MAINTAINERS | 4 + drivers/pci/Kconfig | 10 + drivers/pci/Makefile | 2 + drivers/pci/liveupdate.c | 450 +++++++++++++++++++++++++++++++++++++++++ drivers/pci/pci-lu-stub.c | 140 +++++++++++++ drivers/pci/pci.c | 7 +- drivers/pci/pci.h | 8 + drivers/pci/pcie/portdrv.c | 13 ++ drivers/pci/probe.c | 8 +- include/linux/dev_liveupdate.h | 69 +++++++ include/linux/device.h | 15 ++ include/linux/device/driver.h | 6 + include/linux/pci.h | 9 + 13 files changed, 738 insertions(+), 3 deletions(-)
This is phase I of the LUO PCI series. It does the minimal set of PCI
device liveupdate which is preserving a bus master bit in the PCI command
register.
The LUO PCI subsystem is based on the LUO V2 series.
https://lore.kernel.org/lkml/20250515182322.117840-1-pasha.tatashin@soleen.com/
It registers the PCI as a LUO subsystem and forwards the liveupdate
callback to the device. The struct dev_liveupdate has been add to struct
device to keep track of the liveupdate related context.
A device can be marked as requested for liveupdate during the normal
state.
In the prepare() callback. The PCI core will build a list of the PCI device
for liveupdate based on the PCI device dependency:
1) The requested device is dependent on the PCI bridge it is on to preserve
the bridge bus master. All the way to the root bridge. If the bus master
has been disabled on the bridge, the DMA on the children devices will
get impacted.
The list of liveupdate devices is used for prepare(), cancel(), freeze()
and finalized() callback.
The PCI subsystem will preserve the driver name for each liveupdate PCI
device and only probe that driver after kexec boot up.
Disclaimer:
The data preservation format is not final. It currently uses C struct
directly. It does not deal with version change on the data format yet. I
do have some idea how to address the versioning of data layout. Those
will be outside the scope of this series.
Testing:
Testing was done with Intel diorite NVMe VF device 8086:1457. Bind the
test device with pci-lu-stub driver.
0000:05:00.1 current driver is
0000:05:00.1 bind new driver pci-lu-stub
[ 557.006998] pci-lu-stub 0000:05:00.1: Marking device liveupdate busmaster
Now perform luo prepare, the PCI subsystem builds the liveupdate device
list from the PCI root bridge. The test device will have LU_BUSMASTER
and the PCI bridge will have LU_BUSMASTER_BRIDGE.
[ 701.573423] pci-lu-stub 0000:05:00.1: PCI liveupdate: collect liveupdate device: flags 1
[ 701.582430] pcieport 0000:04:01.0: PCI liveupdate: collect liveupdate device: flags 2
[ 701.590297] pci-lu-stub 0000:05:00.1: pci_lu_stub_prepare(): data: 0x1ac6f4000
[ 701.598916] PCI liveupdate: prepare data[1f1d28000]
[ 701.603832] luo_core: Switched from [normal] to [prepared] state
After kexec reboot. The liveupdate devices are probed and restores the live
update context.
[ 3.622083] pci 0000:04:01.0: PCI liveupdate: liveupdate restore flags 2 driver: pcieport data: [0]
[ 4.768060] pci 0000:05:00.1: PCI liveupdate: liveupdate restore flags 1 driver: pci-lu-stub data: [1ac6f4000]
Perform luo finish to convert from update state to normal state. The
reserved folio will be freed.
[ 310.359830] PCI liveupdate: finish data[1f1d28000]
[ 310.364664] pci-lu-stub 0000:05:00.1: pci_lu_stub_finish(): data: 0x1ac6f4000
[ 310.371824] luo_core: Switched from [updated] to [normal] state
Signed-off-by: Chris Li <chrisl@kernel.org>
---
Changes in v2:
- reduce the scope of the series to phase I. Only preserve the bus
master bit.
- Use finer grain flags to specify which liveupdate feature gets
preserved.
- Modify the pci-lu-stub driver to set the bus master bit before
requesting preserving the bus master.
- Add WARN_ON() for the PCI device has LU_BUSMASTER but the bus master
bit is not set.
- Link to v1: https://lore.kernel.org/r/20250728-luo-pci-v1-0-955b078dd653@kernel.org
---
Chris Li (10):
PCI/LUO: Register with Liveupdate Orchestrator
PCI/LUO: Create requested liveupdate device list
PCI/LUO: Forward prepare()/freeze()/cancel() callbacks to driver
PCI/LUO: Restore state at PCI enumeration
PCI/LUO: Forward finish callbacks to drivers
PCI/LUO: Save and restore driver name
PCI/LUO: Add liveupdate to pcieport driver
PCI/LUO: Add pci_liveupdate_get_driver_data()
PCI/LUO: Avoid write to bus master at boot
PCI: pci-lu-stub: Add a stub driver for Live Update testing
MAINTAINERS | 4 +
drivers/pci/Kconfig | 10 +
drivers/pci/Makefile | 2 +
drivers/pci/liveupdate.c | 450 +++++++++++++++++++++++++++++++++++++++++
drivers/pci/pci-lu-stub.c | 140 +++++++++++++
drivers/pci/pci.c | 7 +-
drivers/pci/pci.h | 8 +
drivers/pci/pcie/portdrv.c | 13 ++
drivers/pci/probe.c | 8 +-
include/linux/dev_liveupdate.h | 69 +++++++
include/linux/device.h | 15 ++
include/linux/device/driver.h | 6 +
include/linux/pci.h | 9 +
13 files changed, 738 insertions(+), 3 deletions(-)
---
base-commit: 9ab803064e3d1be9673d2829785a69fd0578b24e
change-id: 20250724-luo-pci-1291890b710f
Best regards,
--
Chris Li <chrisl@kernel.org>
On Tue, Sep 16, 2025 at 12:45:08AM -0700, Chris Li wrote:
> This is phase I of the LUO PCI series. It does the minimal set of PCI
> device liveupdate which is preserving a bus master bit in the PCI command
> register.
>
> The LUO PCI subsystem is based on the LUO V2 series.
> https://lore.kernel.org/lkml/20250515182322.117840-1-pasha.tatashin@soleen.com/
Pasha's email points to
https://github.com/googleprodkernel/linux-liveupdate/tree/luo/rfc-v2,
so I cloned https://github.com/googleprodkernel/linux-liveupdate.git
and tried to apply this series on top of the luo/rfc-v2 branch (head
5c8d261fdc15 ("MAINTAINERS: add liveupdate entry")), but it doesn't
apply cleanly.
Also tried the luo/v2 branch (head 75716df00a94 ("libluo: add
tests")), but it doesn't apply there either.
Am I looking the wrong place? Do you have a public repo with this
series in it?
Bjorn
Hi Bjorn,
My latest submission is the following:
https://lore.kernel.org/all/20250807014442.3829950-1-pasha.tatashin@soleen.com/
And github repo is in cover letter:
https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v3
It applies cleanly against the mainline without the first three
patches, as they were already merged.
Pasha
On Sat, Sep 27, 2025 at 1:13 PM Bjorn Helgaas <helgaas@kernel.org> wrote:
>
> On Tue, Sep 16, 2025 at 12:45:08AM -0700, Chris Li wrote:
> > This is phase I of the LUO PCI series. It does the minimal set of PCI
> > device liveupdate which is preserving a bus master bit in the PCI command
> > register.
> >
> > The LUO PCI subsystem is based on the LUO V2 series.
> > https://lore.kernel.org/lkml/20250515182322.117840-1-pasha.tatashin@soleen.com/
>
> Pasha's email points to
> https://github.com/googleprodkernel/linux-liveupdate/tree/luo/rfc-v2,
> so I cloned https://github.com/googleprodkernel/linux-liveupdate.git
> and tried to apply this series on top of the luo/rfc-v2 branch (head
> 5c8d261fdc15 ("MAINTAINERS: add liveupdate entry")), but it doesn't
> apply cleanly.
>
> Also tried the luo/v2 branch (head 75716df00a94 ("libluo: add
> tests")), but it doesn't apply there either.
>
> Am I looking the wrong place? Do you have a public repo with this
> series in it?
>
> Bjorn
On Sat, Sep 27, 2025 at 02:05:38PM -0400, Pasha Tatashin wrote:
> Hi Bjorn,
>
> My latest submission is the following:
> https://lore.kernel.org/all/20250807014442.3829950-1-pasha.tatashin@soleen.com/
>
> And github repo is in cover letter:
>
> https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v3
>
> It applies cleanly against the mainline without the first three
> patches, as they were already merged.
Not sure what I'm missing. I've tried various things but none apply
cleanly:
$ git remote add luo https://github.com/googleprodkernel/linux-liveupdate.git
$ git fetch luo
From https://github.com/googleprodkernel/linux-liveupdate
* [new branch] hack_pci_pf_stub_demo -> luo/hack_pci_pf_stub_demo
* [new branch] iommu/rfc-v1 -> luo/iommu/rfc-v1
* [new branch] kho/v5 -> luo/kho/v5
* [new branch] kho/v6 -> luo/kho/v6
* [new branch] kho/v7 -> luo/kho/v7
* [new branch] kho/v8 -> luo/kho/v8
* [new branch] lucx/v1 -> luo/lucx/v1
* [new branch] luo/kho-v8 -> luo/luo/kho-v8
* [new branch] luo/memfd-v0.1 -> luo/luo/memfd-v0.1
* [new branch] luo/rfc-v1 -> luo/luo/rfc-v1
* [new branch] luo/rfc-v2 -> luo/luo/rfc-v2
* [new branch] luo/v1 -> luo/luo/v1
* [new branch] luo/v2 -> luo/luo/v2
* [new branch] luo/v3 -> luo/luo/v3
* [new branch] luo/v4 -> luo/luo/v4
* [new branch] master -> luo/master
$ b4 am -om/ https://lore.kernel.org/r/20250916-luo-pci-v2-0-c494053c3c08@kernel.org
Grabbing thread from lore.kernel.org/all/20250916-luo-pci-v2-0-c494053c3c08@kernel.org/t.mbox.gz
Analyzing 13 messages in the thread
Looking for additional code-review trailers on lore.kernel.org
Checking attestation on all messages, may take a moment...
---
✓ [PATCH v2 1/10] PCI/LUO: Register with Liveupdate Orchestrator
✓ [PATCH v2 2/10] PCI/LUO: Create requested liveupdate device list
✓ [PATCH v2 3/10] PCI/LUO: Forward prepare()/freeze()/cancel() callbacks to driver
✓ [PATCH v2 4/10] PCI/LUO: Restore state at PCI enumeration
✓ [PATCH v2 5/10] PCI/LUO: Forward finish callbacks to drivers
✓ [PATCH v2 6/10] PCI/LUO: Save and restore driver name
✓ [PATCH v2 7/10] PCI/LUO: Add liveupdate to pcieport driver
✓ [PATCH v2 8/10] PCI/LUO: Add pci_liveupdate_get_driver_data()
✓ [PATCH v2 9/10] PCI/LUO: Avoid write to bus master at boot
✓ [PATCH v2 10/10] PCI: pci-lu-stub: Add a stub driver for Live Update testing
---
✓ Signed: DKIM/kernel.org
---
Total patches: 10
---
Cover: m/v2_20250916_chrisl_luo_pci_subsystem_phase_i.cover
Link: https://lore.kernel.org/r/20250916-luo-pci-v2-0-c494053c3c08@kernel.org
Base: base-commit 9ab803064e3d1be9673d2829785a69fd0578b24e not known, ignoring
Base: not specified
git am m/v2_20250916_chrisl_luo_pci_subsystem_phase_i.mbx
$ git checkout -b wip/2509-chris-luo-pci-v2 luo/luo/rfc-v2; git am m/v2_20250916_chrisl_luo_pci_subsystem_phase_i.mbx
Updating files: 100% (21294/21294), done.
branch 'wip/2509-chris-luo-pci-v2' set up to track 'luo/luo/rfc-v2'.
Switched to a new branch 'wip/2509-chris-luo-pci-v2'
Applying: PCI/LUO: Register with Liveupdate Orchestrator
Applying: PCI/LUO: Create requested liveupdate device list
Applying: PCI/LUO: Forward prepare()/freeze()/cancel() callbacks to driver
Applying: PCI/LUO: Restore state at PCI enumeration
Applying: PCI/LUO: Forward finish callbacks to drivers
Applying: PCI/LUO: Save and restore driver name
error: patch failed: drivers/pci/probe.c:2714
error: drivers/pci/probe.c: patch does not apply
Patch failed at 0006 PCI/LUO: Save and restore driver name
hint: Use 'git am --show-current-patch=diff' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
$ git checkout -b wip/2509-chris-luo-pci-v2 luo/luo/v2; git am m/v2_20250916_chrisl_luo_pci_subsystem_phase_i.mbx
Updating files: 100% (12217/12217), done.
branch 'wip/2509-chris-luo-pci-v2' set up to track 'luo/luo/v2'.
Switched to a new branch 'wip/2509-chris-luo-pci-v2'
Applying: PCI/LUO: Register with Liveupdate Orchestrator
error: patch failed: MAINTAINERS:14014
error: MAINTAINERS: patch does not apply
Patch failed at 0001 PCI/LUO: Register with Liveupdate Orchestrator
hint: Use 'git am --show-current-patch=diff' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
$ git checkout -b wip/2509-chris-luo-pci-v2 luo/luo/v3; git am m/v2_20250916_chrisl_luo_pci_subsystem_phase_i.mbx
branch 'wip/2509-chris-luo-pci-v2' set up to track 'luo/luo/v3'.
Switched to a new branch 'wip/2509-chris-luo-pci-v2'
Applying: PCI/LUO: Register with Liveupdate Orchestrator
error: patch failed: MAINTAINERS:14014
error: MAINTAINERS: patch does not apply
Patch failed at 0001 PCI/LUO: Register with Liveupdate Orchestrator
hint: Use 'git am --show-current-patch=diff' to see the failed patch
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".
On Mon, Sep 29, 2025 at 8:04 AM Bjorn Helgaas <helgaas@kernel.org> wrote: > > On Sat, Sep 27, 2025 at 02:05:38PM -0400, Pasha Tatashin wrote: > > Hi Bjorn, > > > > My latest submission is the following: > > https://lore.kernel.org/all/20250807014442.3829950-1-pasha.tatashin@soleen.com/ > > > > And github repo is in cover letter: > > > > https://github.com/googleprodkernel/linux-liveupdate/tree/luo/v3 > > > > It applies cleanly against the mainline without the first three > > patches, as they were already merged. > > Not sure what I'm missing. I've tried various things but none apply > cleanly: Sorry about that. Let me do a refresh of the LUOPCI V3 patch and send out the git repo link as well. The issue is that there are other patches not in the mainline kernel which luopci is dependent on. Using a git repo would be easier to get a working tree. Working on it now, please stay tuned. Chris
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