp2m = p2m_get_hostp2m(d);
 
     if ( idx >= MAX_ALTP2M )
         return rc;
@@ -2588,16 +2591,23 @@ int p2m_init_altp2m_by_id(struct domain *d, unsigned 
int idx)
     altp2m_list_lock(d);
 
     if ( d->arch.altp2m_eptp[idx] == mfn_x(INVALID_MFN) )
-        rc = p2m_activate_altp2m(d, idx);
+        rc = p2m_activate_altp2m(d, idx, hostp2m->default_access);
 
     altp2m_list_unlock(d);
     return rc;
 }
 
-int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
+int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,
+                         xenmem_access_t hvmmem_default_access)
 {
     int rc = -EINVAL;
     unsigned int i;
+    p2m_access_t a;
+    struct p2m_domain *p2m;
+
+    if ( hvmmem_default_access > XENMEM_access_default ||
+         !xenmem_access_to_p2m_access(NULL, hvmmem_default_access, &a) )
+        return rc;
 
     altp2m_list_lock(d);
 
@@ -2606,7 +2616,8 @@ int p2m_init_next_altp2m(struct domain *d, uint16_t *idx)
         if ( d->arch.altp2m_eptp[i] != mfn_x(INVALID_MFN) )
             continue;
 
-        rc = p2m_activate_altp2m(d, i);
+        p2m = d->arch.altp2m_p2m[i];
+        rc = p2m_activate_altp2m(d, i, a);
 
         if ( !rc )
             *idx = i;
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 94285db1b4..ac2d2787f4 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -884,7 +884,8 @@ bool p2m_altp2m_get_or_propagate(struct p2m_domain *ap2m, 
unsigned long gfn_l,
 int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx);
 
 /* Find an available alternate p2m and make it valid */
-int p2m_init_next_altp2m(struct domain *d, uint16_t *idx);
+int p2m_init_next_altp2m(struct domain *d, uint16_t *idx,
+                         xenmem_access_t hvmmem_default_access);
 
 /* Make a specific alternate p2m invalid */
 int p2m_destroy_altp2m_by_id(struct domain *d, unsigned int idx);
diff --git a/xen/include/public/hvm/hvm_op.h b/xen/include/public/hvm/hvm_op.h
index 1f049cfa2e..bb98abec88 100644
--- a/xen/include/public/hvm/hvm_op.h
+++ b/xen/include/public/hvm/hvm_op.h
@@ -251,8 +251,6 @@ 
DEFINE_XEN_GUEST_HANDLE(xen_hvm_altp2m_vcpu_disable_notify_t);
 struct xen_hvm_altp2m_view {
     /* IN/OUT variable */
     uint16_t view;
-    /* Create view only: default access type
-     * NOTE: currently ignored */
     uint16_t hvmmem_default_access; /* xenmem_access_t */
 };
 typedef struct xen_hvm_altp2m_view xen_hvm_altp2m_view_t;
diff --git a/xen/include/xen/mem_access.h b/xen/include/xen/mem_access.h
index 00e594a0ad..5d53fb8ce4 100644
--- a/xen/include/xen/mem_access.h
+++ b/xen/include/xen/mem_access.h
@@ -58,6 +58,10 @@ typedef enum {
     /* NOTE: Assumed to be only 4 bits right now on x86. */
 } p2m_access_t;
 
+bool xenmem_access_to_p2m_access(const struct p2m_domain *p2m,
+                                 xenmem_access_t xaccess,
+                                 p2m_access_t *paccess);
+
 /*
  * Set access type for a region of gfns.
  * If gfn == INVALID_GFN, sets the default access type.
-- 
2.17.1

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