[Xen-devel] [PATCH] x86/HVM: drop bogus #PF raising from linear->phys translation

["Jan Beulich" <JBeulich@xxxxxxxx>]

Translations spanning a page boundary not resulting in physically
contiguous addresses is not a reason to raise #PF. In fact by not doing
so accesses of this kind are being emulated correctly thanks to the
fallback logic in the insn emulator's REP MOVS/STOS/INS/OUTS handling
(non-string accesses to such locations are being split elsewhere and
hence have been working fine already).

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -566,15 +566,12 @@ static int hvmemul_linear_to_phys(
             if ( pfec & (PFEC_page_paged | PFEC_page_shared) )
                 return X86EMUL_RETRY;
             done /= bytes_per_rep;
-            *reps = done;
             if ( done == 0 )
             {
                 ASSERT(!reverse);
-                if ( npfn != gfn_x(INVALID_GFN) )
-                    return X86EMUL_UNHANDLEABLE;
-                x86_emul_pagefault(pfec, addr & PAGE_MASK, 
&hvmemul_ctxt->ctxt);
-                return X86EMUL_EXCEPTION;
+                return X86EMUL_UNHANDLEABLE;
             }
+            *reps = done;
             break;
         }
 




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