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[v7,0/5] Fix DPC hotplug race and enhance error handling

Message ID 20201003075514.32935-1-haifeng.zhao@intel.com (mailing list archive)
Headers show
Series Fix DPC hotplug race and enhance error handling | expand

Message

Zhao, Haifeng Oct. 3, 2020, 7:55 a.m. UTC 
Hi,folks,

This simple patch set fixed some serious security issues found when DPC
error injection and NVMe SSD hotplug brute force test were doing -- race
condition between DPC handler and pciehp, AER interrupt handlers, caused
system hang and system with DPC feature couldn't recover to normal
working state as expected (NVMe instance lost, mount operation hang,
race PCIe access caused uncorrectable errors reported alternatively etc).

With this patch set applied, stable 5.9-rc6 on ICS (Ice Lake SP platform,
see
https://en.wikichip.org/wiki/intel/microarchitectures/ice_lake_(server))

could pass the PCIe Gen4 NVMe SSD brute force hotplug test with any time
interval between hot-remove and plug-in operation tens of times without
any errors occur and system works normal.

With this patch set applied, system with DPC feature could recover from
NON-FATAL and FATAL errors injection test and works as expected.

System works smoothly when errors happen while hotplug is doing, no
uncorrectable errors found.

Brute DPC error injection script:

for i in {0..100}
do
        setpci -s 64:02.0 0x196.w=000a
        setpci -s 65:00.0 0x04.w=0544
        mount /dev/nvme0n1p1 /root/nvme
        sleep 1
done

Other details see every commits description part.

This patch set could be applied to stable 5.9-rc6/rc7 directly.

Help to review and test.

v2: changed according to review by Andy Shevchenko.
v3: changed patch 4/5 to simpler coding.
v4: move function pci_wait_port_outdpc() to DPC driver and its
   declaration to pci.h. (tip from Christoph Hellwig <hch@infradead.org>).
v5: fix building issue reported by lkp@intel.com with some config.
v6: move patch[3/5] as the first patch according to Lukas's suggestion.
    and rewrite the comment part of patch[3/5].
v7: change the patch[4/5], based on Bjorn's code and truth table.
    change the patch[5/5] about the debug output information.

Thanks,
Ethan 


Ethan Zhao (5):
  PCI/ERR: get device before call device driver to avoid NULL pointer
    dereference
  PCI/DPC: define a function to check and wait till port finish DPC
    handling
  PCI: pciehp: check and wait port status out of DPC before handling
    DLLSC and PDC
  PCI: only return true when dev io state is really changed
  PCI/ERR: don't mix io state not changed and no driver together

 drivers/pci/hotplug/pciehp_hpc.c |  4 ++-
 drivers/pci/pci.h                | 55 +++++++++++++-------------------
 drivers/pci/pcie/dpc.c           | 27 ++++++++++++++++
 drivers/pci/pcie/err.c           | 18 +++++++++--
 4 files changed, 68 insertions(+), 36 deletions(-)


base-commit: a1b8638ba1320e6684aa98233c15255eb803fac7

Comments

Raj, Ashok Oct. 4, 2020, 4:57 a.m. UTC | #1 
Hi Ethan

On Sat, Oct 03, 2020 at 03:55:09AM -0400, Ethan Zhao wrote:
> Hi,folks,
> 
> This simple patch set fixed some serious security issues found when DPC
> error injection and NVMe SSD hotplug brute force test were doing -- race
> condition between DPC handler and pciehp, AER interrupt handlers, caused
> system hang and system with DPC feature couldn't recover to normal
> working state as expected (NVMe instance lost, mount operation hang,
> race PCIe access caused uncorrectable errors reported alternatively etc).

I think maybe picking from other commit messages to make this description in 
cover letter bit clear. The fundamental premise is that when due to error
conditions when events are processed by both DPC handler and hotplug handling of 
DLLSC both operating on the same device object ends up with crashes.


> 
> With this patch set applied, stable 5.9-rc6 on ICS (Ice Lake SP platform,
> see
> https://en.wikichip.org/wiki/intel/microarchitectures/ice_lake_(server))
> 
> could pass the PCIe Gen4 NVMe SSD brute force hotplug test with any time
> interval between hot-remove and plug-in operation tens of times without
> any errors occur and system works normal.

> 
> With this patch set applied, system with DPC feature could recover from
> NON-FATAL and FATAL errors injection test and works as expected.
> 
> System works smoothly when errors happen while hotplug is doing, no
> uncorrectable errors found.
> 
> Brute DPC error injection script:
> 
> for i in {0..100}
> do
>         setpci -s 64:02.0 0x196.w=000a
>         setpci -s 65:00.0 0x04.w=0544
>         mount /dev/nvme0n1p1 /root/nvme
>         sleep 1
> done
> 
> Other details see every commits description part.
> 
> This patch set could be applied to stable 5.9-rc6/rc7 directly.
> 
> Help to review and test.
> 
> v2: changed according to review by Andy Shevchenko.
> v3: changed patch 4/5 to simpler coding.
> v4: move function pci_wait_port_outdpc() to DPC driver and its
>    declaration to pci.h. (tip from Christoph Hellwig <hch@infradead.org>).
> v5: fix building issue reported by lkp@intel.com with some config.
> v6: move patch[3/5] as the first patch according to Lukas's suggestion.
>     and rewrite the comment part of patch[3/5].
> v7: change the patch[4/5], based on Bjorn's code and truth table.
>     change the patch[5/5] about the debug output information.
> 
> Thanks,
> Ethan 
> 
> 
> Ethan Zhao (5):
>   PCI/ERR: get device before call device driver to avoid NULL pointer
>     dereference
>   PCI/DPC: define a function to check and wait till port finish DPC
>     handling
>   PCI: pciehp: check and wait port status out of DPC before handling
>     DLLSC and PDC
>   PCI: only return true when dev io state is really changed
>   PCI/ERR: don't mix io state not changed and no driver together
> 
>  drivers/pci/hotplug/pciehp_hpc.c |  4 ++-
>  drivers/pci/pci.h                | 55 +++++++++++++-------------------
>  drivers/pci/pcie/dpc.c           | 27 ++++++++++++++++
>  drivers/pci/pcie/err.c           | 18 +++++++++--
>  4 files changed, 68 insertions(+), 36 deletions(-)
> 
> 
> base-commit: a1b8638ba1320e6684aa98233c15255eb803fac7
> -- 
> 2.18.4
>
Ethan Zhao Oct. 7, 2020, 7:33 a.m. UTC | #2 
Raj,

On Sun, Oct 4, 2020 at 12:57 PM Raj, Ashok <ashok.raj@linux.intel.com> wrote:
>
> Hi Ethan
>
> On Sat, Oct 03, 2020 at 03:55:09AM -0400, Ethan Zhao wrote:
> > Hi,folks,
> >
> > This simple patch set fixed some serious security issues found when DPC
> > error injection and NVMe SSD hotplug brute force test were doing -- race
> > condition between DPC handler and pciehp, AER interrupt handlers, caused
> > system hang and system with DPC feature couldn't recover to normal
> > working state as expected (NVMe instance lost, mount operation hang,
> > race PCIe access caused uncorrectable errors reported alternatively etc).
>
> I think maybe picking from other commit messages to make this description in
> cover letter bit clear. The fundamental premise is that when due to error
> conditions when events are processed by both DPC handler and hotplug handling of
> DLLSC both operating on the same device object ends up with crashes.

Yep, that's right.

Thanks,
Ethan
>
>
> >
> > With this patch set applied, stable 5.9-rc6 on ICS (Ice Lake SP platform,
> > see
> > https://en.wikichip.org/wiki/intel/microarchitectures/ice_lake_(server))
> >
> > could pass the PCIe Gen4 NVMe SSD brute force hotplug test with any time
> > interval between hot-remove and plug-in operation tens of times without
> > any errors occur and system works normal.
>
> >
> > With this patch set applied, system with DPC feature could recover from
> > NON-FATAL and FATAL errors injection test and works as expected.
> >
> > System works smoothly when errors happen while hotplug is doing, no
> > uncorrectable errors found.
> >
> > Brute DPC error injection script:
> >
> > for i in {0..100}
> > do
> >         setpci -s 64:02.0 0x196.w=000a
> >         setpci -s 65:00.0 0x04.w=0544
> >         mount /dev/nvme0n1p1 /root/nvme
> >         sleep 1
> > done
> >
> > Other details see every commits description part.
> >
> > This patch set could be applied to stable 5.9-rc6/rc7 directly.
> >
> > Help to review and test.
> >
> > v2: changed according to review by Andy Shevchenko.
> > v3: changed patch 4/5 to simpler coding.
> > v4: move function pci_wait_port_outdpc() to DPC driver and its
> >    declaration to pci.h. (tip from Christoph Hellwig <hch@infradead.org>).
> > v5: fix building issue reported by lkp@intel.com with some config.
> > v6: move patch[3/5] as the first patch according to Lukas's suggestion.
> >     and rewrite the comment part of patch[3/5].
> > v7: change the patch[4/5], based on Bjorn's code and truth table.
> >     change the patch[5/5] about the debug output information.
> >
> > Thanks,
> > Ethan
> >
> >
> > Ethan Zhao (5):
> >   PCI/ERR: get device before call device driver to avoid NULL pointer
> >     dereference
> >   PCI/DPC: define a function to check and wait till port finish DPC
> >     handling
> >   PCI: pciehp: check and wait port status out of DPC before handling
> >     DLLSC and PDC
> >   PCI: only return true when dev io state is really changed
> >   PCI/ERR: don't mix io state not changed and no driver together
> >
> >  drivers/pci/hotplug/pciehp_hpc.c |  4 ++-
> >  drivers/pci/pci.h                | 55 +++++++++++++-------------------
> >  drivers/pci/pcie/dpc.c           | 27 ++++++++++++++++
> >  drivers/pci/pcie/err.c           | 18 +++++++++--
> >  4 files changed, 68 insertions(+), 36 deletions(-)
> >
> >
> > base-commit: a1b8638ba1320e6684aa98233c15255eb803fac7
> > --
> > 2.18.4
> >