From: Xiaoyao Li <xiaoyao.li@linux.intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>, Tao Xu <tao3.xu@intel.com>
Cc: Radim Krcmar <rkrcmar@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>, kvm <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KVM: vmx: Fix the broken usage of vmx_xsaves_supported
Date: Thu, 20 Jun 2019 16:55:05 +0800 [thread overview]
Message-ID: <2032f811-b583-eca1-3ece-d1e95738ff64@linux.intel.com> (raw)
In-Reply-To: <b3f76acd-cc7e-9cd7-d7f7-404ba756ab87@redhat.com>
On 6/20/2019 4:17 PM, Paolo Bonzini wrote:
> On 20/06/19 08:46, Xiaoyao Li wrote:
>>>
>>> It depends on whether or not processors support the 1-setting instead
>>> of “enable XSAVES/XRSTORS” is 1 in VM-exection control field. Anyway,
>>
>> Yes, whether this field exist or not depends on whether processors
>> support the 1-setting.
>>
>> But if "enable XSAVES/XRSTORS" is clear to 0, XSS_EXIT_BITMAP doesn't
>> work. I think in this case, there is no need to set this vmcs field?
>
> vmx->secondary_exec_control can change; you are making the code more
> complex by relying on the value of the field at the point of vmx_vcpu_setup.
>
At this point. Agreed. It's harmless to set a default value.
> I do _think_ your version is incorrect, because at this point CPUID has
> not been initialized yet and therefore
> vmx_compute_secondary_exec_control has not set SECONDARY_EXEC_XSAVES.
SECONDARY_EXEC_XSAVES is in the opt when setup_vmcs_config, and
vmx_compute_secondary_exec_control() is to clear SECONDARY_EXEC_XSAVES
based on guest cpuid.
> However I may be wrong because I didn't review the code very closely:
> the old code is obvious and so there is no point in changing it.
you mean this part about XSS_EXIT_BITMAP? how about the other part in
vmx_set/get_msr() in this patch?
> Paolo
>
next prev parent reply other threads:[~2019-06-20 8:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-20 5:03 [PATCH] KVM: vmx: Fix the broken usage of vmx_xsaves_supported Tao Xu
2019-06-20 6:40 ` Wanpeng Li
2019-06-20 6:46 ` Xiaoyao Li
2019-06-20 8:17 ` Paolo Bonzini
2019-06-20 8:27 ` Wanpeng Li
2019-06-20 8:36 ` Paolo Bonzini
2019-06-20 8:55 ` Xiaoyao Li [this message]
2019-06-20 8:59 ` Paolo Bonzini
2019-06-20 9:02 ` Wanpeng Li
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