From: Kai Huang <kai.huang@intel.com>
To: Isaku Yamahata <isaku.yamahata@gmail.com>,
Sathyanarayanan Kuppuswamy
<sathyanarayanan.kuppuswamy@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, Hans de Goede <hdegoede@redhat.com>,
Mark Gross <mgross@linux.intel.com>,
"H . Peter Anvin" <hpa@zytor.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
linux-kernel@vger.kernel.org,
platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH v3 4/4] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver
Date: Thu, 21 Apr 2022 22:33:09 +1200 [thread overview]
Message-ID: <48356d733067781b527fc0294317be27098f502d.camel@intel.com> (raw)
In-Reply-To: <20220421065707.GA1423762@private.email.ne.jp>
On Wed, 2022-04-20 at 23:57 -0700, Isaku Yamahata wrote:
> On Wed, Apr 20, 2022 at 07:42:06PM -0700,
> Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com> wrote:
>
> >
> >
> > On 4/20/22 5:11 PM, Kai Huang wrote:
> > > On Wed, 2022-04-20 at 16:45 -0700, Sathyanarayanan Kuppuswamy wrote:
> > > > If we want to support multiple GetQuote requests in parallel, then we
> > > > need some way to uniquely identify the GetQuote requests. So that when
> > > > we get completion notification, we can understand which request is
> > > > completed. This part is not mentioned/discussed in ABI spec. So we want
> > > > to serialize the requests for now.
> > > >
> > >
> > > Yes it's unfortunate that this part (whether concurrent GetQuote requests are
> > > supported by TDX architecture) is not explicitly mentioned in GHCI spec. I am
> > > fine with only supporting GetQuote requests one by one. AFAICT there's no
> > > request to support concurrent GetQuote requests anyway. What concerns me is
> > > exactly how explain this.
> > >
> > > As I said, we have GET_QUOTE_IN_FLIGHT flag now. Theoretically, you can queue
> > > multiple GetQuote requests, and when you receive the interrupt, you check which
> > > buffer has GET_QUOTE_IN_FLIGHT cleared. That buffer is the one with Quote
> > > ready. However I am not 100% sure whether above will always work. Interrupt
> > > can get lost when there are multiple Quotes ready in multiple buffer in very
> > > short time period, etc? Perhaps Isaku can provide more input here.
> >
> > Either supported or not, it should be mentioned in the GHCI spec. Currently,
> > there are no details related to it. If it is supported, the specification
> > should include the protocol to use.
> >
> > I will check with Isaku about it.
>
> The spec says that TD can call multiple GetQuote requests in parallel.
>
> TDG.VP.VMCALL<GetQuote> API allows one TD to issue multiple requests. It's
> implementation specific that how many concurrent requests are allowed. The TD
> should be able to handle TDG.VP.VMCALL_RETRY if it chooses to issue multiple
> requests simultaneously
>
> As Kai said, there is no requirement for multiple GetQuote in parallel, it's
> okay to support only single request at the same time.
>
> While the status is GET_QUOTE_IN_FLIGHT, VMM owns the shared GPA. The
> attestation driver should wait for GET_QUOTE_IN_FLIGHT to be cleared before
> sending next request.
Sorry I missed this in the spec. Then as I mentioned above, TD should check
which buffer has GET_QUOTE_IN_FLIGHT bit cleared to determine which GetQuote
request is done? I guess this is the only way.
Anyway, supporting single request only is fine to me. Just needs some
explanation in comments or commit message.
--
Thanks,
-Kai
next prev parent reply other threads:[~2022-04-21 10:33 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-15 22:01 [PATCH v3 0/4] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-04-15 22:01 ` [PATCH v3 1/4] x86/tdx: Add tdx_mcall_tdreport() API support Kuppuswamy Sathyanarayanan
2022-04-19 2:29 ` Kai Huang
2022-04-19 3:37 ` Sathyanarayanan Kuppuswamy
2022-04-19 3:51 ` Kai Huang
2022-04-19 3:53 ` Sathyanarayanan Kuppuswamy
2022-04-15 22:01 ` [PATCH v3 2/4] x86/tdx: Add tdx_hcall_get_quote() " Kuppuswamy Sathyanarayanan
2022-04-19 2:59 ` Kai Huang
2022-04-19 4:04 ` Sathyanarayanan Kuppuswamy
2022-04-19 4:40 ` Kai Huang
2022-04-19 5:28 ` Sathyanarayanan Kuppuswamy
2022-04-19 7:21 ` Kai Huang
2022-04-20 3:39 ` Aubrey Li
2022-04-20 7:16 ` Sathyanarayanan Kuppuswamy
2022-04-20 8:08 ` Aubrey Li
2022-04-22 17:24 ` Isaku Yamahata
2022-04-25 3:06 ` Aubrey Li
2022-04-15 22:01 ` [PATCH v3 3/4] x86/tdx: Add TDX Guest event notify interrupt support Kuppuswamy Sathyanarayanan
2022-04-15 22:01 ` [PATCH v3 4/4] platform/x86: intel_tdx_attest: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-04-19 7:47 ` Kai Huang
2022-04-19 8:13 ` Borislav Petkov
2022-04-19 12:48 ` Sathyanarayanan Kuppuswamy
2022-04-20 22:00 ` Borislav Petkov
2022-04-20 22:09 ` Sathyanarayanan Kuppuswamy
2022-04-21 9:10 ` Borislav Petkov
2022-04-21 14:54 ` Sathyanarayanan Kuppuswamy
2022-04-19 8:16 ` Kai Huang
2022-04-19 14:00 ` Sathyanarayanan Kuppuswamy
2022-04-19 22:38 ` Kai Huang
2022-04-19 14:13 ` Dave Hansen
2022-04-19 14:19 ` Sathyanarayanan Kuppuswamy
2022-04-19 14:24 ` Dave Hansen
2022-04-19 14:26 ` Sathyanarayanan Kuppuswamy
2022-04-19 22:21 ` Kai Huang
2022-04-19 22:49 ` Dave Hansen
2022-04-19 23:02 ` Kai Huang
2022-04-20 1:20 ` Isaku Yamahata
2022-04-20 1:26 ` Sathyanarayanan Kuppuswamy
2022-04-21 7:04 ` Isaku Yamahata
2022-04-21 14:44 ` Sathyanarayanan Kuppuswamy
2022-04-20 23:18 ` Kai Huang
2022-04-20 23:45 ` Sathyanarayanan Kuppuswamy
2022-04-21 0:11 ` Kai Huang
2022-04-21 2:42 ` Sathyanarayanan Kuppuswamy
2022-04-21 6:57 ` Isaku Yamahata
2022-04-21 10:33 ` Kai Huang [this message]
2022-04-21 14:53 ` Sathyanarayanan Kuppuswamy
2022-04-21 16:53 ` Isaku Yamahata
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