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powerpc/perf: POWER9 PMU stops after idle workaround

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POWER9 DD2 PMU can stop after a state-loss idle in some conditions.

A solution is to set then clear MMCRA[60] after wake from state-loss
idle. MMCRA[60] is a non-architected bit, see the user manual for
details.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Reviewed-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Acked-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nicholas Piggin 2017-07-20 11:53:22 +10:00 committed by Michael Ellerman
parent f29bb7861a
commit 09539f9b12
1 changed files with 7 additions and 1 deletions
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8
arch/powerpc/kernel/idle_book3s.S
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@ -460,11 +460,17 @@ pnv_restore_hyp_resource_arch300:
/*
* Workaround for POWER9, if we lost resources, the ERAT
* might have been mixed up and needs flushing. We also need
* to reload MMCR0 (see comment above).
* to reload MMCR0 (see comment above). We also need to set
* then clear bit 60 in MMCRA to ensure the PMU starts running.
*/
blt cr3,1f
PPC_INVALIDATE_ERAT
ld r1,PACAR1(r13)
mfspr r4,SPRN_MMCRA
ori r4,r4,(1 << (63-60))
mtspr SPRN_MMCRA,r4
xori r4,r4,(1 << (63-60))
mtspr SPRN_MMCRA,r4
ld r4,_MMCR0(r1)
mtspr SPRN_MMCR0,r4
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