[Xen-devel] [PATCH v2 2/4] x86/shadow: Drop shadow_mode_trap_reads()

[Tim Deegan <tim@xxxxxxx>]

This was never actually implemented, and is confusing coverity.

Coverity CID 1090354

Signed-off-by: Tim Deegan <tim@xxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c | 30 ++++--------------------------
 xen/include/asm-x86/shadow.h   |  4 ----
 2 files changed, 4 insertions(+), 30 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index 3d35537..5c7a7ac 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -692,21 +692,7 @@ _sh_propagate(struct vcpu *v,
                        && (ft == ft_demand_write))
 #endif /* OOS */
                   ) )
-    {
-        if ( shadow_mode_trap_reads(d) )
-        {
-            // if we are trapping both reads & writes, then mark this page
-            // as not present...
-            //
-            sflags &= ~_PAGE_PRESENT;
-        }
-        else
-        {
-            // otherwise, just prevent any writes...
-            //
-            sflags &= ~_PAGE_RW;
-        }
-    }
+        sflags &= ~_PAGE_RW;
 
     // PV guests in 64-bit mode use two different page tables for user vs
     // supervisor permissions, making the guest's _PAGE_USER bit irrelevant.
@@ -3181,18 +3167,10 @@ static int sh_page_fault(struct vcpu *v,
          && !(mfn_is_out_of_sync(gmfn)
               && !(regs->error_code & PFEC_user_mode))
 #endif
-         )
+         && (ft == ft_demand_write) )
     {
-        if ( ft == ft_demand_write )
-        {
-            perfc_incr(shadow_fault_emulate_write);
-            goto emulate;
-        }
-        else if ( shadow_mode_trap_reads(d) && ft == ft_demand_read )
-        {
-            perfc_incr(shadow_fault_emulate_read);
-            goto emulate;
-        }
+        perfc_incr(shadow_fault_emulate_write);
+        goto emulate;
     }
 
     /* Need to hand off device-model MMIO to the device model */
diff --git a/xen/include/asm-x86/shadow.h b/xen/include/asm-x86/shadow.h
index 348915e..f40cab4 100644
--- a/xen/include/asm-x86/shadow.h
+++ b/xen/include/asm-x86/shadow.h
@@ -44,10 +44,6 @@
 #define shadow_mode_external(_d)  (paging_mode_shadow(_d) && \
                                    paging_mode_external(_d))
 
-/* Xen traps & emulates all reads of all page table pages:
- * not yet supported */
-#define shadow_mode_trap_reads(_d) ({ (void)(_d); 0; })
-
 /*****************************************************************************
  * Entry points into the shadow code */
 
-- 
1.8.5.2


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