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authorNadav Amit <namit@cs.technion.ac.il>2014-12-25 03:52:19 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2015-01-09 00:48:05 +0300
commit3dc4bc4f6b9265bd05dda007b07eac5a17da0562 (patch)
treeeb6f44fe50a2126a669c3dd62214ad5b178b6b4b /arch/x86/kvm/emulate.c
parent16bebefe29d8495c89961a9d57ea1947547a5211 (diff)
downloadlinux-3dc4bc4f6b9265bd05dda007b07eac5a17da0562.tar.xz
KVM: x86: JMP/CALL using call- or task-gate causes exception
The KVM emulator does not emulate JMP and CALL that target a call gate or a task gate. This patch does not try to implement these scenario as they are presumably rare; yet it returns X86EMUL_UNHANDLEABLE error in such cases instead of generating an exception. Signed-off-by: Nadav Amit <namit@cs.technion.ac.il> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm/emulate.c')
-rw-r--r--arch/x86/kvm/emulate.c54
1 files changed, 34 insertions, 20 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index fff11885a3a0..1fec3ed86cbf 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -263,6 +263,13 @@ struct instr_dual {
#define EFLG_RESERVED_ZEROS_MASK 0xffc0802a
#define EFLG_RESERVED_ONE_MASK 2
+enum x86_transfer_type {
+ X86_TRANSFER_NONE,
+ X86_TRANSFER_CALL_JMP,
+ X86_TRANSFER_RET,
+ X86_TRANSFER_TASK_SWITCH,
+};
+
static ulong reg_read(struct x86_emulate_ctxt *ctxt, unsigned nr)
{
if (!(ctxt->regs_valid & (1 << nr))) {
@@ -1472,7 +1479,7 @@ static int write_segment_descriptor(struct x86_emulate_ctxt *ctxt,
/* Does not support long mode */
static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
u16 selector, int seg, u8 cpl,
- bool in_task_switch,
+ enum x86_transfer_type transfer,
struct desc_struct *desc)
{
struct desc_struct seg_desc, old_desc;
@@ -1526,11 +1533,15 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
return ret;
err_code = selector & 0xfffc;
- err_vec = in_task_switch ? TS_VECTOR : GP_VECTOR;
+ err_vec = (transfer == X86_TRANSFER_TASK_SWITCH) ? TS_VECTOR :
+ GP_VECTOR;
/* can't load system descriptor into segment selector */
- if (seg <= VCPU_SREG_GS && !seg_desc.s)
+ if (seg <= VCPU_SREG_GS && !seg_desc.s) {
+ if (transfer == X86_TRANSFER_CALL_JMP)
+ return X86EMUL_UNHANDLEABLE;
goto exception;
+ }
if (!seg_desc.p) {
err_vec = (seg == VCPU_SREG_SS) ? SS_VECTOR : NP_VECTOR;
@@ -1628,7 +1639,8 @@ static int load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
u16 selector, int seg)
{
u8 cpl = ctxt->ops->cpl(ctxt);
- return __load_segment_descriptor(ctxt, selector, seg, cpl, false, NULL);
+ return __load_segment_descriptor(ctxt, selector, seg, cpl,
+ X86_TRANSFER_NONE, NULL);
}
static void write_register_operand(struct operand *op)
@@ -2040,7 +2052,8 @@ static int em_jmp_far(struct x86_emulate_ctxt *ctxt)
memcpy(&sel, ctxt->src.valptr + ctxt->op_bytes, 2);
- rc = __load_segment_descriptor(ctxt, sel, VCPU_SREG_CS, cpl, false,
+ rc = __load_segment_descriptor(ctxt, sel, VCPU_SREG_CS, cpl,
+ X86_TRANSFER_CALL_JMP,
&new_desc);
if (rc != X86EMUL_CONTINUE)
return rc;
@@ -2129,7 +2142,8 @@ static int em_ret_far(struct x86_emulate_ctxt *ctxt)
/* Outer-privilege level return is not implemented */
if (ctxt->mode >= X86EMUL_MODE_PROT16 && (cs & 3) > cpl)
return X86EMUL_UNHANDLEABLE;
- rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl, false,
+ rc = __load_segment_descriptor(ctxt, (u16)cs, VCPU_SREG_CS, cpl,
+ X86_TRANSFER_RET,
&new_desc);
if (rc != X86EMUL_CONTINUE)
return rc;
@@ -2566,23 +2580,23 @@ static int load_state_from_tss16(struct x86_emulate_ctxt *ctxt,
* it is handled in a context of new task
*/
ret = __load_segment_descriptor(ctxt, tss->ldt, VCPU_SREG_LDTR, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
@@ -2704,31 +2718,31 @@ static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt,
* it is handled in a context of new task
*/
ret = __load_segment_descriptor(ctxt, tss->ldt_selector, VCPU_SREG_LDTR,
- cpl, true, NULL);
+ cpl, X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->es, VCPU_SREG_ES, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->cs, VCPU_SREG_CS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->ss, VCPU_SREG_SS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->ds, VCPU_SREG_DS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->fs, VCPU_SREG_FS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
ret = __load_segment_descriptor(ctxt, tss->gs, VCPU_SREG_GS, cpl,
- true, NULL);
+ X86_TRANSFER_TASK_SWITCH, NULL);
if (ret != X86EMUL_CONTINUE)
return ret;
@@ -3010,8 +3024,8 @@ static int em_call_far(struct x86_emulate_ctxt *ctxt)
ops->get_segment(ctxt, &old_cs, &old_desc, NULL, VCPU_SREG_CS);
memcpy(&sel, ctxt->src.valptr + ctxt->op_bytes, 2);
- rc = __load_segment_descriptor(ctxt, sel, VCPU_SREG_CS, cpl, false,
- &new_desc);
+ rc = __load_segment_descriptor(ctxt, sel, VCPU_SREG_CS, cpl,
+ X86_TRANSFER_CALL_JMP, &new_desc);
if (rc != X86EMUL_CONTINUE)
return X86EMUL_CONTINUE;