[Xen-devel] [PATCH v3 16/24] x86/emul: Avoid raising faults behind the emulators back

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Introduce a new x86_emul_pagefault() similar to x86_emul_hw_exception(), and
use this instead of hvm_inject_page_fault() from emulation codepaths.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
v2:
 * Change x86_emul_pagefault()'s error_code parameter to being signed
 * Split out shadow changes
---
 xen/arch/x86/hvm/emulate.c             |  4 ++--
 xen/arch/x86/x86_emulate/x86_emulate.h | 13 +++++++++++++
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 4b8c9a0..614e182 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -459,7 +459,7 @@ static int hvmemul_linear_to_phys(
     {
         if ( pfec & (PFEC_page_paged | PFEC_page_shared) )
             return X86EMUL_RETRY;
-        hvm_inject_page_fault(pfec, addr);
+        x86_emul_pagefault(pfec, addr, &hvmemul_ctxt->ctxt);
         return X86EMUL_EXCEPTION;
     }
 
@@ -483,7 +483,7 @@ static int hvmemul_linear_to_phys(
                 ASSERT(!reverse);
                 if ( npfn != gfn_x(INVALID_GFN) )
                     return X86EMUL_UNHANDLEABLE;
-                hvm_inject_page_fault(pfec, addr & PAGE_MASK);
+                x86_emul_pagefault(pfec, addr & PAGE_MASK, 
&hvmemul_ctxt->ctxt);
                 return X86EMUL_EXCEPTION;
             }
             *reps = done;
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h 
b/xen/arch/x86/x86_emulate/x86_emulate.h
index 3c0b25d..8aa4b0b 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.h
+++ b/xen/arch/x86/x86_emulate/x86_emulate.h
@@ -648,6 +648,19 @@ static inline void x86_emul_hw_exception(
     ctxt->event_pending = true;
 }
 
+static inline void x86_emul_pagefault(
+    int error_code, unsigned long cr2, struct x86_emulate_ctxt *ctxt)
+{
+    ASSERT(!ctxt->event_pending);
+
+    ctxt->event.vector = 14; /* TRAP_page_fault */
+    ctxt->event.type = X86_EVENTTYPE_HW_EXCEPTION;
+    ctxt->event.error_code = error_code;
+    ctxt->event.cr2 = cr2;
+
+    ctxt->event_pending = true;
+}
+
 static inline void x86_emul_software_event(
     enum x86_swint_type type, uint8_t vector, uint8_t insn_len,
     struct x86_emulate_ctxt *ctxt)
-- 
2.1.4


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