[Xen-devel] [PATCH 05/14] x86/p2m: Don't overwrite p2m_altp2m_lazy_copy()'s callers p2m pointer

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The final parameter to p2m_altp2m_lazy_copy() appears to be unnecessary, and
results in very hard-to-follow code.  Have the sole caller set its local p2m
pointer appropriately, and drop the parameter.

With that done, a level of indirection of ap2m can be dropped inside
p2m_altp2m_lazy_copy().  While changing the API, switch it from bool_t to
bool, and drop printing of the altp2m's virtual address, because it is of no
use even when debugging.

No (intended) overall change in behaviour.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
--
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>
CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c    |  4 +++-
 xen/arch/x86/mm/p2m.c     | 24 ++++++++++++------------
 xen/include/asm-x86/p2m.h |  4 ++--
 3 files changed, 17 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index e2e4204..94fe441 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1760,7 +1760,9 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long 
gla,
 
     if ( ap2m_active )
     {
-        if ( p2m_altp2m_lazy_copy(curr, gpa, gla, npfec, &p2m) )
+        p2m = p2m_get_altp2m(curr);
+
+        if ( p2m_altp2m_lazy_copy(curr, gpa, gla, npfec) )
         {
             /* entry was lazily copied from host -- retry */
             __put_gfn(hostp2m, gfn);
diff --git a/xen/arch/x86/mm/p2m.c b/xen/arch/x86/mm/p2m.c
index ae9cb20..8b9898a 100644
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -2172,23 +2172,23 @@ bool_t p2m_switch_vcpu_altp2m_by_id(struct vcpu *v, 
unsigned int idx)
  *     indicate that outer handler should handle fault
  */
 
-bool_t p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
-                            unsigned long gla, struct npfec npfec,
-                            struct p2m_domain **ap2m)
+bool p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
+                          unsigned long gla, struct npfec npfec)
 {
     struct p2m_domain *hp2m = p2m_get_hostp2m(v->domain);
+    struct p2m_domain *ap2m = p2m_get_altp2m(v);
     p2m_type_t p2mt;
     p2m_access_t p2ma;
     unsigned int page_order;
-    gfn_t gfn = _gfn(paddr_to_pfn(gpa));
+    gfn_t gfn = gaddr_to_gfn(gpa);
     unsigned long mask;
     mfn_t mfn;
     int rv;
     bool ret;
 
-    *ap2m = p2m_get_altp2m(v);
+    ASSERT(p2m_locked_by_me(hp2m));
 
-    mfn = get_gfn_type_access(*ap2m, gfn_x(gfn), &p2mt, &p2ma,
+    mfn = get_gfn_type_access(ap2m, gfn_x(gfn), &p2mt, &p2ma,
                               0, &page_order);
 
     /* Entry already present in ap2m?  Caller should handle the fault. */
@@ -2216,15 +2216,15 @@ bool_t p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
     mfn = _mfn(mfn_x(mfn) & mask);
     gfn = _gfn(gfn_x(gfn) & mask);
 
-    p2m_lock(*ap2m);
-    rv = p2m_set_entry(*ap2m, gfn, mfn, page_order, p2mt, p2ma);
-    p2m_unlock(*ap2m);
+    p2m_lock(ap2m);
+    rv = p2m_set_entry(ap2m, gfn, mfn, page_order, p2mt, p2ma);
+    p2m_unlock(ap2m);
 
     if ( rv )
     {
         gdprintk(XENLOG_ERR,
-           "failed to set entry for %#"PRIx64" -> %#"PRIx64" p2m %#"PRIx64"\n",
-           gfn_x(gfn), mfn_x(mfn), (unsigned long)*ap2m);
+           "failed to set entry for %#"PRIx64" -> %#"PRIx64"\n",
+           gfn_x(gfn), mfn_x(mfn));
         domain_crash(hp2m->domain);
     }
 
@@ -2233,7 +2233,7 @@ bool_t p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
 put_hp2m:
     __put_gfn(hp2m, gfn_x(gfn));
 put_ap2m:
-    __put_gfn(*ap2m, gfn_x(gfn));
+    __put_gfn(ap2m, gfn_x(gfn));
 
     return ret;
 }
diff --git a/xen/include/asm-x86/p2m.h b/xen/include/asm-x86/p2m.h
index 6d849a5..04c2104 100644
--- a/xen/include/asm-x86/p2m.h
+++ b/xen/include/asm-x86/p2m.h
@@ -868,8 +868,8 @@ void p2m_altp2m_check(struct vcpu *v, uint16_t idx);
 void p2m_flush_altp2m(struct domain *d);
 
 /* Alternate p2m paging */
-bool_t p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
-    unsigned long gla, struct npfec npfec, struct p2m_domain **ap2m);
+bool p2m_altp2m_lazy_copy(struct vcpu *v, paddr_t gpa,
+                          unsigned long gla, struct npfec npfec);
 
 /* Make a specific alternate p2m valid */
 int p2m_init_altp2m_by_id(struct domain *d, unsigned int idx);
-- 
2.1.4


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