linux-kernel - Re: [PATCH v5 0/9] Enable Sub-page Write Protection Support

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Message-ID: <20190917125904.GB22162@char.us.oracle.com>
Date:   Tue, 17 Sep 2019 08:59:04 -0400
From:   Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        pbonzini@...hat.com, sean.j.christopherson@...el.com,
        mst@...hat.com, rkrcmar@...hat.com, jmattson@...gle.com,
        yu.c.zhang@...el.com, alazar@...defender.com
Subject: Re: [PATCH v5 0/9] Enable Sub-page Write Protection Support

On Tue, Sep 17, 2019 at 04:52:55PM +0800, Yang Weijiang wrote:
> EPT-Based Sub-Page write Protection(SPP)is a HW capability which allows
> Virtual Machine Monitor(VMM) to specify write-permission for guest
> physical memory at a sub-page(128 byte) granularity. When this
> capability is enabled, the CPU enforces write-access check for sub-pages
> within a 4KB page.
> 
> The feature is targeted to provide fine-grained memory protection for
> usages such as device virtualization, memory check-point and VM
> introspection etc.
> 
> SPP is active when the "sub-page write protection" (bit 23) is 1 in
> Secondary VM-Execution Controls. The feature is backed with a Sub-Page
> Permission Table(SPPT), SPPT is referenced via a 64-bit control field
> called Sub-Page Permission Table Pointer (SPPTP) which contains a
> 4K-aligned physical address.
> 
> To enable SPP for certain physical page, the gfn should be first mapped
> to a 4KB entry, then set bit 61 of the corresponding EPT leaf entry. 
> While HW walks EPT, if bit 61 is set, it traverses SPPT with the guset
> physical address to find out the sub-page permissions at the leaf entry.
> If the corresponding bit is set, write to sub-page is permitted,
> otherwise, SPP induced EPT violation is generated.
> 
> This patch serial passed SPP function test and selftest on Ice-Lake platform.
> 
> Please refer to the SPP introduction document in this patch set and
> Intel SDM for details:
> 
> Intel SDM:
> https://software.intel.com/sites/default/files/managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf
> 
> SPP selftest patch:
> https://lkml.org/lkml/2019/6/18/1197
> 
> Previous patch:
> https://lkml.org/lkml/2019/8/14/97

I saw the patches as part of the introspection patch-set.
Are you all working together on this?

Would it be possible for some of the bitdefender folks who depend on this
to provide Tested-by adn could they also take the time to review this patch-set?

Thanks.