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

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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/powerpc/include/asm/cputable.h
View File

@ -212,6 +212,7 @@ static inline void cpu_feature_keys_init(void) { }
#define CPU_FTR_P9_TLBIE_STQ_BUG LONG_ASM_CONST(0x0000400000000000)
#define CPU_FTR_P9_TIDR LONG_ASM_CONST(0x0000800000000000)
#define CPU_FTR_P9_TLBIE_ERAT_BUG LONG_ASM_CONST(0x0001000000000000)
#define CPU_FTR_P9_RADIX_PREFETCH_BUG LONG_ASM_CONST(0x0002000000000000)
#ifndef __ASSEMBLY__
@ -459,8 +460,10 @@ static inline void cpu_feature_keys_init(void) { }
CPU_FTR_DBELL | CPU_FTR_HAS_PPR | CPU_FTR_ARCH_207S | \
CPU_FTR_TM_COMP | CPU_FTR_ARCH_300 | CPU_FTR_PKEY | \
CPU_FTR_P9_TLBIE_STQ_BUG | CPU_FTR_P9_TLBIE_ERAT_BUG | CPU_FTR_P9_TIDR)
#define CPU_FTRS_POWER9_DD2_0 CPU_FTRS_POWER9
#define CPU_FTRS_POWER9_DD2_1 (CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD2_1)
#define CPU_FTRS_POWER9_DD2_0 (CPU_FTRS_POWER9 | CPU_FTR_P9_RADIX_PREFETCH_BUG)
#define CPU_FTRS_POWER9_DD2_1 (CPU_FTRS_POWER9 | \
CPU_FTR_P9_RADIX_PREFETCH_BUG | \
CPU_FTR_POWER9_DD2_1)
#define CPU_FTRS_POWER9_DD2_2 (CPU_FTRS_POWER9 | CPU_FTR_POWER9_DD2_1 | \
CPU_FTR_P9_TM_HV_ASSIST | \
CPU_FTR_P9_TM_XER_SO_BUG)

13
arch/powerpc/kernel/dt_cpu_ftrs.c
View File

@ -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);

2
arch/powerpc/kvm/book3s_hv_rmhandlers.S
View File

@ -1801,6 +1801,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
tlbsync
ptesync
BEGIN_FTR_SECTION
/* Radix: Handle the case where the guest used an illegal PID */
LOAD_REG_ADDR(r4, mmu_base_pid)
lwz r3, VCPU_GUEST_PID(r9)
@ -1830,6 +1831,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
addi r7,r7,0x1000
bdnz 1b
ptesync
END_FTR_SECTION_IFSET(CPU_FTR_P9_RADIX_PREFETCH_BUG)
2:
#endif /* CONFIG_PPC_RADIX_MMU */

6
arch/powerpc/mm/book3s64/radix_pgtable.c
View File

@ -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

3
arch/powerpc/mm/book3s64/radix_tlb.c
View File

@ -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