From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Huaitong Han <huaitong.han@intel.com>,
gleb@kernel.org
Cc: kvm@vger.kernel.org
Subject: Re: [PATCH V4 7/7] KVM, pkeys: disable PKU feature without ept
Date: Wed, 9 Mar 2016 13:51:32 +0800 [thread overview]
Message-ID: <56DFB9E4.1050609@linux.intel.com> (raw)
In-Reply-To: <56DEA33B.1010005@redhat.com>
On 03/08/2016 06:02 PM, Paolo Bonzini wrote:
>
>
> On 08/03/2016 10:32, Xiao Guangrong wrote:
>> On 03/08/2016 04:47 PM, Paolo Bonzini wrote:
>>> Some XSAVE features (currently only MPX, but in the future PKRU too)
>>> will force eagerfpu on, see fpu__init_system_ctx_switch:
>>>
>>> if (xfeatures_mask & XFEATURE_MASK_EAGER) {
>>> if (eagerfpu == DISABLE) {
>>> xfeatures_mask &= ~XFEATURE_MASK_EAGER;
>>
>> So if the kernel parameter, eagerfpu is set to "off", then eager is not
>> enabled, so PKRU can not work in KVM?
>
> Yes. Neither PKRU nor MPX.
Er... I noticed fpregs is not switched if the CPU is running in KVM module
(vcpu is not scheduled out and does not exit to userspace), that is why
read_pkru() can be used to read guest's PKRU in the patch 4.
However, then guest can fully control the access of userspace's memory if
CR4.PKRU is enabled on host and KVM needs to access QEMU's memory to do some
emulation anyway. Is it really safe？
next prev parent reply other threads:[~2016-03-09 5:51 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-05 11:27 [PATCH V4 0/7] KVM, pkeys: add memory protection-key support Huaitong Han
2016-03-05 11:27 ` [PATCH V4 1/7] KVM, pkeys: expose CPUID/CR4 to guest Huaitong Han
2016-03-06 7:15 ` Xiao Guangrong
2016-03-06 23:20 ` Paolo Bonzini
2016-03-08 7:39 ` Xiao Guangrong
2016-03-08 7:58 ` Paolo Bonzini
2016-03-05 11:27 ` [PATCH V4 2/7] KVM, pkeys: disable pkeys for guests in non-paging mode Huaitong Han
2016-03-06 7:19 ` Xiao Guangrong
2016-03-08 12:09 ` Yang Zhang
2016-03-08 12:11 ` Paolo Bonzini
2016-03-08 13:02 ` Yang Zhang
2016-03-05 11:27 ` [PATCH V4 3/7] KVM, pkeys: update memeory permission bitmask for pkeys Huaitong Han
2016-03-06 7:42 ` Xiao Guangrong
2016-03-06 23:14 ` Paolo Bonzini
2016-03-08 7:35 ` Xiao Guangrong
2016-03-08 8:29 ` Paolo Bonzini
2016-03-08 9:19 ` Xiao Guangrong
2016-03-08 10:01 ` Paolo Bonzini
2016-03-09 5:03 ` Xiao Guangrong
2016-03-09 8:10 ` Paolo Bonzini
2016-03-05 11:27 ` [PATCH V4 4/7] KVM, pkeys: add pkeys support for permission_fault logic Huaitong Han
2016-03-06 8:00 ` Xiao Guangrong
2016-03-06 20:36 ` Paolo Bonzini
2016-03-06 23:29 ` Paolo Bonzini
2016-03-08 5:57 ` Xiao Guangrong
2016-03-05 11:27 ` [PATCH V4 5/7] KVM, pkeys: Add pkeys support for gva_to_gpa funcions Huaitong Han
2016-03-06 8:01 ` Xiao Guangrong
2016-03-06 21:33 ` Paolo Bonzini
2016-03-05 11:27 ` [PATCH V4 6/7] KVM, pkeys: add pkeys support for xsave state Huaitong Han
2016-03-06 8:27 ` Xiao Guangrong
2016-03-05 11:27 ` [PATCH V4 7/7] KVM, pkeys: disable PKU feature without ept Huaitong Han
2016-03-06 9:28 ` Xiao Guangrong
2016-03-06 20:32 ` Paolo Bonzini
2016-03-08 5:54 ` Xiao Guangrong
2016-03-08 8:47 ` Paolo Bonzini
2016-03-08 9:32 ` Xiao Guangrong
2016-03-08 10:02 ` Paolo Bonzini
2016-03-09 5:51 ` Xiao Guangrong [this message]
2016-03-09 6:37 ` Yang Zhang
2016-03-09 7:21 ` Xiao Guangrong
2016-03-09 7:41 ` Yang Zhang
2016-03-09 7:50 ` Xiao Guangrong
2016-03-09 8:00 ` Yang Zhang
2016-03-09 8:05 ` Xiao Guangrong
2016-03-09 8:18 ` Paolo Bonzini
2016-03-09 8:13 ` Paolo Bonzini
2016-03-09 6:24 ` Yang Zhang
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