linux-kernel - Re: [RFC PATCH 1/2] KVM: x86: Add a new system attribute for dynamic XSTATE component

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Message-ID: <e52f26d4-c52a-e20d-7bc0-663bb4979827@intel.com>
Date:   Thu, 25 Aug 2022 13:45:22 -0700
From:   "Chang S. Bae" <chang.seok.bae@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
CC:     <kvm@...r.kernel.org>, <pbonzini@...hat.com>,
        <linux-kernel@...r.kernel.org>, <yang.zhong@...el.com>
Subject: Re: [RFC PATCH 1/2] KVM: x86: Add a new system attribute for dynamic
 XSTATE component

On 8/25/2022 9:19 AM, Sean Christopherson wrote:
> 
> Adding new uAPI and new exports to eliminate one line of userspace code is not a
> good tradeoff.  Am I missing something?  This really seems like solution looking
> for a problem.

Well, then that's your call.

Yeah, that simplification is really minor. With this, I would rather 
think KVM wants enforcement before relaying the request to the host. 
That enforcement is unthinkable without supported_xcr0. But it looks 
like userspace is somehow trusted here for KVM.

Thanks,
Chang