linux-dev/arch/powerpc/platforms/pseries/eeh_pseries.c, branch linus/master

powerpc/eeh: Drop redundant spinlock initialization

2022-05-22T05:58:31Z

slot_errbuf_lock has declared and initialized by DEFINE_SPINLOCK, so we don't need to spin_lock_init again, drop it. Signed-off-by: Haowen Bai Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/1652232476-9696-1-git-send-email-baihaowen@meizu.com

powerpc: fix typos in comments

2022-05-05T12:12:44Z

Various spelling mistakes in comments. Detected with the help of Coccinelle. Signed-off-by: Julia Lawall Reviewed-by: Joel Stanley Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220430185654.5855-1-Julia.Lawall@inria.fr

powerpc/eeh: Remove unused inline functions

2022-05-04T11:44:02Z

pseries_eeh_init_edev() is used exclusively in eeh_pseries.c, make it static and remove unused inline function. pseries_eeh_init_edev_recursive() is only called from files build wich CONFIG_HOTPLUG_PCI_RPA which depends on CONFIG_PSERIES and CONFIG_EEH, so can remove the unused inline version. Suggested-by: Christophe Leroy Signed-off-by: YueHaibing Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220316104239.26508-1-yuehaibing@huawei.com

pseries/eeh: Fix the kdump kernel crash during eeh_pseries_init

2021-10-07T12:37:22Z

On pseries LPAR when an empty slot is assigned to partition OR in single LPAR mode, kdump kernel crashes during issuing PHB reset. In the kdump scenario, we traverse all PHBs and issue reset using the pe_config_addr of the first child device present under each PHB. However the code assumes that none of the PHB slots can be empty and uses list_first_entry() to get the first child device under the PHB. Since list_first_entry() expects the list to be non-empty, it returns an invalid pci_dn entry and ends up accessing NULL phb pointer under pci_dn->phb causing kdump kernel crash. This patch fixes the below kdump kernel crash by skipping empty slots: audit: initializing netlink subsys (disabled) thermal_sys: Registered thermal governor 'fair_share' thermal_sys: Registered thermal governor 'step_wise' cpuidle: using governor menu pstore: Registered nvram as persistent store backend Issue PHB reset ... audit: type=2000 audit(1631267818.000:1): state=initialized audit_enabled=0 res=1 BUG: Kernel NULL pointer dereference on read at 0x00000268 Faulting instruction address: 0xc000000008101fb0 Oops: Kernel access of bad area, sig: 7 [#1] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=2048 NUMA pSeries Modules linked in: CPU: 7 PID: 1 Comm: swapper/7 Not tainted 5.14.0 #1 NIP: c000000008101fb0 LR: c000000009284ccc CTR: c000000008029d70 REGS: c00000001161b840 TRAP: 0300 Not tainted (5.14.0) MSR: 8000000002009033 CR: 28000224 XER: 20040002 CFAR: c000000008101f0c DAR: 0000000000000268 DSISR: 00080000 IRQMASK: 0 ... NIP pseries_eeh_get_pe_config_addr+0x100/0x1b0 LR __machine_initcall_pseries_eeh_pseries_init+0x2cc/0x350 Call Trace: 0xc00000001161bb80 (unreliable) __machine_initcall_pseries_eeh_pseries_init+0x2cc/0x350 do_one_initcall+0x60/0x2d0 kernel_init_freeable+0x350/0x3f8 kernel_init+0x3c/0x17c ret_from_kernel_thread+0x5c/0x64 Fixes: 5a090f7c363fd ("powerpc/pseries: PCIE PHB reset") Signed-off-by: Mahesh Salgaonkar [mpe: Tweak wording and trim oops] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/163215558252.413351.8600189949820258982.stgit@jupiter

powerpc/pseries/eeh: Make pseries_send_allow_unfreeze() static

2021-01-30T00:39:31Z

Only used locally. It fixes this W=1 compile error : ../arch/powerpc/platforms/pseries/eeh_pseries.c:697:5: error: no previous prototype for ‘pseries_send_allow_unfreeze’ [-Werror=missing-prototypes] 697 | int pseries_send_allow_unfreeze(struct pci_dn *pdn, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~ Signed-off-by: Cédric Le Goater Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210104143206.695198-24-clg@kaod.org

powerpc/pseries/eeh: Make pseries_pcibios_bus_add_device() static

2021-01-30T00:39:27Z

pseries_pcibios_bus_add_device() is a local routine defining the pcibios_bus_add_device() handler of the pseries machine in eeh_pseries_init(). It doesn't need to be external. It fixes this W=1 compile error: ../arch/powerpc/platforms/pseries/eeh_pseries.c:46:6: error: no previous prototype for ‘pseries_pcibios_bus_add_device’ [-Werror=missing-prototypes] 46 | void pseries_pcibios_bus_add_device(struct pci_dev *pdev) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Fixes: dae7253f9f78 ("powerpc/pseries: Add pseries SR-IOV Machine dependent calls") Signed-off-by: Cédric Le Goater Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210104143206.695198-4-clg@kaod.org

powerpc/pseries/eeh: Fix use of uninitialised variable

2020-10-07T11:34:47Z

If the RTAS call to query the PE address for a device fails we jump the err: label where an error message is printed along with the return code. However, the printed return code is from the "ret" variable which isn't set at that point since we assigned the result to "addr" instead. Fix this by consistently using the "ret" variable for the result of the RTAS call helpers an dropping the "addr" local variable" Fixes: 98ba956f6a38 ("powerpc/pseries/eeh: Rework device EEH PE determination") Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201007040903.819081-2-oohall@gmail.com

powerpc/eeh: Clean up PE addressing

2020-10-06T12:22:25Z

When support for EEH on PowerNV was added a lot of pseries specific code was made "generic" and some of the quirks of pseries EEH came along for the ride. One of the stranger quirks is eeh_pe containing two types of PE address: pe->addr and pe->config_addr. There reason for this appears to be historical baggage rather than any real requirements. On pseries EEH PEs are manipulated using RTAS calls. Each EEH RTAS call takes a "PE configuration address" as an input which is used to identify which EEH PE is being manipulated by the call. When initialising the EEH state for a device the first thing we need to do is determine the configuration address for the PE which contains the device so we can enable EEH on that PE. This process is outlined in PAPR which is the modern (i.e post-2003) FW specification for pseries. However, EEH support was first described in the pSeries RISC Platform Architecture (RPA) and although they are mostly compatible EEH is one of the areas where they are not. The major difference is that RPA doesn't actually have the concept of a PE. On RPA systems the EEH RTAS calls are done on a per-device basis using the same config_addr that would be passed to the RTAS functions to access PCI config space (e.g. ibm,read-pci-config). The config_addr is not identical since the function and config register offsets of the config_addr must be set to zero. EEH operations being done on a per-device basis doesn't make a whole lot of sense when you consider how EEH was implemented on legacy PCI systems. For legacy PCI(-X) systems EEH was implemented using special PCI-PCI bridges which contained logic to detect errors and freeze the secondary bus when one occurred. This means that the EEH enabled state is shared among all devices behind that EEH bridge. As a result there's no way to implement the per-device control required for the semantics specified by RPA. It can be made to work if we assume that a separate EEH bridge exists for each EEH capable PCI slot and there are no bridges behind those slots. However, RPA also specifies the ibm,configure-bridge RTAS call for re-initalising bridges behind EEH capable slots after they are reset due to an EEH event so that is probably not a valid assumption. This incoherence was fixed in later PAPR, which succeeded RPA. Unfortunately, since Linux EEH support seems to have been implemented based on the RPA spec some of the legacy assumptions were carried over (probably for POWER4 compatibility). The fix made in PAPR was the introduction of the "PE" concept and redefining the EEH RTAS calls (set-eeh-option, reset-slot, etc) to operate on a per-PE basis so all devices behind an EEH bride would share the same EEH state. The "config_addr" argument to the EEH RTAS calls became the "PE_config_addr" and the OS was required to use the ibm,get-config-addr-info RTAS call to find the correct PE address for the device. When support for the new interfaces was added to Linux it was implemented using something like: At probe time: pdn->eeh_config_addr = rtas_config_addr(pdn); pdn->eeh_pe_config_addr = rtas_get_config_addr_info(pdn); When performing an RTAS call: config_addr = pdn->eeh_config_addr; if (pdn->eeh_pe_config_addr) config_addr = pdn->eeh_pe_config_addr; rtas_call(..., config_addr, ...); In other words, if the ibm,get-config-addr-info RTAS call is implemented and returned a valid result we'd use that as the argument to the EEH RTAS calls. If not, Linux would fall back to using the device's config_addr. Over time these addresses have moved around going from pci_dn to eeh_dev and finally into eeh_pe. Today the users look like this: config_addr = pe->config_addr; if (pe->addr) config_addr = pe->addr; rtas_call(..., config_addr, ...); However, considering the EEH core always operates on a per-PE basis and even on pseries the only per-device operation is the initial call to ibm,set-eeh-option I'm not sure if any of this actually works on an RPA system today. It doesn't make much sense to have the fallback address in a generic structure either since the bulk of the code which reference it is in pseries anyway. The EEH core makes a token effort to support looking up a PE using the config_addr by having two arguments to eeh_pe_get(). However, a survey of all the callers to eeh_pe_get() shows that all bar one have the config_addr argument hard-coded to zero.The only caller that doesn't is in eeh_pe_tree_insert() which has: if (!eeh_has_flag(EEH_VALID_PE_ZERO) && !edev->pe_config_addr) return -EINVAL; pe = eeh_pe_get(hose, edev->pe_config_addr, edev->bdfn); The third argument (config_addr) is only used if the second (pe->addr) argument is invalid. The preceding check ensures that the call to eeh_pe_get() will never happen if edev->pe_config_addr is invalid so there is no situation where eeh_pe_get() will search for a PE based on the 3rd argument. The check also means that we'll never insert a PE into the tree where pe_config_addr is zero since EEH_VALID_PE_ZERO is never set on pseries. All the users of the fallback address on pseries never actually use the fallback and all the only caller that supplies something for the config_addr argument to eeh_pe_get() never use it either. It's all dead code. This patch removes the fallback address from eeh_pe since nothing uses it. Specificly, we do this by: 1) Removing pe->config_addr 2) Removing the EEH_VALID_PE_ZERO flag 3) Removing the fallback address argument to eeh_pe_get(). 4) Removing all the checks for pe->addr being zero in the pseries EEH code. This leaves us with PE's only being identified by what's in their pe->addr field and the EEH core relying on the platform to ensure that eeh_dev's are only inserted into the EEH tree if they're actually inside a PE. No functional changes, I hope. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200918093050.37344-9-oohall@gmail.com

powerpc/pseries/eeh: Allow zero to be a valid PE configuration address

2020-10-06T12:22:25Z

There's no real reason why zero can't be a valid PE configuration address. Under qemu each sPAPR PHB (i.e. EEH supporting) has the passed-though devices on bus zero, so the PE address of bus :00 should be zero. However, all previous versions of Linux will reject that, so Qemu at least goes out of it's way to avoid it. The Qemu implementation of ibm,get-config-addr-info2 RTAS has the following comment: > /* > * We always have PE address of form "00BB0001". "BB" > * represents the bus number of PE's primary bus. > */ So qemu puts a one into the register portion of the PE's config_addr to avoid it being zero. The whole is pretty silly considering that RTAS will return a negative error code if it can't map the device's config_addr to a PE. This patch fixes Linux to treat zero as a valid PE address. This shouldn't have any real effects due to the Qemu hack mentioned above. And the fact that Linux EEH has worked historically on PowerVM means they never pass through devices on bus zero so we would never see the problem there either. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200918093050.37344-8-oohall@gmail.com

powerpc/pseries/eeh: Rework device EEH PE determination

2020-10-06T12:22:25Z

The process Linux uses for determining if a device supports EEH or not appears to be at odds with what PAPR says the OS should be doing. The current flow is something like: 1. Assume pe_config_addr is equal the the device's config_addr. 2. Attempt to enable EEH on that PE 3. Verify EEH was enabled (POWER4 bug workaround) 4. Try find the pe_config_addr using the ibm,get-config-addr-info2 RTAS call. 5. If that fails walk the pci_dn tree upwards trying to find a parent device with EEH support. If we find one then add the device to that PE. The first major problem with this process is that we need the PE config address in step 2) since its needs to be passed to the ibm,set-eeh-option RTAS call when enabling EEH for th PE. We hack around this requirement in by making the assumption in 1) and delay finding the actual PE address until 4). This is fine if: a) The PCI device is the 0th function, and b) The device is on the PE's root bus. Granted, the current sequence does appear to work on most systems even when these conditions are false. At a guess PowerVM's RTAS has workarounds to accommodate Linux's quirks or the RTAS call to enable EEH is treated as no-op on most platforms since EEH is usually enabled by default. However, what is currently implemented is a bit sketch and is downright confusing since it doesn't match up with what what PAPR suggests we should be doing. This patch re-works how we handle EEH init so that we find the PE config address using the ibm,get-config-addr-info2 RTAS call first, then use the found address to finish the EEH init process. It also drops the Power4 workaround since as of commit 471d7ff8b51b ("powerpc/64s: Remove POWER4 support") the kernel does not support running on a Power4 CPU so there's no need to support the Power4 platform's quirks either. With the patch applied the sequence is now: 1. Find the pe_config_addr from the device using the RTAS call. 2. Enable the PE. 3. Insert the edev into the tree and create an eeh_pe if needed. The other change made here is ignoring unsupported devices entirely. Currently the device's BARs are saved to the eeh_dev even if the device is not part of an EEH PE. Not being part of a PE means that an EEH recovery pass will never see that device so the saving the BARs is pointless. Signed-off-by: Oliver O'Halloran Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200918093050.37344-7-oohall@gmail.com