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Commit a6e3407b authored by Avi Kivity's avatar Avi Kivity
Browse files

KVM: Fix SS default ESP/EBP based addressing 



We correctly default to SS when BP is used as a base in 16-bit address mode,
but we don't do that for 32-bit mode.

Fix by adjusting the default to SS when either ESP or EBP is used as the base
register.

Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent cbd27ee7

arch/x86/kvm/emulate.c

+14 −3
Original line number Diff line number Diff line
@@ -974,6 +974,12 @@ static void decode_register_operand(struct x86_emulate_ctxt *ctxt, 
	op->orig_val = op->val;

}



static void adjust_modrm_seg(struct x86_emulate_ctxt *ctxt, int base_reg)

{

	if (base_reg == VCPU_REGS_RSP || base_reg == VCPU_REGS_RBP)

		ctxt->modrm_seg = VCPU_SREG_SS;

}



static int decode_modrm(struct x86_emulate_ctxt *ctxt,

			struct operand *op)

{
@@ -1077,15 +1083,20 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt, 


			if ((base_reg & 7) == 5 && ctxt->modrm_mod == 0)

				modrm_ea += insn_fetch(s32, ctxt);

			else

			else {

				modrm_ea += ctxt->regs[base_reg];

				adjust_modrm_seg(ctxt, base_reg);

			}

			if (index_reg != 4)

				modrm_ea += ctxt->regs[index_reg] << scale;

		} else if ((ctxt->modrm_rm & 7) == 5 && ctxt->modrm_mod == 0) {

			if (ctxt->mode == X86EMUL_MODE_PROT64)

				ctxt->rip_relative = 1;

		} else

			modrm_ea += ctxt->regs[ctxt->modrm_rm];

		} else {

			base_reg = ctxt->modrm_rm;

			modrm_ea += ctxt->regs[base_reg];

			adjust_modrm_seg(ctxt, base_reg);

		}

		switch (ctxt->modrm_mod) {

		case 0:

			if (ctxt->modrm_rm == 5)