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Subject: Re: [6.4-rc6] Crash during a kexec operation
 (tpm_amd_is_rng_defective)
From:   Sachin Sant <sachinp@linux.ibm.com>
In-Reply-To: <3f5a37f1-70e0-3dcf-3bd3-acc8a04e53ee@amd.com>
Date:   Fri, 23 Jun 2023 08:22:04 +0530
Cc:     Michael Ellerman <mpe@ellerman.id.au>,
        Linux regressions mailing list <regressions@lists.linux.dev>,
        open list <linux-kernel@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, jarkko@kernel.org,
        linux-integrity@vger.kernel.org,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
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Message-Id: <425CE5FE-FE54-493D-A74E-7EBC812544BB@linux.ibm.com>
References: <99B81401-DB46-49B9-B321-CF832B50CAC3@linux.ibm.com>
 <87o7lhfmoh.fsf@mail.lhotse>
 <CA0088E4-2851-4AFF-94F8-2A07C5CDA8D8@linux.ibm.com>
 <675a8893-429d-05be-b647-089b249c814c@leemhuis.info>
 <87o7l7oer1.fsf@mail.lhotse> <3f5a37f1-70e0-3dcf-3bd3-acc8a04e53ee@amd.com>
To:     "Limonciello, Mario" <Mario.Limonciello@amd.com>
Precedence: bulk


> On 22-Jun-2023, at 8:08 PM, Limonciello, Mario =
<Mario.Limonciello@amd.com> wrote:
>=20
>=20
> On 6/22/2023 7:36 AM, Michael Ellerman wrote:
>> "Linux regression tracking (Thorsten Leemhuis)" =
<regressions@leemhuis.info> writes:
>>> Hi, Thorsten here, the Linux kernel's regression tracker. =
Top-posting
>>> for once, to make this easily accessible to everyone.
>>>=20
>>> As Linus will likely release 6.4 on this or the following Sunday a =
quick
>>> question: is there any hope this regression might be fixed any time
>>> soon?
>> No.
>>=20
>> I have added the author of the commit to Cc, maybe they can help?
>>=20
>> The immediate question is, is it expected for chip->ops to be NULL in
>> this path? Obviously on actual AMD systems that isn't the case,
>> otherwise the code would crash there. But is the fact that chip->ops =
is
>> NULL a bug in the ibmvtpm driver, or a possibility that has been
>> overlooked by the checking code.
>>=20
>> cheers
>=20
> All that code assumes that the TPM is still functional which
> seems not to be the case for your TPM.
>=20
> This should fix it:

Yes, with this change kexec works correctly.

Since Aneesh first reported this problem including reported by credit =
for him

Reported-by: Aneesh Kumar K. V <aneesh.kumar@linux.ibm.com>
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>

-Sachin=