diff options
| author | Jordan Niethe <jniethe5@gmail.com> | 2019-12-06 06:17:22 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-01-25 16:11:37 +0300 |
| commit | 736bcdd3a9fc672af33fb83230ecd0570ec38ec6 (patch) | |
| tree | 46b27cba94fa34092b40826832ad1a41189d1b22 /arch/powerpc/mm | |
| parent | 5649607a8d0b0e019a4db14aab3de1e16c3a2b4f (diff) | |
| download | linux-736bcdd3a9fc672af33fb83230ecd0570ec38ec6.tar.xz | |
powerpc/mm: Remove kvm radix prefetch workaround for Power9 DD2.2
Commit a25bd72badfa ("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
Diffstat (limited to 'arch/powerpc/mm')
| -rw-r--r-- | arch/powerpc/mm/book3s64/radix_pgtable.c | 6 | ||||
| -rw-r--r-- | arch/powerpc/mm/book3s64/radix_tlb.c | 3 |
2 files changed, 8 insertions, 1 deletions
diff --git a/arch/powerpc/mm/book3s64/radix_pgtable.c b/arch/powerpc/mm/book3s64/radix_pgtable.c index 974109bb85db..dd1bea45325c 100644 --- a/arch/powerpc/mm/book3s64/radix_pgtable.c +++ b/arch/powerpc/mm/book3s64/radix_pgtable.c @@ -337,7 +337,11 @@ static void __init radix_init_pgtable(void) } /* Find out how many PID bits are supported */ - if (cpu_has_feature(CPU_FTR_HVMODE)) { + if (!cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) { + if (!mmu_pid_bits) + mmu_pid_bits = 20; + mmu_base_pid = 1; + } else if (cpu_has_feature(CPU_FTR_HVMODE)) { if (!mmu_pid_bits) mmu_pid_bits = 20; #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c index a95175c0972b..03f43c924e00 100644 --- a/arch/powerpc/mm/book3s64/radix_tlb.c +++ b/arch/powerpc/mm/book3s64/radix_tlb.c @@ -1161,6 +1161,9 @@ extern void radix_kvm_prefetch_workaround(struct mm_struct *mm) if (unlikely(pid == MMU_NO_CONTEXT)) return; + if (!cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) + return; + /* * If this context hasn't run on that CPU before and KVM is * around, there's a slim chance that the guest on another |