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>
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f850e2e603
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d4c6a1549c
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@ -343,11 +343,18 @@ static u32 group2_table[] = {
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};
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/* EFLAGS bit definitions. */
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#define EFLG_ID (1<<21)
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#define EFLG_VIP (1<<20)
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#define EFLG_VIF (1<<19)
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#define EFLG_AC (1<<18)
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#define EFLG_VM (1<<17)
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#define EFLG_RF (1<<16)
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#define EFLG_IOPL (3<<12)
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#define EFLG_NT (1<<14)
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#define EFLG_OF (1<<11)
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#define EFLG_DF (1<<10)
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#define EFLG_IF (1<<9)
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#define EFLG_TF (1<<8)
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#define EFLG_SF (1<<7)
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#define EFLG_ZF (1<<6)
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#define EFLG_AF (1<<4)
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@ -1214,6 +1221,49 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
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return rc;
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}
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static int emulate_popf(struct x86_emulate_ctxt *ctxt,
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struct x86_emulate_ops *ops,
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void *dest, int len)
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{
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int rc;
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unsigned long val, change_mask;
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int iopl = (ctxt->eflags & X86_EFLAGS_IOPL) >> IOPL_SHIFT;
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int cpl = kvm_x86_ops->get_cpl(ctxt->vcpu);
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rc = emulate_pop(ctxt, ops, &val, len);
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if (rc != X86EMUL_CONTINUE)
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return rc;
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change_mask = EFLG_CF | EFLG_PF | EFLG_AF | EFLG_ZF | EFLG_SF | EFLG_OF
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| EFLG_TF | EFLG_DF | EFLG_NT | EFLG_RF | EFLG_AC | EFLG_ID;
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switch(ctxt->mode) {
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case X86EMUL_MODE_PROT64:
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case X86EMUL_MODE_PROT32:
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case X86EMUL_MODE_PROT16:
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if (cpl == 0)
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change_mask |= EFLG_IOPL;
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if (cpl <= iopl)
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change_mask |= EFLG_IF;
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break;
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case X86EMUL_MODE_VM86:
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if (iopl < 3) {
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kvm_inject_gp(ctxt->vcpu, 0);
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return X86EMUL_PROPAGATE_FAULT;
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}
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change_mask |= EFLG_IF;
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break;
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default: /* real mode */
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change_mask |= (EFLG_IOPL | EFLG_IF);
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break;
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}
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*(unsigned long *)dest =
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(ctxt->eflags & ~change_mask) | (val & change_mask);
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return rc;
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}
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static void emulate_push_sreg(struct x86_emulate_ctxt *ctxt, int seg)
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{
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struct decode_cache *c = &ctxt->decode;
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@ -2099,7 +2149,10 @@ special_insn:
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c->dst.type = OP_REG;
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c->dst.ptr = (unsigned long *) &ctxt->eflags;
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c->dst.bytes = c->op_bytes;
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goto pop_instruction;
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rc = emulate_popf(ctxt, ops, &c->dst.val, c->op_bytes);
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if (rc != X86EMUL_CONTINUE)
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goto done;
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break;
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case 0xa0 ... 0xa1: /* mov */
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c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
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c->dst.val = c->src.val;
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