releases/2.6.32.12/kvm-x86-emulator-add-virtual-8086-mode-of-emulation.patch

   1 From stefan.bader@canonical.com  Wed Apr  7 14:41:50 2010
   2 From: Gleb Natapov <gleb@redhat.com>
   3 Date: Fri, 19 Mar 2010 15:47:30 +0100
   4 Subject: KVM: x86 emulator: Add Virtual-8086 mode of emulation
   5 To: stable@kernel.org
   6 Cc: Marcelo Tosatti <mtosatti@redhat.com>, Avi Kivity <avi@redhat.com>, Gleb Natapov <gleb@redhat.com>
   7 Message-ID: <1269010059-25309-3-git-send-email-stefan.bader@canonical.com>
   8
   9
  10 From: Gleb Natapov <gleb@redhat.com>
  11
  12 commit a0044755679f3e761b8b95995e5f2db2b7efd0f6 upstream
  13
  14 For some instructions CPU behaves differently for real-mode and
  15 virtual 8086. Let emulator know which mode cpu is in, so it will
  16 not poke into vcpu state directly.
  17
  18 Signed-off-by: Gleb Natapov <gleb@redhat.com>
  19 Signed-off-by: Avi Kivity <avi@redhat.com>
  20 Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  22 ---
  23  arch/x86/include/asm/kvm_emulate.h |    1 +
  24  arch/x86/kvm/emulate.c             |   14 +++++++-------
  25  arch/x86/kvm/x86.c                 |    3 ++-
  26  3 files changed, 10 insertions(+), 8 deletions(-)
  27
  28 --- a/arch/x86/include/asm/kvm_emulate.h
  29 +++ b/arch/x86/include/asm/kvm_emulate.h
  30 @@ -168,6 +168,7 @@ struct x86_emulate_ctxt {
  31
  32  /* Execution mode, passed to the emulator. */
  33  #define X86EMUL_MODE_REAL     0        /* Real mode.             */
  34 +#define X86EMUL_MODE_VM86     1        /* Virtual 8086 mode.     */
  35  #define X86EMUL_MODE_PROT16   2        /* 16-bit protected mode. */
  36  #define X86EMUL_MODE_PROT32   4        /* 32-bit protected mode. */
  37  #define X86EMUL_MODE_PROT64   8        /* 64-bit (long) mode.    */
  38 --- a/arch/x86/kvm/emulate.c
  39 +++ b/arch/x86/kvm/emulate.c
  40 @@ -895,6 +895,7 @@ x86_decode_insn(struct x86_emulate_ctxt
  41
  42         switch (mode) {
  43         case X86EMUL_MODE_REAL:
  44 +       case X86EMUL_MODE_VM86:
  45         case X86EMUL_MODE_PROT16:
  46                 def_op_bytes = def_ad_bytes = 2;
  47                 break;
  48 @@ -1453,7 +1454,7 @@ emulate_syscall(struct x86_emulate_ctxt
  49
  50         /* syscall is not available in real mode */
  51         if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL
  52 -               || !(ctxt->vcpu->arch.cr0 & X86_CR0_PE))
  53 +           || ctxt->mode == X86EMUL_MODE_VM86)
  54                 return -1;
  55
  56         setup_syscalls_segments(ctxt, &cs, &ss);
  57 @@ -1505,9 +1506,8 @@ emulate_sysenter(struct x86_emulate_ctxt
  58         if (c->lock_prefix)
  59                 return -1;
  60
  61 -       /* inject #GP if in real mode or paging is disabled */
  62 -       if (ctxt->mode == X86EMUL_MODE_REAL ||
  63 -               !(ctxt->vcpu->arch.cr0 & X86_CR0_PE)) {
  64 +       /* inject #GP if in real mode */
  65 +       if (ctxt->mode == X86EMUL_MODE_REAL) {
  66                 kvm_inject_gp(ctxt->vcpu, 0);
  67                 return -1;
  68         }
  69 @@ -1571,9 +1571,9 @@ emulate_sysexit(struct x86_emulate_ctxt
  70         if (c->lock_prefix)
  71                 return -1;
  72
  73 -       /* inject #GP if in real mode or paging is disabled */
  74 -       if (ctxt->mode == X86EMUL_MODE_REAL
  75 -               || !(ctxt->vcpu->arch.cr0 & X86_CR0_PE)) {
  76 +       /* inject #GP if in real mode or Virtual 8086 mode */
  77 +       if (ctxt->mode == X86EMUL_MODE_REAL ||
  78 +           ctxt->mode == X86EMUL_MODE_VM86) {
  79                 kvm_inject_gp(ctxt->vcpu, 0);
  80                 return -1;
  81         }
  82 --- a/arch/x86/kvm/x86.c
  83 +++ b/arch/x86/kvm/x86.c
  84 @@ -2828,8 +2828,9 @@ int emulate_instruction(struct kvm_vcpu
  85                 vcpu->arch.emulate_ctxt.vcpu = vcpu;
  86                 vcpu->arch.emulate_ctxt.eflags = kvm_x86_ops->get_rflags(vcpu);
  87                 vcpu->arch.emulate_ctxt.mode =
  88 +                       (!(vcpu->arch.cr0 & X86_CR0_PE)) ? X86EMUL_MODE_REAL :
  89                         (vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)
  90 -                       ? X86EMUL_MODE_REAL : cs_l
  91 +                       ? X86EMUL_MODE_VM86 : cs_l
  92                         ? X86EMUL_MODE_PROT64 : cs_db
  93                         ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
  94