Message ID | 1531902796-32294-1-git-send-email-ego@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | Accepted |
Commit | b03897cf318dfc47de33a7ecbc7655584266f034 |
Headers | show |
Series | [v2] powerpc/powernv : Save/Restore SPRG3 on entry/exit from stop. | expand |
Context | Check | Description |
---|---|---|
snowpatch_ozlabs/apply_patch | success | next/apply_patch Successfully applied |
snowpatch_ozlabs/checkpatch | success | Test checkpatch on branch next |
snowpatch_ozlabs/build-ppc64le | success | Test build-ppc64le on branch next |
snowpatch_ozlabs/build-ppc64be | success | Test build-ppc64be on branch next |
snowpatch_ozlabs/build-ppc64e | success | Test build-ppc64e on branch next |
snowpatch_ozlabs/build-ppc32 | success | Test build-ppc32 on branch next |
On Wed, 2018-07-18 at 08:33:16 UTC, "Gautham R. Shenoy" wrote: > From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> > > On 64-bit servers, SPRN_SPRG3 and its userspace read-only mirror > SPRN_USPRG3 are used as userspace VDSO write and read registers > respectively. > > SPRN_SPRG3 is lost when we enter stop4 and above, and is currently not > restored. As a result, any read from SPRN_USPRG3 returns zero on an > exit from stop4 and above. > > Thus in this situation, on POWER9, any call from sched_getcpu() always > returns zero, as on powerpc, we call __kernel_getcpu() which relies > upon SPRN_USPRG3 to report the CPU and NUMA node information. > > Fix this by restoring SPRN_SPRG3 on wake up from a deep stop state > with the sprg_vdso value that is cached in PACA. > > Fixes: e1c1cfed5432 ("powerpc/powernv: Save/Restore additional SPRs > for stop4 cpuidle") > > Reported-by: Florian Weimer <fweimer@redhat.com> > Cc: <stable@vger.kernel.org> # 4.14 > Cc: Oleg Nesterov <oleg@redhat.com> > Cc: Michael Neuling <mikey@neuling.org> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com> > Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/b03897cf318dfc47de33a7ecbc7655 cheers
diff --git a/arch/powerpc/kernel/idle_book3s.S b/arch/powerpc/kernel/idle_book3s.S index d85d551..672ead8 100644 --- a/arch/powerpc/kernel/idle_book3s.S +++ b/arch/powerpc/kernel/idle_book3s.S @@ -144,7 +144,9 @@ power9_restore_additional_sprs: mtspr SPRN_MMCR1, r4 ld r3, STOP_MMCR2(r13) + ld r4, PACA_SPRG_VDSO(r13) mtspr SPRN_MMCR2, r3 + mtspr SPRN_SPRG3, r4 blr /*