Re: [PATCH 1/2] KVM: arm64: Don't write junk to sysregs on reset

[Zenghui Yu <yuzenghui@huawei.com>]

Hi Marc,

On 2019/8/5 20:15, Marc Zyngier wrote:
> At the moment, the way we reset system registers is mildly insane:
> We write junk to them, call the reset functions, and then check that
> we have something else in them.
> 
> The "fun" thing is that this can happen while the guest is running
> (PSCI, for example). If anything in KVM has to evaluate the state
> of a system register while junk is in there, bad thing may happen.
> 
> Let's stop doing that. Instead, we track that we have called a
> reset function for that register, and assume that the reset
> function has done something. This requires fixing a couple of
> sysreg refinition in the trap table.
> 
> In the end, the very need of this reset check is pretty dubious,
> as it doesn't check everything (a lot of the sysregs leave outside of
> the sys_regs[] array). It may well be axed in the near future.
> 
> Signed-off-by: Marc Zyngier <maz@kernel.org>

(Regardless of whether this check is needed or not,) I tested this patch
with kvm-unit-tests:

for i in {1..100}; do QEMU=/path/to/qemu-system-aarch64 accel=kvm 
arch=arm64 ./run_tests.sh; done

And all the tests passed!


Thanks,
zenghui

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