From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
To: Vaibhav Jain <vaibhav@linux.ibm.com>, linuxppc-dev@lists.ozlabs.org
Cc: Laurent Dufour <ldufour@linux.vnet.ibm.com>,
Vaibhav Jain <vaibhav@linux.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>,
Oliver O'Halloran <oohall@gmail.com>
Subject: Re: [PATCH v3 3/3] powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails
Date: Wed, 26 Jun 2019 22:28:43 +0530 [thread overview]
Message-ID: <87k1d8z3jw.fsf@linux.ibm.com> (raw)
In-Reply-To: <20190626140404.27448-4-vaibhav@linux.ibm.com>
Vaibhav Jain <vaibhav@linux.ibm.com> writes:
> In some cases initial bind of scm memory for an lpar can fail if
> previously it wasn't released using a scm-unbind hcall. This situation
> can arise due to panic of the previous kernel or forced lpar
> fadump. In such cases the H_SCM_BIND_MEM return a H_OVERLAP error.
>
> To mitigate such cases the patch updates papr_scm_probe() to force a
> call to drc_pmem_unbind() in case the initial bind of scm memory fails
> with EBUSY error. In case scm-bind operation again fails after the
> forced scm-unbind then we follow the existing error path. We also
> update drc_pmem_bind() to handle the H_OVERLAP error returned by phyp
> and indicate it as a EBUSY error back to the caller.
>
> Suggested-by: "Oliver O'Halloran" <oohall@gmail.com>
> Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
> ---
> Change-log:
> v3:
> * Minor update to a code comment. [Oliver]
>
> v2:
> * Moved the retry code from drc_pmem_bind() to papr_scm_probe()
> [Oliver]
> * Changed the type of variable 'rc' in drc_pmem_bind() to
> int64_t. [Oliver]
> ---
> arch/powerpc/platforms/pseries/papr_scm.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/platforms/pseries/papr_scm.c b/arch/powerpc/platforms/pseries/papr_scm.c
> index c01a03fd3ee7..7c5e10c063a0 100644
> --- a/arch/powerpc/platforms/pseries/papr_scm.c
> +++ b/arch/powerpc/platforms/pseries/papr_scm.c
> @@ -43,8 +43,9 @@ struct papr_scm_priv {
> static int drc_pmem_bind(struct papr_scm_priv *p)
> {
> unsigned long ret[PLPAR_HCALL_BUFSIZE];
> - uint64_t rc, token;
> uint64_t saved = 0;
> + uint64_t token;
> + int64_t rc;
>
> /*
> * When the hypervisor cannot map all the requested memory in a single
> @@ -64,6 +65,10 @@ static int drc_pmem_bind(struct papr_scm_priv *p)
> } while (rc == H_BUSY);
>
> if (rc) {
> + /* H_OVERLAP needs a separate error path */
> + if (rc == H_OVERLAP)
> + return -EBUSY;
> +
> dev_err(&p->pdev->dev, "bind err: %lld\n", rc);
> return -ENXIO;
> }
> @@ -331,6 +336,14 @@ static int papr_scm_probe(struct platform_device *pdev)
>
> /* request the hypervisor to bind this region to somewhere in memory */
> rc = drc_pmem_bind(p);
> +
> + /* If phyp says drc memory still bound then force unbound and retry */
> + if (rc == -EBUSY) {
> + dev_warn(&pdev->dev, "Retrying bind after unbinding\n");
> + drc_pmem_unbind(p);
This should only be caused by kexec right? And considering kernel nor
hypervisor won't change device binding details, can you check switching
this to H_SCM_QUERY_BLOCK_MEM_BINDING? Will that result in faster boot?
> + rc = drc_pmem_bind(p);
> + }
> +
> if (rc)
> goto err;
>
I am also not sure about the module reference count here. Should we
increment the module reference count after a bind so that we can track
failures in ubind and fail the module unload?
-aneesh
next prev parent reply other threads:[~2019-06-26 17:00 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 14:04 [PATCH v3 0/3] powerpc/papr_scm: Workaround for failure of drc bind after kexec Vaibhav Jain
2019-06-26 14:04 ` [PATCH v3 1/3] powerpc/pseries: Update SCM hcall op-codes in hvcall.h Vaibhav Jain
2019-06-26 16:53 ` Aneesh Kumar K.V
2019-06-27 1:10 ` Oliver O'Halloran
2019-06-28 3:39 ` Michael Ellerman
2019-06-28 4:36 ` Oliver O'Halloran
2019-06-29 11:30 ` Michael Ellerman
2019-06-29 16:09 ` Vaibhav Jain
2019-06-26 14:04 ` [PATCH v3 2/3] powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL Vaibhav Jain
2019-06-26 15:41 ` Aneesh Kumar K.V
2019-06-27 14:40 ` Vaibhav Jain
2019-06-26 14:04 ` [PATCH v3 3/3] powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails Vaibhav Jain
2019-06-26 16:58 ` Aneesh Kumar K.V [this message]
2019-06-27 1:41 ` Oliver O'Halloran
2019-06-27 2:56 ` Aneesh Kumar K.V
2019-06-27 3:39 ` Oliver O'Halloran
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