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powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails

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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>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190629160610.23402-4-vaibhav@linux.ibm.com
This commit is contained in:
Vaibhav Jain 2019-06-29 21:36:10 +05:30 committed by Michael Ellerman
parent 0d7fc080ba
commit 3a855b7ac7
1 changed files with 14 additions and 1 deletions
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15
arch/powerpc/platforms/pseries/papr_scm.c
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@ -44,8 +44,9 @@ 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
@ -65,6 +66,10 @@ 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;
}
@ -404,6 +409,14 @@ 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);
rc = drc_pmem_bind(p);
}
if (rc)
goto err;