[Xen-changelog] [xen-unstable] x86 hvm: Emulate RAM-to-RAM REP MOVS copies efficiently.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1219756217 -3600
# Node ID 493a0a87919e4403d88dc716254fbdf646afa2f1
# Parent  62b904dcf88c4549620741fcd16e9b33b53ea289
x86 hvm: Emulate RAM-to-RAM REP MOVS copies efficiently.
Signed-off-by: Keir Fraser <keir.fraser@xxxxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c |   29 ++++++++++++++++++++++-------
 1 files changed, 22 insertions(+), 7 deletions(-)

diff -r 62b904dcf88c -r 493a0a87919e xen/arch/x86/hvm/emulate.c
--- a/xen/arch/x86/hvm/emulate.c        Tue Aug 26 13:00:43 2008 +0100
+++ b/xen/arch/x86/hvm/emulate.c        Tue Aug 26 14:10:17 2008 +0100
@@ -575,7 +575,8 @@ static int hvmemul_rep_movs(
     paddr_t sgpa, dgpa;
     uint32_t pfec = PFEC_page_present;
     p2m_type_t p2mt;
-    int rc;
+    int rc, df = !!(ctxt->regs->eflags & X86_EFLAGS_DF);
+    char *buf;
 
     rc = hvmemul_virtual_to_linear(
         src_seg, src_offset, bytes_per_rep, reps, hvm_access_read,
@@ -606,15 +607,29 @@ static int hvmemul_rep_movs(
     (void)gfn_to_mfn_current(sgpa >> PAGE_SHIFT, &p2mt);
     if ( !p2m_is_ram(p2mt) )
         return hvmemul_do_mmio(
-            sgpa, reps, bytes_per_rep, dgpa, IOREQ_READ,
-            !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL);
+            sgpa, reps, bytes_per_rep, dgpa, IOREQ_READ, df, NULL);
 
     (void)gfn_to_mfn_current(dgpa >> PAGE_SHIFT, &p2mt);
-    if ( p2m_is_ram(p2mt) )
+    if ( !p2m_is_ram(p2mt) )
+        return hvmemul_do_mmio(
+            dgpa, reps, bytes_per_rep, sgpa, IOREQ_WRITE, df, NULL);
+
+    if ( df )
+    {
+        sgpa -= (*reps - 1) * bytes_per_rep;
+        dgpa -= (*reps - 1) * bytes_per_rep;
+    }
+
+    buf = xmalloc_bytes(*reps * bytes_per_rep);
+    if ( buf == NULL )
         return X86EMUL_UNHANDLEABLE;
-    return hvmemul_do_mmio(
-        dgpa, reps, bytes_per_rep, sgpa, IOREQ_WRITE,
-        !!(ctxt->regs->eflags & X86_EFLAGS_DF), NULL);
+
+    hvm_copy_from_guest_phys(buf, sgpa, *reps * bytes_per_rep);
+    hvm_copy_to_guest_phys(dgpa, buf, *reps * bytes_per_rep);
+
+    xfree(buf);
+
+    return X86EMUL_OKAY;
 }
 
 static int hvmemul_read_segment(

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