From: Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>,
Kai Huang <kai.huang@intel.com>,
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, "H . Peter Anvin" <hpa@zytor.com>,
Tony Luck <tony.luck@intel.com>, Andi Kleen <ak@linux.intel.com>,
Wander Lairson Costa <wander@redhat.com>,
Isaku Yamahata <isaku.yamahata@gmail.com>,
marcelo.cerri@canonical.com, tim.gardner@canonical.com,
khalid.elmously@canonical.com, philip.cox@canonical.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] x86/tdx: Add Quote generation support
Date: Mon, 9 May 2022 08:43:03 -0700 [thread overview]
Message-ID: <09b28e14-cb55-6945-bc03-7554e5e6ae61@linux.intel.com> (raw)
In-Reply-To: <20220509153534.i6v4xcb2g24ia2i4@black.fi.intel.com>
On 5/9/22 8:35 AM, Kirill A. Shutemov wrote:
> On Mon, May 09, 2022 at 07:14:20AM -0700, Dave Hansen wrote:
>> On 5/9/22 05:09, Kirill A. Shutemov wrote:
>>> Private->Shared conversion is destructive. You have to split SEPT, flush
>>> TLB. Backward conversion even more costly.
>>>
>>> Rule of thumb is avoid conversion where possible. DMA API is there for
>>> you.
>>
>> Kirill, I understand that the DMA API is a quick fix today. But is it
>> _really_ the right long-term interface?
>
> Yes, I think so.
>
>> There will surely come a time when TDX I/O devices won't be using fixed
>> bounce buffers. What will the quote generation code do then? How will
>> we know to come back around and fix this up?
>
> VirtIO will not go away with TDX I/O in picture. TDX I/O will be addition
> to existing stuff, not replacement.
>
> And we have hooks in place to accommodate this: force_dma_unencrypted()
> will return false for devices capable of TDX I/O. While the rest of
> devices, including VirtIO and attestation, keep using existing paths with
> swiotlb.
>
>> Does SEV or the s390 ultravisor need anything like this?
>
> At quick glance sev-guest.c uses set_memory_decrypted()/encrypted() for
> allocation and freeing shared memory. I consider it inferior to using DMA
> API.
Following is the link for the SEV attestation driver. It does seem to
use alloc_pages() and set_memory_*() calls.
https://lore.kernel.org/lkml/20220307215344.2799259-1-brijesh.singh@amd.com/
>
--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer
next prev parent reply other threads:[~2022-05-09 15:43 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-01 18:34 [PATCH v5 0/3] Add TDX Guest Attestation support Kuppuswamy Sathyanarayanan
2022-05-01 18:34 ` [PATCH v5 1/3] x86/tdx: Add TDX Guest attestation interface driver Kuppuswamy Sathyanarayanan
2022-05-02 2:31 ` Kai Huang
2022-05-02 15:52 ` Sathyanarayanan Kuppuswamy
2022-05-02 22:30 ` Kai Huang
2022-05-02 23:17 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:37 ` Kai Huang
2022-05-03 14:38 ` Wander Costa
2022-05-03 15:09 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:08 ` Kai Huang
2022-05-02 12:18 ` Wander Lairson Costa
2022-05-02 16:06 ` Sathyanarayanan Kuppuswamy
2022-05-01 18:34 ` [PATCH v5 2/3] x86/tdx: Add TDX Guest event notify interrupt support Kuppuswamy Sathyanarayanan
2022-05-02 12:44 ` Wander Lairson Costa
2022-05-01 18:35 ` [PATCH v5 3/3] x86/tdx: Add Quote generation support Kuppuswamy Sathyanarayanan
2022-05-02 2:40 ` Kai Huang
2022-05-03 1:27 ` Kirill A. Shutemov
2022-05-03 2:18 ` Kai Huang
2022-05-03 2:39 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:13 ` Kai Huang
2022-05-03 2:45 ` Kirill A. Shutemov
2022-05-03 3:36 ` Kai Huang
2022-05-03 22:24 ` Dave Hansen
2022-05-03 22:28 ` Sathyanarayanan Kuppuswamy
2022-05-03 22:30 ` Sathyanarayanan Kuppuswamy
2022-05-04 22:49 ` Sathyanarayanan Kuppuswamy
2022-05-04 23:28 ` Kai Huang
2022-05-05 20:53 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:15 ` Kai Huang
2022-05-05 22:38 ` Sathyanarayanan Kuppuswamy
2022-05-05 23:06 ` Dave Hansen
2022-05-06 0:11 ` Kai Huang
2022-05-06 1:55 ` Sathyanarayanan Kuppuswamy
2022-05-07 0:42 ` Kirill A. Shutemov
2022-05-09 3:37 ` Kai Huang
2022-05-09 12:09 ` Kirill A. Shutemov
2022-05-09 14:14 ` Dave Hansen
2022-05-09 15:35 ` Kirill A. Shutemov
2022-05-09 15:43 ` Sathyanarayanan Kuppuswamy [this message]
2022-05-09 23:54 ` Kai Huang
2022-05-10 0:17 ` Sathyanarayanan Kuppuswamy
2022-05-10 1:30 ` Kirill A. Shutemov
2022-05-10 1:40 ` Kai Huang
2022-05-10 10:42 ` Kai Huang
2022-05-16 17:39 ` Sathyanarayanan Kuppuswamy
2022-05-06 11:00 ` Kai Huang
2022-05-06 15:47 ` Dave Hansen
2022-05-07 1:00 ` Kirill A. Shutemov
2022-05-05 10:50 ` Kai Huang
2022-05-05 19:03 ` Sathyanarayanan Kuppuswamy
2022-05-05 22:25 ` Kai Huang
2022-05-02 5:01 ` Kai Huang
2022-05-02 16:02 ` Sathyanarayanan Kuppuswamy
2022-05-02 23:02 ` Kai Huang
2022-05-02 13:16 ` Wander Lairson Costa
2022-05-02 16:05 ` Sathyanarayanan Kuppuswamy
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