debuggers.hg

changeset 17077:4c64376d439d

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x86 vmx: Streamline vmx_interrupt_blocked() to avoid a VMREAD if
interrupt delivery is blocked by EFLAGS.IF. This speeds up real-mode
emulation in some cases (where we are currently executing
hvm_local_events_need_delivery() after every instruction).
Signed-off-by: Keir Fraser <keir.fraser@citrix.com>
author Keir Fraser <keir.fraser@citrix.com>
date Wed Feb 13 16:28:38 2008 +0000 (2008-02-13)
parents e56c9fe4a7e6
children ec1fa84147ad
files xen/arch/x86/hvm/vmx/vmx.c
line diff
     1.1 --- a/xen/arch/x86/hvm/vmx/vmx.c	Wed Feb 13 16:25:32 2008 +0000
     1.2 +++ b/xen/arch/x86/hvm/vmx/vmx.c	Wed Feb 13 16:28:38 2008 +0000
     1.3 @@ -917,6 +917,14 @@ static enum hvm_intblk vmx_interrupt_blo
     1.4  {
     1.5      unsigned long intr_shadow;
     1.6  
     1.7 +    /*
     1.8 +     * Test EFLAGS.IF first. It is often the most likely reason for interrupt
     1.9 +     * blockage, and is the cheapest to test (because no VMREAD is required).
    1.10 +     */
    1.11 +    if ( (intack.source != hvm_intsrc_nmi) &&
    1.12 +         !(guest_cpu_user_regs()->eflags & X86_EFLAGS_IF) )
    1.13 +        return hvm_intblk_rflags_ie;
    1.14 +
    1.15      intr_shadow = __vmread(GUEST_INTERRUPTIBILITY_INFO);
    1.16  
    1.17      if ( intr_shadow & (VMX_INTR_SHADOW_STI|VMX_INTR_SHADOW_MOV_SS) )
    1.18 @@ -929,9 +937,6 @@ static enum hvm_intblk vmx_interrupt_blo
    1.19      ASSERT((intack.source == hvm_intsrc_pic) ||
    1.20             (intack.source == hvm_intsrc_lapic));
    1.21  
    1.22 -    if ( !(guest_cpu_user_regs()->eflags & X86_EFLAGS_IF) )
    1.23 -        return hvm_intblk_rflags_ie;
    1.24 -
    1.25      return hvm_intblk_none;
    1.26  }
    1.27