OpenCloudOS-Kernel/arch/powerpc
Benjamin Herrenschmidt ad98dd1a75 KVM: PPC: Book3S HV: Add more barriers in XIVE load/unload code
On POWER9 systems, we push the VCPU context onto the XIVE (eXternal
Interrupt Virtualization Engine) hardware when entering a guest,
and pull the context off the XIVE when exiting the guest.  The push
is done with cache-inhibited stores, and the pull with cache-inhibited
loads.

Testing has revealed that it is possible (though very rare) for
the stores to get reordered with the loads so that we end up with the
guest VCPU context still loaded on the XIVE after we have exited the
guest.  When that happens, it is possible for the same VCPU context
to then get loaded on another CPU, which causes the machine to
checkstop.

To fix this, we add I/O barrier instructions (eieio) before and
after the push and pull operations.  As partial compensation for the
potential slowdown caused by the extra barriers, we remove the eieio
instructions between the two stores in the push operation, and between
the two loads in the pull operation.  (The architecture requires
loads to cache-inhibited, guarded storage to be kept in order, and
requires stores to cache-inhibited, guarded storage likewise to be
kept in order, but allows such loads and stores to be reordered with
respect to each other.)

Reported-by: Carol L Soto <clsoto@us.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
2017-10-16 08:46:46 +11:00
..
boot powerpc: conditionally compile platform-specific serial drivers 2017-08-31 14:26:48 +10:00
configs powerpc/configs: Update for CONFIG_SND changes 2017-09-20 13:30:09 +10:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-05-02 15:53:46 -07:00
include Merge branch 'akpm' (patches from Andrew) 2017-09-09 10:30:07 -07:00
kernel powerpc fixes for 4.14 #4 2017-10-06 08:47:21 -07:00
kvm KVM: PPC: Book3S HV: Add more barriers in XIVE load/unload code 2017-10-16 08:46:46 +11:00
lib powerpc/sstep: mullw should calculate a 64 bit signed result 2017-09-20 13:30:09 +10:00
math-emu Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
mm powerpc/mm: Call flush_tlb_kernel_range with interrupts enabled 2017-10-04 22:15:30 +11:00
net powerpc updates for 4.14 2017-09-07 10:15:40 -07:00
oprofile ktime: Cleanup ktime_set() usage 2016-12-25 17:21:22 +01:00
perf powerpc/sysrq: Fix oops whem ppmu is not registered 2017-09-20 13:30:09 +10:00
platforms powerpc/powernv: Increase memory block size to 1GB on radix 2017-10-06 15:50:45 +11:00
purgatory powerpc/asm: Convert .llong directives to .8byte 2017-08-31 14:26:47 +10:00
sysdev powerpc fixes for 4.14 #4 2017-10-06 08:47:21 -07:00
tools powerpc/64: Tool to check head sections location sanity 2017-05-30 14:59:51 +10:00
xmon powerpc/xmon: Add ISA v3.0 SPRs to SPR dump 2017-08-31 14:26:45 +10:00
Kconfig powerpc updates for 4.14 2017-09-07 10:15:40 -07:00
Kconfig.debug powerpc/xmon: Enable disassembly files (compilation changes) 2017-02-15 20:02:42 +11:00
Makefile Merge branch 'fixes' into next 2017-08-23 22:20:10 +10:00
Makefile.postlink powerpc/64: Tool to check head sections location sanity 2017-05-30 14:59:51 +10:00