From: Marc Zyngier <marc.zyngier@arm.com>
To: gengdongjiu <gengdongjiu@huawei.com>, James Morse <james.morse@arm.com>
Cc: christoffer.dall@linaro.org, vladimir.murzin@arm.com,
rkrcmar@redhat.com, catalin.marinas@arm.com,
shankerd@codeaurora.org, linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, zhanghaibin7@huawei.com,
huangshaoyu@huawei.com
Subject: Re: [PATCH] arm64: KVM: VHE: reset PSTATE.UAO when switch to host
Date: Thu, 7 Sep 2017 11:13:46 +0100 [thread overview]
Message-ID: <ec27c833-c9f7-d144-3c6f-a87a3bf3d97f@arm.com> (raw)
In-Reply-To: <f710f68a-1e89-85a6-41a6-afc7588114db@huawei.com>
On 07/09/17 11:05, gengdongjiu wrote:
> Hi James,
>
> On 2017/9/7 17:20, James Morse wrote:
>> Hi Dongjiu Geng,
>>
>> On 07/09/17 06:54, Dongjiu Geng wrote:
>>> In VHE mode, host kernel runs in the EL2 and can enable
>>> 'User Access Override' when fs==KERNEL_DS so that it can
>>> access kernel memory. However, PSTATE.UAO is set to 0 on
>>> an exception taken from EL1 to EL2. Thus when VHE is used
>>> and exception taken from a guest UAO will be disabled and
>>> host will use the incorrect PSTATE.UAO. So check and reset
>>> the PSTATE.UAO when switching to host.
>>
>> This would only be a problem if KVM were calling into world-switch with
>> fs==KERNEL_DS. I can't see where this happens.
> Not only KVM, may also kernel sets the fs == KERNEL_DS before calling into world-switch
How? Please describe the exact sequence of event that lead to this
situation with the current code base.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2017-09-07 10:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-07 5:54 [PATCH] arm64: KVM: VHE: reset PSTATE.UAO when switch to host Dongjiu Geng
2017-09-07 9:20 ` James Morse
2017-09-07 10:05 ` gengdongjiu
2017-09-07 10:13 ` Marc Zyngier [this message]
2017-09-07 11:49 ` gengdongjiu
2017-09-07 12:00 ` Marc Zyngier
-- strict thread matches above, loose matches on Subject: below --
2017-09-07 15:03 gengdongjiu
2017-09-07 15:23 ` Marc Zyngier
2017-09-08 7:19 ` gengdongjiu
2017-09-08 8:21 ` Marc Zyngier
2017-09-08 9:05 ` gengdongjiu
2017-09-08 12:10 ` Marc Zyngier
2017-09-08 13:33 gengdongjiu
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