From: Dan Williams <dan.j.williams@intel.com>
To: Kai Huang <kai.huang@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
KVM list <kvm@vger.kernel.org>,
Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Brown, Len" <len.brown@intel.com>,
"Luck, Tony" <tony.luck@intel.com>,
Rafael J Wysocki <rafael.j.wysocki@intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Andi Kleen <ak@linux.intel.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
Isaku Yamahata <isaku.yamahata@intel.com>,
Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH v3 00/21] TDX host kernel support
Date: Thu, 5 May 2022 17:22:11 -0700 [thread overview]
Message-ID: <CAPcyv4jNYqPA2HBaO+9a+ije4jnb6a3Sx_1knrmRF9HCCXQuqg@mail.gmail.com> (raw)
In-Reply-To: <cbb2ea1343079aee546fb44cd59c82f66c875d76.camel@intel.com>
On Thu, May 5, 2022 at 3:14 PM Kai Huang <kai.huang@intel.com> wrote:
>
> Thanks for feedback!
>
> On Thu, 2022-05-05 at 06:51 -0700, Dan Williams wrote:
> > [ add Mike ]
> >
> >
> > On Thu, May 5, 2022 at 2:54 AM Kai Huang <kai.huang@intel.com> wrote:
> > [..]
> > >
> > > Hi Dave,
> > >
> > > Sorry to ping (trying to close this).
> > >
> > > Given we don't need to consider kmem-hot-add legacy PMEM after TDX module
> > > initialization, I think for now it's totally fine to exclude legacy PMEMs from
> > > TDMRs. The worst case is when someone tries to use them as TD guest backend
> > > directly, the TD will fail to create. IMO it's acceptable, as it is supposedly
> > > that no one should just use some random backend to run TD.
> >
> > The platform will already do this, right?
> >
>
> In the current v3 implementation, we don't have any code to handle memory
> hotplug, therefore nothing prevents people from adding legacy PMEMs as system
> RAM using kmem driver. In order to guarantee all pages managed by page
That's the fundamental question I am asking why is "guarantee all
pages managed by page allocator are TDX memory". That seems overkill
compared to indicating the incompatibility after the fact.
> allocator are all TDX memory, the v3 implementation needs to always include
> legacy PMEMs as TDX memory so that even people truly add legacy PMEMs as system
> RAM, we can still guarantee all pages in page allocator are TDX memory.
Why?
> Of course, a side benefit of always including legacy PMEMs is people
> theoretically can use them directly as TD guest backend, but this is just a
> bonus but not something that we need to guarantee.
>
>
> > I don't understand why this
> > is trying to take proactive action versus documenting the error
> > conditions and steps someone needs to take to avoid unconvertible
> > memory. There is already the CONFIG_HMEM_REPORTING that describes
> > relative performance properties between initiators and targets, it
> > seems fitting to also add security properties between initiators and
> > targets so someone can enumerate the numa-mempolicy that avoids
> > unconvertible memory.
>
> I don't think there's anything related to performance properties here. The only
> goal here is to make sure all pages in page allocator are TDX memory pages.
Please reconsider or re-clarify that goal.
>
> >
> > No, special casing in hotplug code paths needed.
> >
> > >
> > > I think w/o needing to include legacy PMEM, it's better to get all TDX memory
> > > blocks based on memblock, but not e820. The pages managed by page allocator are
> > > from memblock anyway (w/o those from memory hotplug).
> > >
> > > And I also think it makes more sense to introduce 'tdx_memblock' and
> > > 'tdx_memory' data structures to gather all TDX memory blocks during boot when
> > > memblock is still alive. When TDX module is initialized during runtime, TDMRs
> > > can be created based on the 'struct tdx_memory' which contains all TDX memory
> > > blocks we gathered based on memblock during boot. This is also more flexible to
> > > support other TDX memory from other sources such as CLX memory in the future.
> > >
> > > Please let me know if you have any objection? Thanks!
> >
> > It's already the case that x86 maintains sideband structures to
> > preserve memory after exiting the early memblock code.
> >
>
> May I ask what data structures are you referring to?
struct numa_meminfo.
> Btw, the purpose of 'tdx_memblock' and 'tdx_memory' is not only just to preserve
> memblock info during boot. It is also used to provide a common data structure
> that the "constructing TDMRs" code can work on. If you look at patch 11-14, the
> logic (create TDMRs, allocate PAMTs, sets up reserved areas) around how to
> construct TDMRs doesn't have hard dependency on e820. If we construct TDMRs
> based on a common 'tdx_memory' like below:
>
> int construct_tdmrs(struct tdx_memory *tmem, ...);
>
> It would be much easier to support other TDX memory resources in the future.
"in the future" is a prompt to ask "Why not wait until that future /
need arrives before adding new infrastructure?"
> The thing I am not sure is Dave wants to keep the code minimal (as this series
> is already very big in terms of LoC) to make TDX running, and for now in
> practice there's only system RAM during boot is TDX capable, so I am not sure we
> should introduce those structures now.
>
> > Mike, correct
> > me if I am wrong, but adding more is less desirable than just keeping
> > the memblock around?
next prev parent reply other threads:[~2022-05-06 0:22 UTC|newest]
Thread overview: 156+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-06 4:49 [PATCH v3 00/21] TDX host kernel support Kai Huang
2022-04-06 4:49 ` [PATCH v3 01/21] x86/virt/tdx: Detect SEAM Kai Huang
2022-04-18 22:29 ` Sathyanarayanan Kuppuswamy
2022-04-18 22:50 ` Sean Christopherson
2022-04-19 3:38 ` Kai Huang
2022-04-26 20:21 ` Dave Hansen
2022-04-26 23:12 ` Kai Huang
2022-04-26 23:28 ` Dave Hansen
2022-04-26 23:49 ` Kai Huang
2022-04-27 0:22 ` Sean Christopherson
2022-04-27 0:44 ` Kai Huang
2022-04-27 14:22 ` Dave Hansen
2022-04-27 22:39 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 02/21] x86/virt/tdx: Detect TDX private KeyIDs Kai Huang
2022-04-19 5:39 ` Sathyanarayanan Kuppuswamy
2022-04-19 9:41 ` Kai Huang
2022-04-19 5:42 ` Sathyanarayanan Kuppuswamy
2022-04-19 10:07 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 03/21] x86/virt/tdx: Implement the SEAMCALL base function Kai Huang
2022-04-19 14:07 ` Sathyanarayanan Kuppuswamy
2022-04-20 4:16 ` Kai Huang
2022-04-20 7:29 ` Sathyanarayanan Kuppuswamy
2022-04-20 10:39 ` Kai Huang
2022-04-26 20:37 ` Dave Hansen
2022-04-26 23:29 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 04/21] x86/virt/tdx: Add skeleton for detecting and initializing TDX on demand Kai Huang
2022-04-19 14:53 ` Sathyanarayanan Kuppuswamy
2022-04-20 4:37 ` Kai Huang
2022-04-20 5:21 ` Dave Hansen
2022-04-20 14:30 ` Sathyanarayanan Kuppuswamy
2022-04-20 22:35 ` Kai Huang
2022-04-26 20:53 ` Dave Hansen
2022-04-27 0:43 ` Kai Huang
2022-04-27 14:49 ` Dave Hansen
2022-04-28 0:00 ` Kai Huang
2022-04-28 14:27 ` Dave Hansen
2022-04-28 23:44 ` Kai Huang
2022-04-28 23:53 ` Dave Hansen
2022-04-29 0:11 ` Kai Huang
2022-04-29 0:26 ` Dave Hansen
2022-04-29 0:59 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 05/21] x86/virt/tdx: Detect P-SEAMLDR and TDX module Kai Huang
2022-04-26 20:56 ` Dave Hansen
2022-04-27 0:01 ` Kai Huang
2022-04-27 14:24 ` Dave Hansen
2022-04-27 21:30 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 06/21] x86/virt/tdx: Shut down TDX module in case of error Kai Huang
2022-04-23 15:39 ` Sathyanarayanan Kuppuswamy
2022-04-25 23:41 ` Kai Huang
2022-04-26 1:48 ` Sathyanarayanan Kuppuswamy
2022-04-26 2:12 ` Kai Huang
2022-04-26 20:59 ` Dave Hansen
2022-04-27 0:06 ` Kai Huang
2022-05-18 16:19 ` Sagi Shahar
2022-05-18 23:51 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 07/21] x86/virt/tdx: Do TDX module global initialization Kai Huang
2022-04-20 22:27 ` Sathyanarayanan Kuppuswamy
2022-04-20 22:37 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 08/21] x86/virt/tdx: Do logical-cpu scope TDX module initialization Kai Huang
2022-04-24 1:27 ` Sathyanarayanan Kuppuswamy
2022-04-25 23:55 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 09/21] x86/virt/tdx: Get information about TDX module and convertible memory Kai Huang
2022-04-25 2:58 ` Sathyanarayanan Kuppuswamy
2022-04-26 0:05 ` Kai Huang
2022-04-27 22:15 ` Dave Hansen
2022-04-28 0:15 ` Kai Huang
2022-04-28 14:06 ` Dave Hansen
2022-04-28 23:14 ` Kai Huang
2022-04-29 17:47 ` Dave Hansen
2022-05-02 5:04 ` Kai Huang
2022-05-25 4:47 ` Kai Huang
2022-05-25 4:57 ` Kai Huang
2022-05-25 16:00 ` Kai Huang
2022-05-18 22:30 ` Sagi Shahar
2022-05-18 23:56 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 10/21] x86/virt/tdx: Add placeholder to coveret all system RAM as TDX memory Kai Huang
2022-04-20 20:48 ` Isaku Yamahata
2022-04-20 22:38 ` Kai Huang
2022-04-27 22:24 ` Dave Hansen
2022-04-28 0:53 ` Kai Huang
2022-04-28 1:07 ` Dave Hansen
2022-04-28 1:35 ` Kai Huang
2022-04-28 3:40 ` Dave Hansen
2022-04-28 3:55 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 11/21] x86/virt/tdx: Choose to use " Kai Huang
2022-04-20 20:55 ` Isaku Yamahata
2022-04-20 22:39 ` Kai Huang
2022-04-28 15:54 ` Dave Hansen
2022-04-29 7:32 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 12/21] x86/virt/tdx: Create TDMRs to cover all system RAM Kai Huang
2022-04-28 16:22 ` Dave Hansen
2022-04-29 7:24 ` Kai Huang
2022-04-29 13:52 ` Dave Hansen
2022-04-06 4:49 ` [PATCH v3 13/21] x86/virt/tdx: Allocate and set up PAMTs for TDMRs Kai Huang
2022-04-28 17:12 ` Dave Hansen
2022-04-29 7:46 ` Kai Huang
2022-04-29 14:20 ` Dave Hansen
2022-04-29 14:30 ` Sean Christopherson
2022-04-29 17:46 ` Dave Hansen
2022-04-29 18:19 ` Sean Christopherson
2022-04-29 18:32 ` Dave Hansen
2022-05-02 5:59 ` Kai Huang
2022-05-02 14:17 ` Dave Hansen
2022-05-02 21:55 ` Kai Huang
2022-04-06 4:49 ` [PATCH v3 14/21] x86/virt/tdx: Set up reserved areas for all TDMRs Kai Huang
2022-04-06 4:49 ` [PATCH v3 15/21] x86/virt/tdx: Reserve TDX module global KeyID Kai Huang
2022-04-06 4:49 ` [PATCH v3 16/21] x86/virt/tdx: Configure TDX module with TDMRs and " Kai Huang
2022-04-06 4:49 ` [PATCH v3 17/21] x86/virt/tdx: Configure global KeyID on all packages Kai Huang
2022-04-06 4:49 ` [PATCH v3 18/21] x86/virt/tdx: Initialize all TDMRs Kai Huang
2022-04-06 4:49 ` [PATCH v3 19/21] x86: Flush cache of TDX private memory during kexec() Kai Huang
2022-04-06 4:49 ` [PATCH v3 20/21] x86/virt/tdx: Add kernel command line to opt-in TDX host support Kai Huang
2022-04-28 17:25 ` Dave Hansen
2022-04-06 4:49 ` [PATCH v3 21/21] Documentation/x86: Add documentation for " Kai Huang
2022-04-14 10:19 ` [PATCH v3 00/21] TDX host kernel support Kai Huang
2022-04-26 20:13 ` Dave Hansen
2022-04-27 1:15 ` Kai Huang
2022-04-27 21:59 ` Dave Hansen
2022-04-28 0:37 ` Kai Huang
2022-04-28 0:50 ` Dave Hansen
2022-04-28 0:58 ` Kai Huang
2022-04-29 1:40 ` Kai Huang
2022-04-29 3:04 ` Dan Williams
2022-04-29 5:35 ` Kai Huang
2022-05-03 23:59 ` Kai Huang
2022-05-04 0:25 ` Dave Hansen
2022-05-04 1:15 ` Kai Huang
2022-05-05 9:54 ` Kai Huang
2022-05-05 13:51 ` Dan Williams
2022-05-05 22:14 ` Kai Huang
2022-05-06 0:22 ` Dan Williams [this message]
2022-05-06 0:45 ` Kai Huang
2022-05-06 1:15 ` Dan Williams
2022-05-06 1:46 ` Kai Huang
2022-05-06 15:57 ` Dan Williams
2022-05-09 2:46 ` Kai Huang
2022-05-10 10:25 ` Kai Huang
2022-05-07 0:09 ` Mike Rapoport
2022-05-08 10:00 ` Kai Huang
2022-05-09 10:33 ` Mike Rapoport
2022-05-09 23:27 ` Kai Huang
2022-05-04 14:31 ` Dan Williams
2022-05-04 22:50 ` Kai Huang
2022-04-28 1:01 ` Dan Williams
2022-04-28 1:21 ` Kai Huang
2022-04-29 2:58 ` Dan Williams
2022-04-29 5:43 ` Kai Huang
2022-04-29 14:39 ` Dave Hansen
2022-04-29 15:18 ` Dan Williams
2022-04-29 17:18 ` Dave Hansen
2022-04-29 17:48 ` Dan Williams
2022-04-29 18:34 ` Dave Hansen
2022-04-29 18:47 ` Dan Williams
2022-04-29 19:20 ` Dave Hansen
2022-04-29 21:20 ` Dan Williams
2022-04-29 21:27 ` Dave Hansen
2022-05-02 10:18 ` Kai Huang
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