On Wed Jan 29, 2025 at 8:53 AM AEST, Paul Mackerras wrote:
> Power ISA v3.1 implementations in the Linux Compliancy Subset and
> lower are not required to implement broadcast TLBIE, and in fact
> Microwatt doesn't. To avoid the need to specify "disable_tlbie" on
> the kernel command line on SMP Microwatt systems, this defines a
> config option that asserts that broadcast TLBIE should never be used
> (the kernel will instead use IPIs to trigger local TLBIEs on other
> CPUs when required).
>
> Signed-off-by: Paul Mackerras <pau...@ozlabs.org>
> ---
> arch/powerpc/mm/book3s64/pgtable.c | 10 ++++++++--
> arch/powerpc/platforms/Kconfig.cputype | 12 ++++++++++++
> arch/powerpc/platforms/microwatt/Kconfig | 1 +
> 3 files changed, 21 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/mm/book3s64/pgtable.c
> b/arch/powerpc/mm/book3s64/pgtable.c
> index 374542528080..14ee96e2a581 100644
> --- a/arch/powerpc/mm/book3s64/pgtable.c
> +++ b/arch/powerpc/mm/book3s64/pgtable.c
> @@ -588,10 +588,16 @@ int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
> }
> #endif
>
> +#ifndef CONFIG_PPC_RADIX_NO_BROADCAST_TLBIE
Hate to bikeshed, but would it be annoying to make this an affirmative
option?
> +#define DEFAULT_TLBIE_ENABLE true
> +#else
> +#define DEFAULT_TLBIE_ENABLE false
> +#endif
> +
> /*
> * Does the CPU support tlbie?
> */
> -bool tlbie_capable __read_mostly = true;
> +bool tlbie_capable __read_mostly = DEFAULT_TLBIE_ENABLE;
> EXPORT_SYMBOL(tlbie_capable);
>
> /*
> @@ -599,7 +605,7 @@ EXPORT_SYMBOL(tlbie_capable);
> * address spaces? tlbie may still be used for nMMU accelerators, and for KVM
> * guest address spaces.
> */
> -bool tlbie_enabled __read_mostly = true;
> +bool tlbie_enabled __read_mostly = DEFAULT_TLBIE_ENABLE;
>
> static int __init setup_disable_tlbie(char *str)
> {
> diff --git a/arch/powerpc/platforms/Kconfig.cputype
> b/arch/powerpc/platforms/Kconfig.cputype
> index 1453ccc900c4..bd2a4e46ab34 100644
> --- a/arch/powerpc/platforms/Kconfig.cputype
> +++ b/arch/powerpc/platforms/Kconfig.cputype
> @@ -449,6 +449,18 @@ config PPC_RADIX_MMU_DEFAULT
>
> If you're unsure, say Y.
>
> +config PPC_RADIX_NO_BROADCAST_TLBIE
> + depends on PPC_RADIX_MMU
> + help
> + Power ISA v3.1 implementations in the Linux Compliancy Subset
> + and lower are not required to implement broadcast TLBIE
> + instructions, that is, a TLB invalidation instruction
> + performed on one CPU is not required to operate on the TLBs
> + in all CPUs in the system. Instead, the kernel does an IPI
> + to each relevant CPU to get it to do a local TLBIE instruction.
> + Select this option to force global invalidations to be done via
> + IPIs unconditionally.
... when using radix MMU. Hash MMU requires broadcast TLBIE.
Nitpicks aside, looks okay to me.
Reviewed-by: Nicholas Piggin <npig...@gmail.com>
> +
> config PPC_KERNEL_PREFIXED
> depends on PPC_HAVE_PREFIXED_SUPPORT
> depends on CC_HAS_PREFIXED
> diff --git a/arch/powerpc/platforms/microwatt/Kconfig
> b/arch/powerpc/platforms/microwatt/Kconfig
> index 5e41adadac1f..1d5cc1ae3636 100644
> --- a/arch/powerpc/platforms/microwatt/Kconfig
> +++ b/arch/powerpc/platforms/microwatt/Kconfig
> @@ -7,6 +7,7 @@ config PPC_MICROWATT
> select PPC_ICP_NATIVE
> select PPC_UDBG_16550
> select COMMON_CLK
> + select PPC_RADIX_NO_BROADCAST_TLBIE
> help
> This option enables support for FPGA-based Microwatt
> implementations.
>
