diff options
| author | Nadav Amit <namit@cs.technion.ac.il> | 2015-01-26 09:32:27 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-01-26 12:17:34 +0100 |
| commit | 82268083fa78452c1c8be30a82984e470d9678c7 (patch) | |
| tree | 94b353219e729453843c1199c68de06eb9703d78 /arch/x86/kvm | |
| parent | bac155310be35e0fa64b066d47625d2a12a75122 (diff) | |
KVM: x86: Emulation of call may use incorrect stack size
On long-mode, when far call that changes cs.l takes place, the stack size is
determined by the new mode. For instance, if we go from 32-bit mode to 64-bit
mode, the stack-size if 64. KVM uses the old stack size.
Fix it.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
| -rw-r--r-- | arch/x86/kvm/emulate.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c index c3b07574942f..81dcf7964701 100644 --- a/arch/x86/kvm/emulate.c +++ b/arch/x86/kvm/emulate.c @@ -741,19 +741,26 @@ static int assign_eip_far(struct x86_emulate_ctxt *ctxt, ulong dst, const struct desc_struct *cs_desc) { enum x86emul_mode mode = ctxt->mode; + int rc; #ifdef CONFIG_X86_64 - if (ctxt->mode >= X86EMUL_MODE_PROT32 && cs_desc->l) { - u64 efer = 0; + if (ctxt->mode >= X86EMUL_MODE_PROT16) { + if (cs_desc->l) { + u64 efer = 0; - ctxt->ops->get_msr(ctxt, MSR_EFER, &efer); - if (efer & EFER_LMA) - mode = X86EMUL_MODE_PROT64; + ctxt->ops->get_msr(ctxt, MSR_EFER, &efer); + if (efer & EFER_LMA) + mode = X86EMUL_MODE_PROT64; + } else + mode = X86EMUL_MODE_PROT32; /* temporary value */ } #endif if (mode == X86EMUL_MODE_PROT16 || mode == X86EMUL_MODE_PROT32) mode = cs_desc->d ? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16; - return assign_eip(ctxt, dst, mode); + rc = assign_eip(ctxt, dst, mode); + if (rc == X86EMUL_CONTINUE) + ctxt->mode = mode; + return rc; } static inline int jmp_rel(struct x86_emulate_ctxt *ctxt, int rel) @@ -3062,6 +3069,7 @@ static int em_call_far(struct x86_emulate_ctxt *ctxt) struct desc_struct old_desc, new_desc; const struct x86_emulate_ops *ops = ctxt->ops; int cpl = ctxt->ops->cpl(ctxt); + enum x86emul_mode prev_mode = ctxt->mode; old_eip = ctxt->_eip; ops->get_segment(ctxt, &old_cs, &old_desc, NULL, VCPU_SREG_CS); @@ -3085,11 +3093,14 @@ static int em_call_far(struct x86_emulate_ctxt *ctxt) rc = em_push(ctxt); /* If we failed, we tainted the memory, but the very least we should restore cs */ - if (rc != X86EMUL_CONTINUE) + if (rc != X86EMUL_CONTINUE) { + pr_warn_once("faulting far call emulation tainted memory\n"); goto fail; + } return rc; fail: ops->set_segment(ctxt, old_cs, &old_desc, 0, VCPU_SREG_CS); + ctxt->mode = prev_mode; return rc; } |