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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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a83836dbc5
In guests without hotplugagble memory drmem structure is only zero
initialized. Trying to manipulate DLPAR parameters results in a crash.
$ echo "memory add count 1" > /sys/kernel/dlpar
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
...
NIP: c0000000000ff294 LR: c0000000000ff248 CTR: 0000000000000000
REGS: c0000000fb9d3880 TRAP: 0300 Tainted: G E (5.5.0-rc6-2-default)
MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE> CR: 28242428 XER: 20000000
CFAR: c0000000009a6c10 DAR: 0000000000000010 DSISR: 40000000 IRQMASK: 0
...
NIP dlpar_memory+0x6e4/0xd00
LR dlpar_memory+0x698/0xd00
Call Trace:
dlpar_memory+0x698/0xd00 (unreliable)
handle_dlpar_errorlog+0xc0/0x190
dlpar_store+0x198/0x4a0
kobj_attr_store+0x30/0x50
sysfs_kf_write+0x64/0x90
kernfs_fop_write+0x1b0/0x290
__vfs_write+0x3c/0x70
vfs_write+0xd0/0x260
ksys_write+0xdc/0x130
system_call+0x5c/0x68
Taking closer look at the code, I can see that for_each_drmem_lmb is a
macro expanding into `for (lmb = &drmem_info->lmbs[0]; lmb <=
&drmem_info->lmbs[drmem_info->n_lmbs - 1]; lmb++)`. When drmem_info->lmbs
is NULL, the loop would iterate through the whole address range if it
weren't stopped by the NULL pointer dereference on the next line.
This patch aligns for_each_drmem_lmb and for_each_drmem_lmb_in_range
macro behavior with the common C semantics, where the end marker does
not belong to the scanned range, and alters get_lmb_range() semantics.
As a side effect, the wraparound observed in the crash is prevented.
Fixes:
|
||
|---|---|---|
| .. | ||
| cmm.c | ||
| dlpar.c | ||
| dtl.c | ||
| eeh_pseries.c | ||
| event_sources.c | ||
| firmware.c | ||
| hotplug-cpu.c | ||
| hotplug-memory.c | ||
| hvCall_inst.c | ||
| hvCall.S | ||
| hvconsole.c | ||
| hvcserver.c | ||
| ibmebus.c | ||
| io_event_irq.c | ||
| iommu.c | ||
| Kconfig | ||
| kexec.c | ||
| lpar.c | ||
| lparcfg.c | ||
| Makefile | ||
| mobility.c | ||
| msi.c | ||
| nvram.c | ||
| of_helpers.c | ||
| of_helpers.h | ||
| offline_states.h | ||
| papr_scm.c | ||
| pci_dlpar.c | ||
| pci.c | ||
| pmem.c | ||
| power.c | ||
| pseries_energy.c | ||
| pseries.h | ||
| ras.c | ||
| reconfig.c | ||
| rng.c | ||
| rtas-fadump.c | ||
| rtas-fadump.h | ||
| scanlog.c | ||
| setup.c | ||
| smp.c | ||
| suspend.c | ||
| svm.c | ||
| vio.c | ||
| vphn.c | ||