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KVM: x86 emulator: Add sysenter emulation 

Handle #UD intercept of the sysenter instruction in 32bit compat mode on
an AMD host.
Setup the segment descriptors for CS and SS and the EIP/ESP registers
according to the manual.

Signed-off-by: Christoph Egger <christoph.egger@amd.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Andre Przywara 2009-06-18 12:56:01 +02:00 committed by Avi Kivity
parent e66bb2ccdc
commit 8c60435261
1 changed files with 69 additions and 1 deletions
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70
arch/x86/kvm/x86_emulate.c
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@ -1476,6 +1476,71 @@ emulate_syscall(struct x86_emulate_ctxt *ctxt)
return 0;
}
static int
emulate_sysenter(struct x86_emulate_ctxt *ctxt)
{
struct decode_cache *c = &ctxt->decode;
struct kvm_segment cs, ss;
u64 msr_data;
/* inject #UD if LOCK prefix is used */
if (c->lock_prefix)
return -1;
/* inject #GP if in real mode or paging is disabled */
if (ctxt->mode == X86EMUL_MODE_REAL ||
!(ctxt->vcpu->arch.cr0 & X86_CR0_PE)) {
kvm_inject_gp(ctxt->vcpu, 0);
return -1;
}
/* XXX sysenter/sysexit have not been tested in 64bit mode.
* Therefore, we inject an #UD.
*/
if (ctxt->mode == X86EMUL_MODE_PROT64)
return -1;
setup_syscalls_segments(ctxt, &cs, &ss);
kvm_x86_ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_CS, &msr_data);
switch (ctxt->mode) {
case X86EMUL_MODE_PROT32:
if ((msr_data & 0xfffc) == 0x0) {
kvm_inject_gp(ctxt->vcpu, 0);
return -1;
}
break;
case X86EMUL_MODE_PROT64:
if (msr_data == 0x0) {
kvm_inject_gp(ctxt->vcpu, 0);
return -1;
}
break;
}
ctxt->eflags &= ~(EFLG_VM | EFLG_IF | EFLG_RF);
cs.selector = (u16)msr_data;
cs.selector &= ~SELECTOR_RPL_MASK;
ss.selector = cs.selector + 8;
ss.selector &= ~SELECTOR_RPL_MASK;
if (ctxt->mode == X86EMUL_MODE_PROT64
|| is_long_mode(ctxt->vcpu)) {
cs.db = 0;
cs.l = 1;
}
kvm_x86_ops->set_segment(ctxt->vcpu, &cs, VCPU_SREG_CS);
kvm_x86_ops->set_segment(ctxt->vcpu, &ss, VCPU_SREG_SS);
kvm_x86_ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_EIP, &msr_data);
c->eip = msr_data;
kvm_x86_ops->get_msr(ctxt->vcpu, MSR_IA32_SYSENTER_ESP, &msr_data);
c->regs[VCPU_REGS_RSP] = msr_data;
return 0;
}
int
x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
{
@ -2144,7 +2209,10 @@ twobyte_insn:
c->dst.type = OP_NONE;
break;
case 0x34: /* sysenter */
goto cannot_emulate;
if (emulate_sysenter(ctxt) == -1)
goto cannot_emulate;
else
goto writeback;
break;
case 0x35: /* sysexit */
goto cannot_emulate;