From: Alexey Kardashevskiy <aik@amd.com>
To: Peter Gonda <pgonda@google.com>,
Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
linux-coco@lists.linux.dev, Borislav Petkov <bp@alien8.de>,
Tom Lendacky <thomas.lendacky@amd.com>,
Brijesh Singh <brijesh.singh@amd.com>,
Jeremi Piotrowski <jpiotrowski@linux.microsoft.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@linux.intel.com>,
peterz@infradead.org, dave.hansen@linux.intel.com
Subject: Re: [PATCH v6 6/7] virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT
Date: Tue, 17 Oct 2023 11:42:30 +1100 [thread overview]
Message-ID: <9c55ef4f-181b-4370-8444-dd0b02ba317a@amd.com> (raw)
In-Reply-To: <CAMkAt6p_mTKrzzQGqzMPB9FU9Nqy9yLJ_tCqFQQ7Q_W12XCkJg@mail.gmail.com>
On 17/10/23 02:42, Peter Gonda wrote:
> On Mon, Oct 16, 2023 at 9:39 AM Dionna Amalie Glaze
> <dionnaglaze@google.com> wrote:
>>
>>>> +
>>>> + struct snp_guest_request_ioctl input = {
>>>> + .msg_version = 1,
>>>> + .req_data = (__u64)&ext_req,
>>>> + .resp_data = (__u64)buf,
>>>> + .exitinfo2 = 0xff,
>>>
>>> Not sure we need this line with 0xff.
>>>
>>
>> The exitinfo2 value had an uninitialized memory bug, where random data
>> would get returned to user space. I think this is carrying forward the
>> initial value that sev-guest currently uses.
>
> I think during the initial review I asked for exitinfo2 to be set to
> some known value initially.
> That way userspace can tell if the request
> failed before the ASP was involved.
ASP or HV? SEV-SNP ABI or GHCB? It is possible to make a GHCB call and
have KVM write something in exit_info_2 without calling the ASP. The
guest should really look into the encrypted response buffer to know what
really happened.
Anyway, looks like "rio->exitinfo2 = SEV_RET_NO_FW_CALL" in
snp_issue_guest_request() is supposed to handle this. 0xff in
snp_guest_ioctl() seems to be for something else. May be
s/0xff/SEV_RET_NO_FW_CALL/. And I do not really see why the userspace
could not write this 0xff to @input itself before doing ioctl().
The efb339a83368ab25de log is ambiguous btw -
"The PSP can return ... in circumstances where the PSP has not actually
been called" - if something is not called - it cannot possibly return :)
Thanks,
>>
>> --
>> -Dionna Glaze, PhD (she/her)
>>
--
Alexey
next prev parent reply other threads:[~2023-10-17 0:43 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-13 2:13 [PATCH v6 0/7] configfs-tsm: Attestation Report ABI Dan Williams
2023-10-13 2:14 ` [PATCH v6 1/7] virt: sevguest: Fix passing a stack buffer as a scatterlist target Dan Williams
2023-10-13 2:14 ` [PATCH v6 2/7] virt: coco: Add a coco/Makefile and coco/Kconfig Dan Williams
2023-10-13 2:14 ` [PATCH v6 3/7] configfs-tsm: Introduce a shared ABI for attestation reports Dan Williams
2023-10-13 4:43 ` Dionna Amalie Glaze
2023-10-13 5:15 ` Dan Williams
2023-10-16 6:36 ` Alexey Kardashevskiy
2023-10-17 2:19 ` Dan Williams
2023-10-17 6:20 ` Alexey Kardashevskiy
2023-10-19 1:29 ` Dan Williams
2023-10-19 20:24 ` Dan Williams
2023-10-13 2:14 ` [PATCH v6 4/7] virt: sevguest: Prep for kernel internal get_ext_report() Dan Williams
2023-10-13 2:14 ` [PATCH v6 5/7] mm/slab: Add __free() support for kvfree Dan Williams
2023-10-13 2:14 ` [PATCH v6 6/7] virt: sevguest: Add TSM_REPORTS support for SNP_GET_EXT_REPORT Dan Williams
2023-10-13 15:38 ` Tom Lendacky
2023-10-14 4:46 ` Dan Williams
2023-10-16 11:36 ` Alexey Kardashevskiy
2023-10-16 15:39 ` Dionna Amalie Glaze
2023-10-16 15:42 ` Peter Gonda
2023-10-17 0:42 ` Alexey Kardashevskiy [this message]
2023-10-19 4:30 ` Dan Williams
2023-10-17 4:07 ` Dan Williams
2023-10-17 5:35 ` Alexey Kardashevskiy
2023-10-17 6:28 ` Alexey Kardashevskiy
2023-10-19 4:43 ` Dan Williams
2023-10-19 5:12 ` Alexey Kardashevskiy
2023-10-19 3:34 ` Dan Williams
2023-10-13 2:14 ` [PATCH v6 7/7] virt: tdx-guest: Add Quote generation support using TSM_REPORTS Dan Williams
2023-10-19 18:12 ` Peter Gonda
2023-10-13 15:39 ` [PATCH v6 0/7] configfs-tsm: Attestation Report ABI Tom Lendacky
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