From: Dave Hansen <dave.hansen@intel.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
"sashiko-reviews@lists.linux.dev"
<sashiko-reviews@lists.linux.dev>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-coco@lists.linux.dev" <linux-coco@lists.linux.dev>,
"Huang, Kai" <kai.huang@intel.com>,
"Zhao, Yan Y" <yan.y.zhao@intel.com>,
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"Wu, Binbin" <binbin.wu@intel.com>,
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Subject: Re: [PATCH v9 04/11] x86/virt/tdx: Allocate refcounts for Dynamic PAMT memory
Date: Thu, 6 Aug 2026 15:09:54 -0700 [thread overview]
Message-ID: <61e51e6d-1f41-44a8-ad68-837e1d3b5609@intel.com> (raw)
In-Reply-To: <fd3014be925bc16fb3e1522c8cce00d9149e7808.camel@intel.com>
On 8/6/26 15:02, Edgecombe, Rick P wrote:
> On Thu, 2026-08-06 at 02:21 +0000, sashiko-bot@kernel.org wrote:
>> [Severity: High]
>> Could this vzalloc() call trigger a kernel panic on systems with sparse
>> memory layouts instead of gracefully disabling TDX?
...
> I think this is a bit overblown. If there is a lot of memory such that this
> allocation is large, we can expect it be less likely to fail.
Yes, it could trigger a kernel panic. And, yes, sashiko's concern is
overblown.
This code only runs on the host side, so there's no exotic VM craziness.
In reality, today, there are not many TDX systems. The ones that do
exist don't have exotic sparse memory layouts either. TDX also doesn't
yet support any of the emerging memory technologies like CXL.mem that
might lead to bare-metal weirdo layouts.
But even in a future with a pathologically evil memory layout, is anyone
going to miss 8GB of memory on a server? Probably not.
So, yeah, I just don't see the point of going crazy over this. If
someone hits this in 10 years, we'll fix it then. Oooh, maybe I'll be
retired in 10 years. One can dream.
next prev parent reply other threads:[~2026-08-06 22:10 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-06 2:08 [PATCH v9 00/11] Dynamic PAMT Rick Edgecombe
2026-08-06 2:08 ` [PATCH v9 01/11] x86/virt/tdx: Simplify PAMT layout calculation Rick Edgecombe
2026-08-06 20:58 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 02/11] x86/virt/tdx: Allocate page bitmap for Dynamic PAMT Rick Edgecombe
2026-08-06 20:58 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 03/11] x86/virt/tdx: Add tdx_alloc/free_control_page() helpers Rick Edgecombe
2026-08-06 17:17 ` Dave Hansen
2026-08-06 17:20 ` Dave Hansen
2026-08-06 22:22 ` Edgecombe, Rick P
2026-08-06 22:42 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 04/11] x86/virt/tdx: Allocate refcounts for Dynamic PAMT memory Rick Edgecombe
2026-08-06 20:56 ` Dave Hansen
2026-08-06 21:56 ` Edgecombe, Rick P
[not found] ` <20260806022158.586A11F000E9@smtp.kernel.org>
2026-08-06 22:02 ` Edgecombe, Rick P
2026-08-06 22:09 ` Dave Hansen [this message]
2026-08-06 2:08 ` [PATCH v9 05/11] x86/virt/tdx: Handle multiple callers in tdx_pamt_get/put() Rick Edgecombe
2026-08-06 22:17 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 06/11] KVM: TDX: Allocate PAMT memory for TD and vCPU control structures Rick Edgecombe
2026-08-06 22:19 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 07/11] x86/tdx: Add APIs to support Dynamic PAMT ops from KVM's fault path Rick Edgecombe
2026-08-06 22:19 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 08/11] KVM: TDX: Get/put PAMT pages when (un)mapping private memory Rick Edgecombe
2026-08-06 23:48 ` Dave Hansen
2026-08-06 2:08 ` [PATCH v9 09/11] x86/virt/tdx: Enable Dynamic PAMT Rick Edgecombe
2026-08-06 2:08 ` [PATCH v9 10/11] Documentation/x86: Add documentation for TDX's " Rick Edgecombe
2026-08-06 2:08 ` [PATCH v9 11/11] x86/virt/tdx: Optimize tdx_pamt_get/put() Rick Edgecombe
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