1.1 --- a/xen/arch/x86/hvm/hvm.c	Wed Feb 13 16:28:38 2008 +0000
     1.2 +++ b/xen/arch/x86/hvm/hvm.c	Wed Feb 13 16:35:51 2008 +0000
     1.3 @@ -1386,6 +1386,7 @@ void hvm_task_switch(
     1.4  static enum hvm_copy_result __hvm_copy(
     1.5      void *buf, paddr_t addr, int size, int dir, int virt, int fetch)
     1.6  {
     1.7 +    struct vcpu *curr = current;
     1.8      unsigned long gfn, mfn;
     1.9      p2m_type_t p2mt;
    1.10      char *p;
    1.11 @@ -1394,12 +1395,22 @@ static enum hvm_copy_result __hvm_copy(
    1.12  
    1.13      if ( virt )
    1.14      {
    1.15 -        struct segment_register sreg;
    1.16 -        hvm_get_segment_register(current, x86_seg_ss, &sreg);
    1.17 -        if ( sreg.attr.fields.dpl == 3 )
    1.18 -            pfec |= PFEC_user_mode;
    1.19 +        /*
    1.20 +         * We cannot use hvm_get_segment_register() while executing in
    1.21 +         * vmx_realmode() as segment register state is cached. Furthermore,
    1.22 +         * VMREADs on every data access hurts emulation performance.
    1.23 +         */
    1.24 +        if ( !curr->arch.hvm_vmx.vmxemul )
    1.25 +        {
    1.26 +            struct segment_register sreg;
    1.27 +            hvm_get_segment_register(curr, x86_seg_ss, &sreg);
    1.28 +            if ( sreg.attr.fields.dpl == 3 )
    1.29 +                pfec |= PFEC_user_mode;
    1.30 +        }
    1.31 +
    1.32          if ( dir ) 
    1.33              pfec |= PFEC_write_access;
    1.34 +
    1.35          if ( fetch ) 
    1.36              pfec |= PFEC_insn_fetch;
    1.37      }
    1.38 @@ -1411,7 +1422,7 @@ static enum hvm_copy_result __hvm_copy(
    1.39  
    1.40          if ( virt )
    1.41          {
    1.42 -            gfn = paging_gva_to_gfn(current, addr, &pfec);
    1.43 +            gfn = paging_gva_to_gfn(curr, addr, &pfec);
    1.44              if ( gfn == INVALID_GFN )
    1.45              {
    1.46                  if ( virt == 2 ) /* 2 means generate a fault */
    1.47 @@ -1435,7 +1446,7 @@ static enum hvm_copy_result __hvm_copy(
    1.48          if ( dir )
    1.49          {
    1.50              memcpy(p, buf, count); /* dir == TRUE:  *to* guest */
    1.51 -            paging_mark_dirty(current->domain, mfn);
    1.52 +            paging_mark_dirty(curr->domain, mfn);
    1.53          }
    1.54          else
    1.55              memcpy(buf, p, count); /* dir == FALSE: *from guest */