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KVM: x86 emulator: Fix popf emulation 

POPF behaves differently depending on current CPU mode. Emulate correct
logic to prevent guest from changing flags that it can't change otherwise.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Gleb Natapov 2010-02-10 14:21:34 +02:00 committed by Marcelo Tosatti
parent f850e2e603
commit d4c6a1549c
1 changed files with 54 additions and 1 deletions
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55
arch/x86/kvm/emulate.c
View File

@ -343,11 +343,18 @@ static u32 group2_table[] = {
};
/* EFLAGS bit definitions. */
#define EFLG_ID (1<<21)
#define EFLG_VIP (1<<20)
#define EFLG_VIF (1<<19)
#define EFLG_AC (1<<18)
#define EFLG_VM (1<<17)
#define EFLG_RF (1<<16)
#define EFLG_IOPL (3<<12)
#define EFLG_NT (1<<14)
#define EFLG_OF (1<<11)
#define EFLG_DF (1<<10)
#define EFLG_IF (1<<9)
#define EFLG_TF (1<<8)
#define EFLG_SF (1<<7)
#define EFLG_ZF (1<<6)
#define EFLG_AF (1<<4)
@ -1214,6 +1221,49 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
return rc;
}
static int emulate_popf(struct x86_emulate_ctxt *ctxt,
struct x86_emulate_ops *ops,
void *dest, int len)
{
int rc;
unsigned long val, change_mask;
int iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
int cpl = kvm_x86_ops->get_cpl(ctxt->vcpu);
rc = emulate_pop(ctxt, ops, &val, len);
if (rc != X86EMUL_CONTINUE)
return rc;
change_mask = EFLG_CF | EFLG_PF | EFLG_AF | EFLG_ZF | EFLG_SF | EFLG_OF
| EFLG_TF | EFLG_DF | EFLG_NT | EFLG_RF | EFLG_AC | EFLG_ID;
switch(ctxt->mode) {
case X86EMUL_MODE_PROT64:
case X86EMUL_MODE_PROT32:
case X86EMUL_MODE_PROT16:
if (cpl == 0)
change_mask |= EFLG_IOPL;
if (cpl <= iopl)
change_mask |= EFLG_IF;
break;
case X86EMUL_MODE_VM86:
if (iopl < 3) {
kvm_inject_gp(ctxt->vcpu, 0);
return X86EMUL_PROPAGATE_FAULT;
}
change_mask |= EFLG_IF;
break;
default: /* real mode */
change_mask |= (EFLG_IOPL | EFLG_IF);
break;
}
*(unsigned long *)dest =
(ctxt->eflags & ~change_mask) | (val & change_mask);
return rc;
}
static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt, int seg)
{
struct decode_cache *c = &ctxt->decode;
@ -2099,7 +2149,10 @@ special_insn:
c->dst.type = OP_REG;
c->dst.ptr = (unsigned long *) &ctxt->eflags;
c->dst.bytes = c->op_bytes;
goto pop_instruction;
rc = emulate_popf(ctxt, ops, &c->dst.val, c->op_bytes);
if (rc != X86EMUL_CONTINUE)
goto done;
break;
case 0xa0 ... 0xa1: /* mov */
c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
c->dst.val = c->src.val;