From 736bcdd3a9fc672af33fb83230ecd0570ec38ec6 Mon Sep 17 00:00:00 2001 From: Jordan Niethe Date: Fri, 6 Dec 2019 14:17:22 +1100 Subject: 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 Acked-by: Paul Mackerras Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191206031722.25781-1-jniethe5@gmail.com --- arch/powerpc/mm/book3s64/radix_pgtable.c | 6 +++++- arch/powerpc/mm/book3s64/radix_tlb.c | 3 +++ 2 files changed, 8 insertions(+), 1 deletion(-) (limited to 'arch/powerpc/mm') 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 -- cgit v1.2.3