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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: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
hifive-unleashed-5.1
Marc Zyngier 2017-03-27 17:03:43 +01:00 committed by Christoffer Dall
parent e70b952263
commit b6b7a8069d
1 changed files with 16 additions and 11 deletions
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27
arch/arm64/kvm/sys_regs.c
View File

@ -1678,20 +1678,25 @@ static int kvm_handle_cp_64(struct kvm_vcpu *vcpu,
params.regval |= vcpu_get_reg(vcpu, Rt2) << 32;
}
if (!emulate_cp(vcpu, &params, target_specific, nr_specific))
goto out;
if (!emulate_cp(vcpu, &params, global, nr_global))
goto out;
/*
* Try to emulate the coprocessor access using the target
* specific table first, and using the global table afterwards.
* If either of the tables contains a handler, handle the
* potential register operation in the case of a read and return
* with success.
*/
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 */
if (!params.is_write) {
vcpu_set_reg(vcpu, Rt, lower_32_bits(params.regval));
vcpu_set_reg(vcpu, Rt2, upper_32_bits(params.regval));
}
unhandled_cp_access(vcpu, &params);
out:
/* Split up the value between registers for the read side */
if (!params.is_write) {
vcpu_set_reg(vcpu, Rt, lower_32_bits(params.regval));
vcpu_set_reg(vcpu, Rt2, upper_32_bits(params.regval));
return 1;
}
unhandled_cp_access(vcpu, &params);
return 1;
}