From: Vaibhav Jain <vaibhav@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Oliver O'Halloran <oohall@gmail.com>,
Vaibhav Jain <vaibhav@linux.ibm.com>,
Laurent Dufour <ldufour@linux.vnet.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH 0/2] powerpc/papr_scm: Workaround for failure of drc bind after kexec
Date: Mon, 24 Jun 2019 20:29:11 +0530 [thread overview]
Message-ID: <20190624145913.20122-1-vaibhav@linux.ibm.com> (raw)
Presently an error is returned in response to hcall H_SCM_BIND_MEM when a
new kernel boots on lpar via kexec. This prevents papr_scm from registering
drc memory regions with nvdimm. The error reported is of the form below:
"papr_scm ibm,persistent-memory:ibm,pmemory@44100002: bind err: -68"
On investigation it was revealed that phyp returns this error as previous
kernel did not completely release bindings for drc scm-memory blocks and
hence phyp rejected request for re-binding these block to lpar with error
H_OVERLAP. Also support for a new H_SCM_UNBIND_ALL is recently added which
is better suited for releasing all the bound scm-memory block from an lpar.
So leveraging new hcall H_SCM_UNBIND_ALL, we can workaround H_OVERLAP issue
during kexec by forcing an unbind of all drm scm-memory blocks and issuing
H_SCM_BIND_MEM to re-bind the drc scm-memory blocks to lpar. This sequence
will also be needed when a new kernel boot on lpar after previous kernel
panicked and it never got an opportunity to call H_SCM_UNBIND_MEM/ALL.
Hence this patch-set implements following changes to papr_scm module:
* Update it to use H_SCM_UNBIND_ALL instead of H_SCM_UNBIND_MEM
* In case hcall H_SCM_BIND_MEM fails with error H_OVERLAP, force
H_SCM_UNBIND_ALL and retry the bind operation again.
With the patch-set applied re-bind of drc scm-memory to lpar succeeds after
a kexec to new kernel as illustrated below:
# Old kernel
$ sudo ndctl list -R
[
{
"dev":"region0",
<snip>
....
}
]
# kexec to new kernel
$ sudo kexec --initrd=... vmlinux
...
...
I'm in purgatory
...
papr_scm ibm,persistent-memory:ibm,pmemory@44100002: Un-binding and retrying
...
# New kernel
$ sudo ndctl list -R
$ sudo ndctl list -R
[
{
"dev":"region0",
<snip>
....
}
]
Vaibhav Jain (2):
powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL
powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails
arch/powerpc/include/asm/hvcall.h | 2 +-
arch/powerpc/platforms/pseries/papr_scm.c | 60 ++++++++++++++++++++---
2 files changed, 53 insertions(+), 9 deletions(-)
--
2.21.0
next reply other threads:[~2019-06-24 15:12 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-24 14:59 Vaibhav Jain [this message]
2019-06-24 14:59 ` [PATCH 1/2] powerpc/papr_scm: Update drc_pmem_unbind() to use H_SCM_UNBIND_ALL Vaibhav Jain
2019-06-25 0:58 ` Oliver O'Halloran
2019-06-24 14:59 ` [PATCH 2/2] powerpc/papr_scm: Force a scm-unbind if initial scm-bind fails Vaibhav Jain
2019-06-25 1:23 ` Oliver O'Halloran
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