linux-kernel - Re: [PATCH v8 11/16] x86/virt/tdx: Designate reserved areas for all TDMRs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <24ea02aa4db7d470adeb7a64b7692d8bd5a428ca.camel@intel.com>
Date:   Tue, 10 Jan 2023 11:01:36 +0000
From:   "Huang, Kai" <kai.huang@...el.com>
To:     "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     "Luck, Tony" <tony.luck@...el.com>,
        "bagasdotme@...il.com" <bagasdotme@...il.com>,
        "ak@...ux.intel.com" <ak@...ux.intel.com>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        "kirill.shutemov@...ux.intel.com" <kirill.shutemov@...ux.intel.com>,
        "Christopherson,, Sean" <seanjc@...gle.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "Yamahata, Isaku" <isaku.yamahata@...el.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "Shahar, Sagi" <sagis@...gle.com>,
        "imammedo@...hat.com" <imammedo@...hat.com>,
        "Gao, Chao" <chao.gao@...el.com>,
        "Brown, Len" <len.brown@...el.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        "Huang, Ying" <ying.huang@...el.com>,
        "Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v8 11/16] x86/virt/tdx: Designate reserved areas for all
 TDMRs

On Mon, 2023-01-09 at 17:22 -0800, Dave Hansen wrote:
> On 1/9/23 17:19, Huang, Kai wrote:
> > > It's probably also worth noting *somewhere* that there's a balance to be
> > > had between TDMRs and reserved areas.  A system that is running out of
> > > reserved areas in a TDMR could split a TDMR to get more reserved areas.
> > > A system that has run out of TDMRs could relatively easily coalesce two
> > > adjacent TDMRs (before the PAMTs are allocated) and use a reserved area
> > > if there was a gap between them.
> > We can add above to the changelog of this patch, or the patch 09 ("x86/virt/tdx:
> > Fill out TDMRs to cover all TDX memory regions").  The latter perhaps is better
> > since that patch is the first place where the balance of TDMRs and reserved
> > areas is related.
> > 
> > What is your suggestion?
> 
> Just put it close to the code that actually hits the problem so the
> potential solution is close at hand to whoever hits the problem.
> 

Sorry to double check: the code which hits the problem is the 'if (idx >=
max_reserved_per_tdmr)' check in tdmr_add_rsvd_area(), so I think I can add
right before this check?