linux-kernel - Re: [PATCH v3] tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm

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Message-ID: <20200319231552.GA25351@us.ibm.com>
Date:   Thu, 19 Mar 2020 18:15:52 -0500
From:   George Wilson <gcwilson@...ux.ibm.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Cc:     linux-integrity@...r.kernel.org,
        Alexey Kardashevskiy <aik@...abs.ru>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>, linux-kernel@...r.kernel.org,
        Linh Pham <phaml@...ibm.com>
Subject: Re: [PATCH v3] tpm: ibmvtpm: retry on H_CLOSED in tpm_ibmvtpm_send()

On Thu, Mar 19, 2020 at 09:55:03PM +0200, Jarkko Sakkinen wrote:
> On Thu, Mar 19, 2020 at 09:50:16PM +0200, Jarkko Sakkinen wrote:
> > On Wed, Mar 18, 2020 at 07:49:27PM -0400, George Wilson wrote:
> > > tpm_ibmvtpm_send() can fail during PowerVM Live Partition Mobility resume
> > > with an H_CLOSED return from ibmvtpm_send_crq().  The PAPR says, 'The
> > > “partner partition suspended” transport event disables the associated CRQ
> > > such that any H_SEND_CRQ hcall() to the associated CRQ returns H_Closed
> > > until the CRQ has been explicitly enabled using the H_ENABLE_CRQ hcall.'
> > > This patch adds a check in tpm_ibmvtpm_send() for an H_CLOSED return from
> > > ibmvtpm_send_crq() and in that case calls tpm_ibmvtpm_resume() and
> > > retries the ibmvtpm_send_crq() once.
> > > 
> > > Reported-by: Linh Pham <phaml@...ibm.com>
> > > Reviewed-by: Stefan Berger <stefanb@...ux.ibm.com>
> > > Signed-off-by: George Wilson <gcwilson@...ux.ibm.com>
> > > Tested-by: Linh Pham <phaml@...ibm.com>
> > > Fixes: 132f76294744 ("Add new device driver to support IBM vTPM")
> > 
> > Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
> 
> Unfortunately have to take that back because it has checkpatch
> errors:
> 
> $ scripts/checkpatch.pl 0001-tpm-ibmvtpm-retry-on-H_CLOSED-in-tpm_ibmvtpm_send.patch
> WARNING: Possible unwrapped commit description (prefer a maximum 75 chars per line)
> #11:
> “partner partition suspended” transport event disables the associated CRQ

I'd noticed that but it appears to be a spurious checkpatch warning.
The line is 73 chars long, the same as the first line of the commit
description.  Maybe the quotes throw it off?

> 
> WARNING: Prefer using '"%s...", __func__' to using 'ibmvtpm_crq_send_init', this function's name, in a string
> #61: FILE: drivers/char/tpm/tpm_ibmvtpm.c:152:
> +			"ibmvtpm_crq_send_init failed rc=%d\n", rc);

I didn't change that error string because it's in an unmodified existing
function that I moved above the caller so a declaration wasn't required.
All other examples in the file are the same.  I'm of course happy to
change it in this function if you think it's appropriate to do so.

> 
> Also the fixes tag is incorrect. Should be:
> 
> Fixes: 132f76294744 ("drivers/char/tpm: Add new device driver to support IBM vTPM")

I see it done different ways, mostly without the path, even for the TPM
drivers.  For example, there's no path in Stefan's "[PATCH v7 2/3] tpm:
ibmvtpm: Wait for buffer to be set before proceeding."  I'm certainly
happy to change it, however, and it's good to know that's the preferred
style going forward.

Separate topic:  Since this fixes a migration hang, do you think it
should also be cc'd to stable?

> 
> /Jarkko

-- 
George Wilson
IBM Linux Technology Center
Security Development