[xen-unstable] vmx realmode: When returning to protected mode we have to massage the

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[xen-unstable] vmx realmode: When returning to protected mode we have to massage the

Xen patchbot-unstable
# HG changeset patch
# User Keir Fraser <[hidden email]>
# Date 1196115621 0
# Node ID f9a43c6b5be13ccad25e80cdcc76c4351f2b7625
# Parent  4d6f92fa1014101fff9f01bb3998ca57b139c9b5
vmx realmode: When returning to protected mode we have to massage the
segment state to pass VMENTER's stringent 'sanity checks'.
Signed-off-by: Keir Fraser <[hidden email]>
---
 xen/arch/x86/hvm/vmx/realmode.c |   29 ++++++++++++++++++++++-------
 1 files changed, 22 insertions(+), 7 deletions(-)

diff -r 4d6f92fa1014 -r f9a43c6b5be1 xen/arch/x86/hvm/vmx/realmode.c
--- a/xen/arch/x86/hvm/vmx/realmode.c Mon Nov 26 17:55:23 2007 +0000
+++ b/xen/arch/x86/hvm/vmx/realmode.c Mon Nov 26 22:20:21 2007 +0000
@@ -524,7 +524,8 @@ void vmx_realmode(struct cpu_user_regs *
         if ( rc == X86EMUL_UNHANDLEABLE )
         {
             gdprintk(XENLOG_DEBUG,
-                     "RM %04x:%08lx: %02x %02x %02x %02x %02x %02x\n",
+                     "Real-mode emulation failed @ %04x:%08lx: "
+                     "%02x %02x %02x %02x %02x %02x\n",
                      rm_ctxt.seg_reg[x86_seg_cs].sel, rm_ctxt.insn_buf_eip,
                      rm_ctxt.insn_buf[0], rm_ctxt.insn_buf[1],
                      rm_ctxt.insn_buf[2], rm_ctxt.insn_buf[3],
@@ -534,6 +535,26 @@ void vmx_realmode(struct cpu_user_regs *
         }
     }
 
+    /*
+     * Cannot enter protected mode with bogus selector RPLs and DPLs. Hence we
+     * fix up as best we can, even though this deviates from native execution
+     */
+    if  ( curr->arch.hvm_vcpu.guest_cr[0] & X86_CR0_PE )
+    {
+        /* CS.RPL == SS.RPL == SS.DPL == 0. */
+        rm_ctxt.seg_reg[x86_seg_cs].sel &= ~3;
+        rm_ctxt.seg_reg[x86_seg_ss].sel &= ~3;
+        /* DS,ES,FS,GS: The most uninvasive trick is to set DPL == RPL. */
+        rm_ctxt.seg_reg[x86_seg_ds].attr.fields.dpl =
+            rm_ctxt.seg_reg[x86_seg_ds].sel & 3;
+        rm_ctxt.seg_reg[x86_seg_es].attr.fields.dpl =
+            rm_ctxt.seg_reg[x86_seg_es].sel & 3;
+        rm_ctxt.seg_reg[x86_seg_fs].attr.fields.dpl =
+            rm_ctxt.seg_reg[x86_seg_fs].sel & 3;
+        rm_ctxt.seg_reg[x86_seg_gs].attr.fields.dpl =
+            rm_ctxt.seg_reg[x86_seg_gs].sel & 3;
+    }
+
     for ( i = 0; i < 10; i++ )
         hvm_set_segment_register(curr, i, &rm_ctxt.seg_reg[i]);
 }
@@ -546,12 +567,6 @@ int vmx_realmode_io_complete(void)
     if ( !curr->arch.hvm_vmx.real_mode_io_in_progress )
         return 0;
 
-#if 0
-    gdprintk(XENLOG_DEBUG, "RM I/O %d %c bytes=%d addr=%lx data=%lx\n",
-             p->type, p->dir ? 'R' : 'W',
-             (int)p->size, (long)p->addr, (long)p->data);
-#endif
-
     curr->arch.hvm_vmx.real_mode_io_in_progress = 0;
     if ( p->dir == IOREQ_READ )
     {

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