arch/powerpc/platforms/pseries/cmm.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
Two smaller fixes identified while doing a bigger rework.
Compile-tested only as I don't have an easy way to test right now.
I would prefer for these patches to go through the MM tree as I will
be sending out a bigger version soon that is based on this series --
I split of the fixes from the other stuff.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
David Hildenbrand (2):
powerpc/pseries/cmm: call balloon_devinfo_init() also without
CONFIG_BALLOON_COMPACTION
powerpc/pseries/cmm: adjust BALLOON_MIGRATE when migrating pages
arch/powerpc/platforms/pseries/cmm.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
base-commit: 8841ba63f874d5dc05fc4beb47788406be96fd5c
--
2.51.0
On 10/21/25 12:06, David Hildenbrand wrote: > Two smaller fixes identified while doing a bigger rework. > > Compile-tested only as I don't have an easy way to test right now. > > I would prefer for these patches to go through the MM tree as I will > be sending out a bigger version soon that is based on this series -- > I split of the fixes from the other stuff. > Ping, I tried to get CMM running again (using the simulation mode I introduced a while back), but so far my attempts to get a reasonable powernv VM booted in QEMU failed :( (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based on a 5.10 kernel without some mystical XFS feature ...) -- Cheers David
"David Hildenbrand (Red Hat)" <david@kernel.org> writes: > On 10/21/25 12:06, David Hildenbrand wrote: >> Two smaller fixes identified while doing a bigger rework. >> >> Compile-tested only as I don't have an easy way to test right now. >> >> I would prefer for these patches to go through the MM tree as I will >> be sending out a bigger version soon that is based on this series -- >> I split of the fixes from the other stuff. >> > > Ping, > > I tried to get CMM running again (using the simulation mode I introduced > a while back), but so far my attempts to get a reasonable powernv VM > booted in QEMU failed :( > > (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based > on a 5.10 kernel without some mystical XFS feature ...) > Sorry, I missed seeing this earlier. Do you have the link to simulation mode which you are referring above please? So far I didn't find the support of this beyond Linux LPAR (pseries), but maybe I missed it. -ritesh
On 11/28/25 06:05, Ritesh Harjani (IBM) wrote:
> "David Hildenbrand (Red Hat)" <david@kernel.org> writes:
>
>> On 10/21/25 12:06, David Hildenbrand wrote:
>>> Two smaller fixes identified while doing a bigger rework.
>>>
>>> Compile-tested only as I don't have an easy way to test right now.
>>>
>>> I would prefer for these patches to go through the MM tree as I will
>>> be sending out a bigger version soon that is based on this series --
>>> I split of the fixes from the other stuff.
>>>
>>
>> Ping,
>>
>> I tried to get CMM running again (using the simulation mode I introduced
>> a while back), but so far my attempts to get a reasonable powernv VM
>> booted in QEMU failed :(
>>
>> (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based
>> on a 5.10 kernel without some mystical XFS feature ...)
>>
>
Hi Ritesh,
> Sorry, I missed seeing this earlier.
>
> Do you have the link to simulation mode which you are referring above
> please? So far I didn't find the support of this beyond Linux LPAR
> (pseries), but maybe I missed it.
When I did a rework of the CMM balloon in 2019, I needed a way to test
it. So I added
commit b1713975c31ae20ecc40fd00191ee3fa51445d4a
Author: David Hildenbrand <david@kernel.org>
Date: Thu Oct 31 15:29:31 2019 +0100
powerpc/pseries/cmm: Simulation mode
Let's allow to test the implementation without needing HW support.
When "simulate=1" is specified when loading the module, we bypass all
HW checks and HW calls. The sysfs file "simulate_loan_target_kb" can
be used to simulate HW requests.
The simualtion mode can be activated using:
modprobe cmm debug=1 simulate=1
And the requested loan target can be changed using:
echo X > /sys/devices/system/cmm/cmm0/simulate_loan_target_kb
I allows for bypassing the absence of FW_FEATURE_CMO.
Back in the days I was able to test it with a pseries (or was it powernv?)
machine we had here at RH. So far my attempts failed to test it in a
similar fashion in QEMU.
--
Cheers
David
"David Hildenbrand (Red Hat)" <david@kernel.org> writes: > On 11/28/25 06:05, Ritesh Harjani (IBM) wrote: >> "David Hildenbrand (Red Hat)" <david@kernel.org> writes: >> >>> On 10/21/25 12:06, David Hildenbrand wrote: >>>> Two smaller fixes identified while doing a bigger rework. >>>> >>>> Compile-tested only as I don't have an easy way to test right now. >>>> >>>> I would prefer for these patches to go through the MM tree as I will >>>> be sending out a bigger version soon that is based on this series -- >>>> I split of the fixes from the other stuff. >>>> >>> >>> Ping, >>> >>> I tried to get CMM running again (using the simulation mode I introduced >>> a while back), but so far my attempts to get a reasonable powernv VM >>> booted in QEMU failed :( >>> >>> (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based >>> on a 5.10 kernel without some mystical XFS feature ...) >>> >> > > Hi Ritesh, > >> Sorry, I missed seeing this earlier. >> >> Do you have the link to simulation mode which you are referring above >> please? So far I didn't find the support of this beyond Linux LPAR >> (pseries), but maybe I missed it. > > When I did a rework of the CMM balloon in 2019, I needed a way to test > it. So I added > > commit b1713975c31ae20ecc40fd00191ee3fa51445d4a > Author: David Hildenbrand <david@kernel.org> > Date: Thu Oct 31 15:29:31 2019 +0100 > > powerpc/pseries/cmm: Simulation mode aah right. I should have looked closely. I was thinking you meant somewhere in Qemu, so I was only looking there. > > Let's allow to test the implementation without needing HW support. > When "simulate=1" is specified when loading the module, we bypass all > HW checks and HW calls. The sysfs file "simulate_loan_target_kb" can > be used to simulate HW requests. > > The simualtion mode can be activated using: > modprobe cmm debug=1 simulate=1 > > And the requested loan target can be changed using: > echo X > /sys/devices/system/cmm/cmm0/simulate_loan_target_kb > > > I allows for bypassing the absence of FW_FEATURE_CMO. > Right. Let me give it a try first with pseries Qemu. Otherwise I have an access to pseries LPAR too. I can verify it there. > Back in the days I was able to test it with a pseries (or was it powernv?) Agree the name can be a bit confusing. So powernv == Power Non-Virtualized that's the baremetal Power box. pseries == is basically the Linux LPAR on PowerVM. Qemu/KVM also has support for booting Linux pseries guest. > machine we had here at RH. So far my attempts failed to test it in a > similar fashion in QEMU. > Let me give it a try and I will update how it goes. Thanks! -ritesh
On 11/28/25 08:49, Ritesh Harjani (IBM) wrote: > "David Hildenbrand (Red Hat)" <david@kernel.org> writes: > >> On 11/28/25 06:05, Ritesh Harjani (IBM) wrote: >>> "David Hildenbrand (Red Hat)" <david@kernel.org> writes: >>> >>>> On 10/21/25 12:06, David Hildenbrand wrote: >>>>> Two smaller fixes identified while doing a bigger rework. >>>>> >>>>> Compile-tested only as I don't have an easy way to test right now. >>>>> >>>>> I would prefer for these patches to go through the MM tree as I will >>>>> be sending out a bigger version soon that is based on this series -- >>>>> I split of the fixes from the other stuff. >>>>> >>>> >>>> Ping, >>>> >>>> I tried to get CMM running again (using the simulation mode I introduced >>>> a while back), but so far my attempts to get a reasonable powernv VM >>>> booted in QEMU failed :( >>>> >>>> (e.g., Fedora qcow2 images use xfs, but the open powernv loader is based >>>> on a 5.10 kernel without some mystical XFS feature ...) >>>> >>> >> >> Hi Ritesh, >> >>> Sorry, I missed seeing this earlier. >>> >>> Do you have the link to simulation mode which you are referring above >>> please? So far I didn't find the support of this beyond Linux LPAR >>> (pseries), but maybe I missed it. >> >> When I did a rework of the CMM balloon in 2019, I needed a way to test >> it. So I added >> >> commit b1713975c31ae20ecc40fd00191ee3fa51445d4a >> Author: David Hildenbrand <david@kernel.org> >> Date: Thu Oct 31 15:29:31 2019 +0100 >> >> powerpc/pseries/cmm: Simulation mode > > aah right. I should have looked closely. I was thinking you meant > somewhere in Qemu, so I was only looking there. > >> >> Let's allow to test the implementation without needing HW support. >> When "simulate=1" is specified when loading the module, we bypass all >> HW checks and HW calls. The sysfs file "simulate_loan_target_kb" can >> be used to simulate HW requests. >> >> The simualtion mode can be activated using: >> modprobe cmm debug=1 simulate=1 >> >> And the requested loan target can be changed using: >> echo X > /sys/devices/system/cmm/cmm0/simulate_loan_target_kb >> >> >> I allows for bypassing the absence of FW_FEATURE_CMO. >> > > Right. Let me give it a try first with pseries Qemu. Otherwise I have an > access to pseries LPAR too. I can verify it there. Ah, now I realize my problem: I tried with Fedora 43 in a powerpc VM but the modprobe didn't do anything. Looking again: # grep CONFIG_CMM /boot/config-6.17.1-300.fc43.ppc64le CONFIG_CMM=y So modprob'ing won't do as the module is built in. Anyhow, compiling a kernel inside a QEMU VM might take a while, so if you can beat me to it I wouldn't be mad :) Re powernv vs. powerpc: yeah, it's confusing. For some reason I thought I tested it in the days on powernv. Maybe that's simply because I was only able to get my hands on such a machine. Looking again, it should indeed be able to be simulated on a simple powerpc VM. -- Cheers David
>> >> Right. Let me give it a try first with pseries Qemu. Otherwise I have an >> access to pseries LPAR too. I can verify it there. > > Ah, now I realize my problem: I tried with Fedora 43 in a powerpc VM but > the modprobe didn't do anything. > > Looking again: > > # grep CONFIG_CMM /boot/config-6.17.1-300.fc43.ppc64le > CONFIG_CMM=y > > So modprob'ing won't do as the module is built in. Right, so doing "cmm.simulate=1" on the cmdline in a Fedora 43 VMs properly creates the CMM device. -- Cheers David
"David Hildenbrand (Red Hat)" <david@kernel.org> writes: >>> >>> Right. Let me give it a try first with pseries Qemu. Otherwise I have an >>> access to pseries LPAR too. I can verify it there. >> >> Ah, now I realize my problem: I tried with Fedora 43 in a powerpc VM but >> the modprobe didn't do anything. >> >> Looking again: >> >> # grep CONFIG_CMM /boot/config-6.17.1-300.fc43.ppc64le >> CONFIG_CMM=y >> >> So modprob'ing won't do as the module is built in. > > Right, so doing "cmm.simulate=1" on the cmdline in a Fedora 43 VMs > properly creates the CMM device. > Right verifying using simulate mode is very straightforward. Thanks for that! So.. using various random echo X > simulate_loan_target_kb on a VM... ~# cat /proc/vmstat |grep balloon nr_balloon_pages 16 balloon_inflate 1638 balloon_deflate 1622 balloon_migrate 4 -ritesh
On 11/28/25 11:40, Ritesh Harjani (IBM) wrote: > "David Hildenbrand (Red Hat)" <david@kernel.org> writes: > >>>> >>>> Right. Let me give it a try first with pseries Qemu. Otherwise I have an >>>> access to pseries LPAR too. I can verify it there. >>> >>> Ah, now I realize my problem: I tried with Fedora 43 in a powerpc VM but >>> the modprobe didn't do anything. >>> >>> Looking again: >>> >>> # grep CONFIG_CMM /boot/config-6.17.1-300.fc43.ppc64le >>> CONFIG_CMM=y >>> >>> So modprob'ing won't do as the module is built in. >> >> Right, so doing "cmm.simulate=1" on the cmdline in a Fedora 43 VMs >> properly creates the CMM device. >> > > Right verifying using simulate mode is very straightforward. Thanks for that! > So.. using various random echo X > simulate_loan_target_kb on a VM... > > ~# cat /proc/vmstat |grep balloon > nr_balloon_pages 16 > balloon_inflate 1638 > balloon_deflate 1622 > balloon_migrate 4 Thanks a bunch for the review and testing! -- Cheers David
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