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Commit 3b88e41a authored by Joerg Roedel's avatar Joerg Roedel Committed by Avi Kivity
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KVM: SVM: Add intercept check for accessing dr registers 



This patch adds the intercept checks for instruction
accessing the debug registers.

Signed-off-by: default avatarJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent cfec82cb

arch/x86/include/asm/kvm_emulate.h

+2 −0
Original line number Diff line number Diff line
@@ -309,6 +309,8 @@ enum x86_intercept { 
	x86_intercept_clts,

	x86_intercept_lmsw,

	x86_intercept_smsw,

	x86_intercept_dr_read,

	x86_intercept_dr_write,

	x86_intercept_lidt,

	x86_intercept_sidt,

	x86_intercept_lgdt,

arch/x86/kvm/emulate.c

+48 −15
Original line number Diff line number Diff line
@@ -509,6 +509,11 @@ static int emulate_exception(struct x86_emulate_ctxt *ctxt, int vec, 
	return X86EMUL_PROPAGATE_FAULT;

}



static int emulate_db(struct x86_emulate_ctxt *ctxt)

{

	return emulate_exception(ctxt, DB_VECTOR, 0, false);

}



static int emulate_gp(struct x86_emulate_ctxt *ctxt, int err)

{

	return emulate_exception(ctxt, GP_VECTOR, err, true);
@@ -2534,6 +2539,47 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt) 
	return X86EMUL_CONTINUE;

}



static int check_dr7_gd(struct x86_emulate_ctxt *ctxt)

{

	unsigned long dr7;



	ctxt->ops->get_dr(7, &dr7, ctxt->vcpu);



	/* Check if DR7.Global_Enable is set */

	return dr7 & (1 << 13);

}



static int check_dr_read(struct x86_emulate_ctxt *ctxt)

{

	struct decode_cache *c = &ctxt->decode;

	int dr = c->modrm_reg;

	u64 cr4;



	if (dr > 7)

		return emulate_ud(ctxt);



	cr4 = ctxt->ops->get_cr(4, ctxt->vcpu);

	if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5))

		return emulate_ud(ctxt);



	if (check_dr7_gd(ctxt))

		return emulate_db(ctxt);



	return X86EMUL_CONTINUE;

}



static int check_dr_write(struct x86_emulate_ctxt *ctxt)

{

	struct decode_cache *c = &ctxt->decode;

	u64 new_val = c->src.val64;

	int dr = c->modrm_reg;



	if ((dr == 6 || dr == 7) && (new_val & 0xffffffff00000000ULL))

		return emulate_gp(ctxt, 0);



	return check_dr_read(ctxt);

}



#define D(_y) { .flags = (_y) }

#define DI(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i }

#define DIP(_y, _i, _p) { .flags = (_y), .intercept = x86_intercept_##_i, \
@@ -2728,9 +2774,9 @@ static struct opcode twobyte_table[256] = { 
	N, N, N, N, N, N, N, N, D(ImplicitOps | ModRM), N, N, N, N, N, N, N,

	/* 0x20 - 0x2F */

	DIP(ModRM | DstMem | Priv | Op3264, cr_read, check_cr_read),

	D(ModRM | DstMem | Priv | Op3264),

	DIP(ModRM | DstMem | Priv | Op3264, dr_read, check_dr_read),

	DIP(ModRM | SrcMem | Priv | Op3264, cr_write, check_cr_write),

	D(ModRM | SrcMem | Priv | Op3264),

	DIP(ModRM | SrcMem | Priv | Op3264, dr_write, check_dr_write),

	N, N, N, N,

	N, N, N, N, N, N, N, N,

	/* 0x30 - 0x3F */
@@ -3818,12 +3864,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		c->dst.val = ops->get_cr(c->modrm_reg, ctxt->vcpu);

		break;

	case 0x21: /* mov from dr to reg */

		if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&

		    (c->modrm_reg == 4 || c->modrm_reg == 5)) {

			emulate_ud(ctxt);

			rc = X86EMUL_PROPAGATE_FAULT;

			goto done;

		}

		ops->get_dr(c->modrm_reg, &c->dst.val, ctxt->vcpu);

		break;

	case 0x22: /* mov reg, cr */
@@ -3835,13 +3875,6 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt) 
		c->dst.type = OP_NONE;

		break;

	case 0x23: /* mov from reg to dr */

		if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&

		    (c->modrm_reg == 4 || c->modrm_reg == 5)) {

			emulate_ud(ctxt);

			rc = X86EMUL_PROPAGATE_FAULT;

			goto done;

		}



		if (ops->set_dr(c->modrm_reg, c->src.val &

				((ctxt->mode == X86EMUL_MODE_PROT64) ?

				 ~0ULL : ~0U), ctxt->vcpu) < 0) {

arch/x86/kvm/svm.c

+6 −0
Original line number Diff line number Diff line
@@ -3882,6 +3882,8 @@ static struct __x86_intercept { 
	[x86_intercept_clts]		= POST_EX(SVM_EXIT_WRITE_CR0),

	[x86_intercept_lmsw]		= POST_EX(SVM_EXIT_WRITE_CR0),

	[x86_intercept_smsw]		= POST_EX(SVM_EXIT_READ_CR0),

	[x86_intercept_dr_read]		= POST_EX(SVM_EXIT_READ_DR0),

	[x86_intercept_dr_write]	= POST_EX(SVM_EXIT_WRITE_DR0),

};



#undef POST_EX
@@ -3939,6 +3941,10 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu, 


		break;

	}

	case SVM_EXIT_READ_DR0:

	case SVM_EXIT_WRITE_DR0:

		icpt_info.exit_code += info->modrm_reg;

		break;

	default:

		break;

	}