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powerpc/mm: Remove kvm radix prefetch workaround for Power9 DD2.2

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Commit a25bd72bad ("powerpc/mm/radix: Workaround prefetch issue with
KVM") introduced a number of workarounds as coming out of a guest with
the mmu enabled would make the cpu would start running in hypervisor
state with the PID value from the guest. The cpu will then start
prefetching for the hypervisor with that PID value.

In Power9 DD2.2 the cpu behaviour was modified to fix this. When
accessing Quadrant 0 in hypervisor mode with LPID != 0 prefetching will
not be performed. This means that we can get rid of the workarounds for
Power9 DD2.2 and later revisions. Add a new cpu feature
CPU_FTR_P9_RADIX_PREFETCH_BUG to indicate if the workarounds are needed.

Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191206031722.25781-1-jniethe5@gmail.com
This commit is contained in:
Jordan Niethe
2019-12-06 14:17:22 +11:00
committed by Michael Ellerman
parent 5649607a8d
commit 736bcdd3a9
5 changed files with 23 additions and 8 deletions
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13
arch/powerpc/kernel/dt_cpu_ftrs.c
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@@ -727,17 +727,20 @@ static __init void cpufeatures_cpu_quirks(void)
/*
* Not all quirks can be derived from the cpufeatures device tree.
*/
if ((version & 0xffffefff) == 0x004e0200)
; /* DD2.0 has no feature flag */
else if ((version & 0xffffefff) == 0x004e0201)
if ((version & 0xffffefff) == 0x004e0200) {
/* DD2.0 has no feature flag */
cur_cpu_spec->cpu_features |= CPU_FTR_P9_RADIX_PREFETCH_BUG;
} else if ((version & 0xffffefff) == 0x004e0201) {
cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
else if ((version & 0xffffefff) == 0x004e0202) {
cur_cpu_spec->cpu_features |= CPU_FTR_P9_RADIX_PREFETCH_BUG;
} else if ((version & 0xffffefff) == 0x004e0202) {
cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_HV_ASSIST;
cur_cpu_spec->cpu_features |= CPU_FTR_P9_TM_XER_SO_BUG;
cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
} else if ((version & 0xffff0000) == 0x004e0000)
} else if ((version & 0xffff0000) == 0x004e0000) {
/* DD2.1 and up have DD2_1 */
cur_cpu_spec->cpu_features |= CPU_FTR_POWER9_DD2_1;
}
if ((version & 0xffff0000) == 0x004e0000) {
cur_cpu_spec->cpu_features &= ~(CPU_FTR_DAWR);