Commit b6b7a806 authored by Marc Zyngier's avatar Marc Zyngier Committed by Christoffer Dall
Browse files

arm64: KVM: Do not corrupt registers on failed 64bit CP read 



If we fail to emulate a mrrc instruction, we:
1) deliver an exception,
2) spit a nastygram on the console,
3) write back some garbage to Rt/Rt2

While 1) and 2) are perfectly acceptable, 3) is out of the scope of
the architecture... Let's mimick the code in kvm_handle_cp_32 and
be more cautious.

Reviewed-by: default avatarChristoffer Dall <cdall@linaro.org>
Signed-off-by: default avatarMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: default avatarChristoffer Dall <cdall@linaro.org>
parent e70b9522

arch/arm64/kvm/sys_regs.c

+16 −11
Original line number Original line Diff line number Diff line
@@ -1678,14 +1678,15 @@ static int kvm_handle_cp_64(struct kvm_vcpu *vcpu, 
		params.regval |= vcpu_get_reg(vcpu, Rt2) << 32;

		params.regval |= vcpu_get_reg(vcpu, Rt2) << 32;

	}

	}





	if (!emulate_cp(vcpu, &params, target_specific, nr_specific))

	/*

		goto out;

	 * Try to emulate the coprocessor access using the target

	if (!emulate_cp(vcpu, &params, global, nr_global))

	 * specific table first, and using the global table afterwards.

		goto out;

	 * If either of the tables contains a handler, handle the



	 * potential register operation in the case of a read and return

	unhandled_cp_access(vcpu, &params);

	 * with success.



	 */

out:

	if (!emulate_cp(vcpu, &params, target_specific, nr_specific) ||

	    !emulate_cp(vcpu, &params, global, nr_global)) {

		/* Split up the value between registers for the read side */

		/* Split up the value between registers for the read side */

		if (!params.is_write) {

		if (!params.is_write) {

			vcpu_set_reg(vcpu, Rt, lower_32_bits(params.regval));

			vcpu_set_reg(vcpu, Rt, lower_32_bits(params.regval));
@@ -1695,6 +1696,10 @@ out: 
		return 1;

		return 1;

	}

	}





	unhandled_cp_access(vcpu, &params);

	return 1;

}



/**

/**

 * kvm_handle_cp_32 -- handles a mrc/mcr trap on a guest CP14/CP15 access

 * kvm_handle_cp_32 -- handles a mrc/mcr trap on a guest CP14/CP15 access

 * @vcpu: The VCPU pointer

 * @vcpu: The VCPU pointer

CRA Git | Maintained and supported by SUSTech CRA and CCSE