kernel.git/arch/powerpc/kernel/eeh_driver.c, branch linux-4.14.y

powerpc/powernv/iov: Ensure the pdn for VFs always contains a valid PE number

2020-02-28T15:35:56Z

[ Upstream commit 3b5b9997b331e77ce967eba2c4bc80dc3134a7fe ] On pseries there is a bug with adding hotplugged devices to an IOMMU group. For a number of dumb reasons fixing that bug first requires re-working how VFs are configured on PowerNV. For background, on PowerNV we use the pcibios_sriov_enable() hook to do two things: 1. Create a pci_dn structure for each of the VFs, and 2. Configure the PHB's internal BARs so the MMIO range for each VF maps to a unique PE. Roughly speaking a PE is the hardware counterpart to a Linux IOMMU group since all the devices in a PE share the same IOMMU table. A PE also defines the set of devices that should be isolated in response to a PCI error (i.e. bad DMA, UR/CA, AER events, etc). When isolated all MMIO and DMA traffic to and from devicein the PE is blocked by the root complex until the PE is recovered by the OS. The requirement to block MMIO causes a giant headache because the P8 PHB generally uses a fixed mapping between MMIO addresses and PEs. As a result we need to delay configuring the IOMMU groups for device until after MMIO resources are assigned. For physical devices (i.e. non-VFs) the PE assignment is done in pcibios_setup_bridge() which is called immediately after the MMIO resources for downstream devices (and the bridge's windows) are assigned. For VFs the setup is more complicated because: a) pcibios_setup_bridge() is not called again when VFs are activated, and b) The pci_dev for VFs are created by generic code which runs after pcibios_sriov_enable() is called. The work around for this is a two step process: 1. A fixup in pcibios_add_device() is used to initialised the cached pe_number in pci_dn, then 2. A bus notifier then adds the device to the IOMMU group for the PE specified in pci_dn->pe_number. A side effect fixing the pseries bug mentioned in the first paragraph is moving the fixup out of pcibios_add_device() and into pcibios_bus_add_device(), which is called much later. This results in step 2. failing because pci_dn->pe_number won't be initialised when the bus notifier is run. We can fix this by removing the need for the fixup. The PE for a VF is known before the VF is even scanned so we can initialise pci_dn->pe_number pcibios_sriov_enable() instead. Unfortunately, moving the initialisation causes two problems: 1. We trip the WARN_ON() in the current fixup code, and 2. The EEH core clears pdn->pe_number when recovering a VF and relies on the fixup to correctly re-set it. The only justification for either of these is a comment in eeh_rmv_device() suggesting that pdn->pe_number *must* be set to IODA_INVALID_PE in order for the VF to be scanned. However, this comment appears to have no basis in reality. Both bugs can be fixed by just deleting the code. Tested-by: Alexey Kardashevskiy Reviewed-by: Alexey Kardashevskiy Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191028085424.12006-1-oohall@gmail.com Signed-off-by: Sasha Levin

powerpc/eeh: Fix use-after-release of EEH driver

2018-08-03T05:50:24Z

[ Upstream commit 46d4be41b987a6b2d25a2ebdd94cafb44e21d6c5 ] Correct two cases where eeh_pcid_get() is used to reference the driver's module but the reference is dropped before the driver pointer is used. In eeh_rmv_device() also refactor a little so that only two calls to eeh_pcid_put() are needed, rather than three and the reference isn't taken at all if it wasn't needed. Signed-off-by: Sam Bobroff Signed-off-by: Michael Ellerman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Fix race with driver un/bind

2018-05-01T19:58:27Z

commit f0295e047fcf52ccb42561fb7de6942f5201b676 upstream. The current EEH callbacks can race with a driver unbind. This can result in a backtraces like this: EEH: Frozen PHB#0-PE#1fc detected EEH: PE location: S000009, PHB location: N/A CPU: 2 PID: 2312 Comm: kworker/u258:3 Not tainted 4.15.6-openpower1 #2 Workqueue: nvme-wq nvme_reset_work [nvme] Call Trace: dump_stack+0x9c/0xd0 (unreliable) eeh_dev_check_failure+0x420/0x470 eeh_check_failure+0xa0/0xa4 nvme_reset_work+0x138/0x1414 [nvme] process_one_work+0x1ec/0x328 worker_thread+0x2e4/0x3a8 kthread+0x14c/0x154 ret_from_kernel_thread+0x5c/0xc8 nvme nvme1: Removing after probe failure status: -19 cpu 0x23: Vector: 300 (Data Access) at [c000000ff50f3800] pc: c0080000089a0eb0: nvme_error_detected+0x4c/0x90 [nvme] lr: c000000000026564: eeh_report_error+0xe0/0x110 sp: c000000ff50f3a80 msr: 9000000000009033 dar: 400 dsisr: 40000000 current = 0xc000000ff507c000 paca = 0xc00000000fdc9d80 softe: 0 irq_happened: 0x01 pid = 782, comm = eehd Linux version 4.15.6-openpower1 (smc@smc-desktop) (gcc version 6.4.0 (Buildroot 2017.11.2-00008-g4b6188e)) #2 SM P Tue Feb 27 12:33:27 PST 2018 enter ? for help eeh_report_error+0xe0/0x110 eeh_pe_dev_traverse+0xc0/0xdc eeh_handle_normal_event+0x184/0x4c4 eeh_handle_event+0x30/0x288 eeh_event_handler+0x124/0x170 kthread+0x14c/0x154 ret_from_kernel_thread+0x5c/0xc8 The first part is an EEH (on boot), the second half is the resulting crash. nvme probe starts the nvme_reset_work() worker thread. This worker thread starts touching the device which see a device error (EEH) and hence queues up an event in the powerpc EEH worker thread. nvme_reset_work() then continues and runs nvme_remove_dead_ctrl_work() which results in unbinding the driver from the device and hence releases all resources. At the same time, the EEH worker thread starts doing the EEH .error_detected() driver callback, which no longer works since the resources have been freed. This fixes the problem in the same way the generic PCIe AER code (in drivers/pci/pcie/aer/aerdrv_core.c) does. It makes the EEH code hold the device_lock() while performing the driver EEH callbacks and associated code. This ensures either the callbacks are no longer register, or if they are registered the driver will not be removed from underneath us. This has been broken forever. The EEH call backs were first introduced in 2005 (in 77bd7415610) but it's not clear if a lock was needed back then. Fixes: 77bd74156101 ("[PATCH] powerpc: PCI Error Recovery: PPC64 core recovery routines") Cc: stable@vger.kernel.org # v2.6.16+ Signed-off-by: Michael Neuling Reviewed-by: Benjamin Herrenschmidt Signed-off-by: Michael Ellerman Signed-off-by: Greg Kroah-Hartman

powerpc/eeh: Remove unnecessary pointer to phb from eeh_dev

2017-08-31T04:26:09Z

The eeh_dev struct already holds a pointer to pci_dn which it does not exist without and pci_dn itself holds the very same pointer so just use it. Signed-off-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman

powerpc/eeh: Clean up and document event handling functions

2017-05-02T12:41:43Z

Remove unnecessary tags in eeh_handle_normal_event(), and add function comments for eeh_handle_normal_event() and eeh_handle_special_event(). The only functional difference is that in the case of a PE reaching the maximum number of failures, rather than one message telling you of this and suggesting you reseat the device, there are two separate messages. Suggested-by: Alexey Kardashevskiy Signed-off-by: Russell Currey Reviewed-by: Andrew Donnellan Reviewed-by: Gavin Shan Signed-off-by: Michael Ellerman

powerpc/eeh: Avoid use after free in eeh_handle_special_event()

2017-05-02T12:41:43Z

eeh_handle_special_event() is called when an EEH event is detected but can't be narrowed down to a specific PE. This function looks through every PE to find one in an erroneous state, then calls the regular event handler eeh_handle_normal_event() once it knows which PE has an error. However, if eeh_handle_normal_event() found that the PE cannot possibly be recovered, it will free it, rendering the passed PE stale. This leads to a use after free in eeh_handle_special_event() as it attempts to clear the "recovering" state on the PE after eeh_handle_normal_event() returns. Thus, make sure the PE is valid when attempting to clear state in eeh_handle_special_event(). Fixes: 8a6b1bc70dbb ("powerpc/eeh: EEH core to handle special event") Cc: stable@vger.kernel.org # v3.11+ Reported-by: Alexey Kardashevskiy Signed-off-by: Russell Currey Reviewed-by: Gavin Shan Signed-off-by: Michael Ellerman

powerpc/eeh: Fix wrong flag passed to eeh_unfreeze_pe()

2017-01-24T10:22:51Z

In __eeh_clear_pe_frozen_state(), we should pass the flag's value instead of its address to eeh_unfreeze_pe(). The isolated flag is cleared if no error returned from __eeh_clear_pe_frozen_state(). We never observed the error from the function. So the isolated flag should have been always cleared, no real issue is caused because of the misused @flag. This fixes the code by passing the value of @flag to eeh_unfreeze_pe(). Fixes: 5cfb20b96f6 ("powerpc/eeh: Emulate EEH recovery for VFIO devices") Cc: stable@vger.kernel.org # v3.18+ Signed-off-by: Gavin Shan Signed-off-by: Michael Ellerman

Merge tag 'powerpc-4.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

2016-12-16T17:26:42Z

Pull powerpc updates from Michael Ellerman: "Highlights include: - Support for the kexec_file_load() syscall, which is a prereq for secure and trusted boot. - Prevent kernel execution of userspace on P9 Radix (similar to SMEP/PXN). - Sort the exception tables at build time, to save time at boot, and store them as relative offsets to save space in the kernel image & memory. - Allow building the kernel with thin archives, which should allow us to build an allyesconfig once some other fixes land. - Build fixes to allow us to correctly rebuild when changing the kernel endian from big to little or vice versa. - Plumbing so that we can avoid doing a full mm TLB flush on P9 Radix. - Initial stack protector support (-fstack-protector). - Support for dumping the radix (aka. Linux) and hash page tables via debugfs. - Fix an oops in cxl coredump generation when cxl_get_fd() is used. - Freescale updates from Scott: "Highlights include 8xx hugepage support, qbman fixes/cleanup, device tree updates, and some misc cleanup." - Many and varied fixes and minor enhancements as always. Thanks to: Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V, Anshuman Khandual, Anton Blanchard, Balbir Singh, Bartlomiej Zolnierkiewicz, Christophe Jaillet, Christophe Leroy, Denis Kirjanov, Elimar Riesebieter, Frederic Barrat, Gautham R. Shenoy, Geliang Tang, Geoff Levand, Jack Miller, Johan Hovold, Lars-Peter Clausen, Libin, Madhavan Srinivasan, Michael Neuling, Nathan Fontenot, Naveen N. Rao, Nicholas Piggin, Pan Xinhui, Peter Senna Tschudin, Rashmica Gupta, Rui Teng, Russell Currey, Scott Wood, Simon Guo, Suraj Jitindar Singh, Thiago Jung Bauermann, Tobias Klauser, Vaibhav Jain" [ And thanks to Michael, who took time off from a new baby to get this pull request done. - Linus ] * tag 'powerpc-4.10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (174 commits) powerpc/fsl/dts: add FMan node for t1042d4rdb powerpc/fsl/dts: add sg_2500_aqr105_phy4 alias on t1024rdb powerpc/fsl/dts: add QMan and BMan nodes on t1024 powerpc/fsl/dts: add QMan and BMan nodes on t1023 soc/fsl/qman: test: use DEFINE_SPINLOCK() powerpc/fsl-lbc: use DEFINE_SPINLOCK() powerpc/8xx: Implement support of hugepages powerpc: get hugetlbpage handling more generic powerpc: port 64 bits pgtable_cache to 32 bits powerpc/boot: Request no dynamic linker for boot wrapper soc/fsl/bman: Use resource_size instead of computation soc/fsl/qe: use builtin_platform_driver powerpc/fsl_pmc: use builtin_platform_driver powerpc/83xx/suspend: use builtin_platform_driver powerpc/ftrace: Fix the comments for ftrace_modify_code powerpc/perf: macros for power9 format encoding powerpc/perf: power9 raw event format encoding powerpc/perf: update attribute_group data structure powerpc/perf: factor out the event format field powerpc/mm/iommu, vfio/spapr: Put pages on VFIO container shutdown ...

powerpc/eeh: Fix deadlock when PE frozen state can't be cleared

2016-12-01T11:26:27Z

In eeh_reset_device(), we take the pci_rescan_remove_lock immediately after after we call eeh_reset_pe() to reset the PCI controller. We then call eeh_clear_pe_frozen_state(), which can return an error. In this case, we bail out of eeh_reset_device() without calling pci_unlock_rescan_remove(). Add a call to pci_unlock_rescan_remove() in the eeh_clear_pe_frozen_state() error path so that we don't cause a deadlock later on. Reported-by: Pradipta Ghosh Fixes: 78954700631f ("powerpc/eeh: Avoid I/O access during PE reset") Cc: stable@vger.kernel.org # v3.16+ Signed-off-by: Andrew Donnellan Acked-by: Russell Currey Signed-off-by: Michael Ellerman

powerpc/eeh: Refactor EEH PE reset functions

2016-11-22T00:57:08Z

eeh_pe_reset and eeh_reset_pe are two different functions in the same file which do mostly the same thing. Not only is this confusing, but potentially causes disrepancies in functionality, notably eeh_reset_pe as it does not check return values for failure. Refactor this into the following: - eeh_pe_reset(): stays as is, performs a single operation, exported - eeh_pe_reset_full(): new, full reset process that calls eeh_pe_reset() - eeh_reset_pe(): removed and replaced by eeh_pe_reset_full() - eeh_reset_pe_once(): removed Signed-off-by: Russell Currey Signed-off-by: Michael Ellerman