diff options
| author | Paul Burton <paul.burton@imgtec.com> | 2017-06-03 00:38:01 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2017-06-29 02:42:29 +0200 |
| commit | e7bc8557428f069eaa613b3676ea6931c0f7fe43 (patch) | |
| tree | c7f4f7a8b42f6c974159eef349eb041b5ea7b570 /arch/mips/include/asm/cpu-features.h | |
| parent | MIPS: CPS: Handle spurious VP starts more gracefully (diff) | |
| download | linux-e7bc8557428f069eaa613b3676ea6931c0f7fe43.tar.xz linux-e7bc8557428f069eaa613b3676ea6931c0f7fe43.zip | |
MIPS: Add CPU shared FTLB feature detection
Some systems share FTLB RAMs or entries between sibling CPUs (ie.
hardware threads, or VP(E)s, within a core). These properties require
kernel handling in various places. As a start this patch introduces
cpu_has_shared_ftlb_ram & cpu_has_shared_ftlb_entries feature macros
which we set appropriately for I6400 & I6500 CPUs. Further patches will
make use of these macros as appropriate.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16202/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/include/asm/cpu-features.h')
| -rw-r--r-- | arch/mips/include/asm/cpu-features.h | 41 |
1 files changed, 41 insertions, 0 deletions
diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h index 494d38274142..d6ea8e7c5107 100644 --- a/arch/mips/include/asm/cpu-features.h +++ b/arch/mips/include/asm/cpu-features.h @@ -487,6 +487,47 @@ # define cpu_has_perf (cpu_data[0].options & MIPS_CPU_PERF) #endif +#if defined(CONFIG_SMP) && defined(__mips_isa_rev) && (__mips_isa_rev >= 6) +/* + * Some systems share FTLB RAMs between threads within a core (siblings in + * kernel parlance). This means that FTLB entries may become invalid at almost + * any point when an entry is evicted due to a sibling thread writing an entry + * to the shared FTLB RAM. + * + * This is only relevant to SMP systems, and the only systems that exhibit this + * property implement MIPSr6 or higher so we constrain support for this to + * kernels that will run on such systems. + */ +# ifndef cpu_has_shared_ftlb_ram +# define cpu_has_shared_ftlb_ram \ + (current_cpu_data.options & MIPS_CPU_SHARED_FTLB_RAM) +# endif + +/* + * Some systems take this a step further & share FTLB entries between siblings. + * This is implemented as TLB writes happening as usual, but if an entry + * written by a sibling exists in the shared FTLB for a translation which would + * otherwise cause a TLB refill exception then the CPU will use the entry + * written by its sibling rather than triggering a refill & writing a matching + * TLB entry for itself. + * + * This is naturally only valid if a TLB entry is known to be suitable for use + * on all siblings in a CPU, and so it only takes effect when MMIDs are in use + * rather than ASIDs or when a TLB entry is marked global. + */ +# ifndef cpu_has_shared_ftlb_entries +# define cpu_has_shared_ftlb_entries \ + (current_cpu_data.options & MIPS_CPU_SHARED_FTLB_ENTRIES) +# endif +#endif /* SMP && __mips_isa_rev >= 6 */ + +#ifndef cpu_has_shared_ftlb_ram +# define cpu_has_shared_ftlb_ram 0 +#endif +#ifndef cpu_has_shared_ftlb_entries +# define cpu_has_shared_ftlb_entries 0 +#endif + /* * Guest capabilities */ |