From:   Thomas Gleixner <tglx@linutronix.de>
To:     isaku.yamahata@intel.com, Ingo Molnar <mingo@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, erdemaktas@google.com,
        Connor Kuehl <ckuehl@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [RFC PATCH v3 46/59] KVM: VMX: Move register caching logic to
 common code
In-Reply-To: <2f3c1207f66f44fdd2f3eb0809d552f5632e4b41.1637799475.git.isaku.yamahata@intel.com>
References: <cover.1637799475.git.isaku.yamahata@intel.com>
 <2f3c1207f66f44fdd2f3eb0809d552f5632e4b41.1637799475.git.isaku.yamahata@intel.com>
Date:   Thu, 25 Nov 2021 21:11:45 +0100
Message-ID: <87mtlshu66.ffs@tglx>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

On Wed, Nov 24 2021 at 16:20, isaku yamahata wrote:

> From: Sean Christopherson <sean.j.christopherson@intel.com>
>
> Move the guts of vmx_cache_reg() to vt_cache_reg() in preparation for
> reusing the bulk of the code for TDX, which can access guest state for
> debug TDs.
>
> Use kvm_x86_ops.cache_reg() in ept_update_paging_mode_cr0() rather than
> trying to expose vt_cache_reg() to vmx.c, even though it means taking a
> retpoline.  The code runs if and only if EPT is enabled but unrestricted
> guest.

This sentence does not parse because it's not a proper sentence.

> Only one generation of CPU, Nehalem, supports EPT but not
> unrestricted guest, and disabling unrestricted guest without also
> disabling EPT is, to put it bluntly, dumb.

This one is only significantly better and lacks an explanation what this
means for the dumb case.

Thanks,

        tglx