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From: Dan Williams <dan.j.williams@intel.com>
To: Andi Kleen <ak@linux.intel.com>
Cc: "Kuppuswamy,
	Sathyanarayanan"  <sathyanarayanan.kuppuswamy@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>,
	Hans de Goede <hdegoede@redhat.com>,
	Mark Gross <mgross@linux.intel.com>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Peter H Anvin <hpa@zytor.com>,
	Dave Hansen <dave.hansen@intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Kirill Shutemov <kirill.shutemov@linux.intel.com>,
	Sean Christopherson <seanjc@google.com>,
	Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
	X86 ML <x86@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	platform-driver-x86@vger.kernel.org, bpf@vger.kernel.org,
	Netdev <netdev@vger.kernel.org>
Subject: Re: [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver
Date: Thu, 8 Jul 2021 18:37:26 -0700	[thread overview]
Message-ID: <CAPcyv4gwsT4rJzemkofk6SP5cAp9=nr5T6vtu+i6wTbU91R_Bg@mail.gmail.com> (raw)
In-Reply-To: <4972fc1a-1ffb-2b6d-e764-471210df96a3@linux.intel.com>

On Thu, Jul 8, 2021 at 5:36 PM Andi Kleen <ak@linux.intel.com> wrote:
>
>
> On 7/8/2021 5:20 PM, Dan Williams wrote:
> >
> > If you have a lock would TDX KVM even notice that its parallel
> > requests are being handled serially? I.e. even if they said "yes,
> > multiple requests may happen in parallel", until it becomes an actual
> > latency problem in practice it's not clear that this generous use of
> > resources is justified.
> The worst case usage is 2 pages * file descriptor. There are lots of
> other ways to use that much and more memory for each file descriptor.
>
> >
> > Scratch that... this driver already has the attestation_lock! So, it's
> > already the case that only one thread can be attesting at a time. The
> > per-file buffer is unecessary.
>
> But then you couldn't free the buffer. So it would be leaked forever for
> likely only one attestation.
>
> Not sure what problem you're trying to solve here.

One allocation for the life of the driver that can have its direct map
permissions changed rather than an allocation per-file descriptor and
fragmenting the direct map.

> > keyutils supports generating and passing blobs into and out of the
> > kernel with a handle associated to those blobs. This driver adds a TDX
> > way to pass blobs into and out of the kernel. If Linux grows other
> > TDX-like attestation requirements in the future (e.g. PCI SPDM) should
> > each of those invent their own user ABI for passing blobs around?
>
> The TDX blobs are different than any blobs that keyutils supports today.
> The TDX operations are different too.
>
> TDREPORT doesn't even involve any keys, it's just attestation reports.
>
> keyutils today nothing related to attestation.
>
> I just don't see any commonality. If there was commonality it would be
> more with the TPM interface, but TDX attestation is different enough
> that it also isn't feasible to directly convert it into TPM operation
> (apart from standard TPM being a beast that you better avoid as much as
> possible anyways)
>

Ok. I'll leave that alone for TDX, but I still have my eyes on
keyutils for aspects of PCI SPDM.

  reply	other threads:[~2021-07-09  1:37 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-07 20:42 [PATCH v2 0/6] Add TDX Guest Support (Attestation support) Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 1/6] x86/tdx: Add TDREPORT TDX Module call support Kuppuswamy Sathyanarayanan
2021-07-08  8:16   ` Xiaoyao Li
2021-07-08 14:07     ` Kuppuswamy, Sathyanarayanan
2021-07-08 14:20       ` Hans de Goede
2021-07-08 17:06         ` Kuppuswamy, Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 2/6] x86/tdx: Add GetQuote TDX hypercall support Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 3/6] x86/tdx: Add SetupEventNotifyInterrupt " Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 4/6] x86/tdx: Add TDX Guest event notify interrupt vector support Kuppuswamy Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2021-07-08 22:21   ` Andy Lutomirski
2021-07-08 22:35     ` Dave Hansen
2021-07-09  0:38       ` Andi Kleen
2021-07-13  0:33         ` Kuppuswamy, Sathyanarayanan
2021-07-13  0:44           ` Dave Hansen
2021-07-08 23:34     ` Kuppuswamy, Sathyanarayanan
2021-07-08 23:36   ` Dan Williams
2021-07-08 23:57     ` Kuppuswamy, Sathyanarayanan
2021-07-09  0:20       ` Dan Williams
2021-07-09  0:36         ` Andi Kleen
2021-07-09  1:37           ` Dan Williams [this message]
2021-07-09  1:44             ` Andi Kleen
2021-07-09  2:04               ` Dan Williams
2021-07-09  2:43                 ` Kuppuswamy, Sathyanarayanan
2021-07-07 20:42 ` [PATCH v2 6/6] tools/tdx: Add a sample attestation user app Kuppuswamy Sathyanarayanan
2021-07-15  8:36   ` Mian Yousaf Kaukab
2021-07-15 15:19     ` Kuppuswamy, Sathyanarayanan
2022-03-30 22:17 [PATCH v2 0/6] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-03-30 22:18 ` [PATCH v2 5/6] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-04-04 10:07   ` Hans de Goede
2022-04-04 19:56     ` Sathyanarayanan Kuppuswamy
2022-04-11 14:38       ` Hans de Goede
2022-04-04 10:09   ` Hans de Goede
2022-04-04 10:11     ` Hans de Goede

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