From: Paul Burton <paul.burton@imgtec.com> To: <linux-mips@linux-mips.org> Cc: Paul Burton <paul.burton@imgtec.com>, Ralf Baechle <ralf@linux-mips.org> Subject: [PATCH 1/6] MIPS: Add CPU shared FTLB feature detection Date: Fri, 2 Jun 2017 15:38:01 -0700 [thread overview] Message-ID: <20170602223806.5078-2-paul.burton@imgtec.com> (raw) In-Reply-To: <20170602223806.5078-1-paul.burton@imgtec.com> 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: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org --- This depends upon my "MIPS: Probe the I6500 CPU" patch being applied first in order to make use of CPU_I6500. arch/mips/include/asm/cpu-features.h | 41 ++++++++++++++++++++++++++++++++++++ arch/mips/include/asm/cpu.h | 4 ++++ arch/mips/kernel/cpu-probe.c | 11 ++++++++++ 3 files changed, 56 insertions(+) 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 */ diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h index 3069359b0120..9bc820c4e1ed 100644 --- a/arch/mips/include/asm/cpu.h +++ b/arch/mips/include/asm/cpu.h @@ -417,6 +417,10 @@ enum cpu_type_enum { #define MIPS_CPU_GUESTID MBIT_ULL(51) /* CPU uses VZ ASE GuestID feature */ #define MIPS_CPU_DRG MBIT_ULL(52) /* CPU has VZ Direct Root to Guest (DRG) */ #define MIPS_CPU_UFR MBIT_ULL(53) /* CPU supports User mode FR switching */ +#define MIPS_CPU_SHARED_FTLB_RAM \ + MBIT_ULL(54) /* CPU shares FTLB RAM with another */ +#define MIPS_CPU_SHARED_FTLB_ENTRIES \ + MBIT_ULL(55) /* CPU shares FTLB entries with another */ /* * CPU ASE encodings diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index 353ade2c130a..8135002116df 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -1653,6 +1653,17 @@ static inline void cpu_probe_mips(struct cpuinfo_mips *c, unsigned int cpu) decode_configs(c); spram_config(); + + switch (__get_cpu_type(c->cputype)) { + case CPU_I6500: + c->options |= MIPS_CPU_SHARED_FTLB_ENTRIES; + /* fall-through */ + case CPU_I6400: + c->options |= MIPS_CPU_SHARED_FTLB_RAM; + /* fall-through */ + default: + break; + } } static inline void cpu_probe_alchemy(struct cpuinfo_mips *c, unsigned int cpu) -- 2.13.0
WARNING: multiple messages have this Message-ID (diff)
From: Paul Burton <paul.burton@imgtec.com> To: linux-mips@linux-mips.org Cc: Paul Burton <paul.burton@imgtec.com>, Ralf Baechle <ralf@linux-mips.org> Subject: [PATCH 1/6] MIPS: Add CPU shared FTLB feature detection Date: Fri, 2 Jun 2017 15:38:01 -0700 [thread overview] Message-ID: <20170602223806.5078-2-paul.burton@imgtec.com> (raw) Message-ID: <20170602223801.OHEGKp-Vv3L3W1f9HvZuTPnyouymodRLkF_gGWK_B6A@z> (raw) In-Reply-To: <20170602223806.5078-1-paul.burton@imgtec.com> 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: Ralf Baechle <ralf@linux-mips.org> Cc: linux-mips@linux-mips.org --- This depends upon my "MIPS: Probe the I6500 CPU" patch being applied first in order to make use of CPU_I6500. arch/mips/include/asm/cpu-features.h | 41 ++++++++++++++++++++++++++++++++++++ arch/mips/include/asm/cpu.h | 4 ++++ arch/mips/kernel/cpu-probe.c | 11 ++++++++++ 3 files changed, 56 insertions(+) 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 */ diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h index 3069359b0120..9bc820c4e1ed 100644 --- a/arch/mips/include/asm/cpu.h +++ b/arch/mips/include/asm/cpu.h @@ -417,6 +417,10 @@ enum cpu_type_enum { #define MIPS_CPU_GUESTID MBIT_ULL(51) /* CPU uses VZ ASE GuestID feature */ #define MIPS_CPU_DRG MBIT_ULL(52) /* CPU has VZ Direct Root to Guest (DRG) */ #define MIPS_CPU_UFR MBIT_ULL(53) /* CPU supports User mode FR switching */ +#define MIPS_CPU_SHARED_FTLB_RAM \ + MBIT_ULL(54) /* CPU shares FTLB RAM with another */ +#define MIPS_CPU_SHARED_FTLB_ENTRIES \ + MBIT_ULL(55) /* CPU shares FTLB entries with another */ /* * CPU ASE encodings diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c index 353ade2c130a..8135002116df 100644 --- a/arch/mips/kernel/cpu-probe.c +++ b/arch/mips/kernel/cpu-probe.c @@ -1653,6 +1653,17 @@ static inline void cpu_probe_mips(struct cpuinfo_mips *c, unsigned int cpu) decode_configs(c); spram_config(); + + switch (__get_cpu_type(c->cputype)) { + case CPU_I6500: + c->options |= MIPS_CPU_SHARED_FTLB_ENTRIES; + /* fall-through */ + case CPU_I6400: + c->options |= MIPS_CPU_SHARED_FTLB_RAM; + /* fall-through */ + default: + break; + } } static inline void cpu_probe_alchemy(struct cpuinfo_mips *c, unsigned int cpu) -- 2.13.0
next prev parent reply other threads:[~2017-06-02 22:39 UTC|newest] Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-06-02 22:38 [PATCH 0/6] MIPS: TLB exception handler fixes & optimisation Paul Burton 2017-06-02 22:38 ` Paul Burton 2017-06-02 22:38 ` Paul Burton [this message] 2017-06-02 22:38 ` [PATCH 1/6] MIPS: Add CPU shared FTLB feature detection Paul Burton 2017-06-02 22:38 ` [PATCH 2/6] MIPS: Handle tlbex-tlbp race condition Paul Burton 2017-06-02 22:38 ` Paul Burton 2017-06-02 22:38 ` [PATCH 3/6] MIPS: Allow storing pgd in C0_CONTEXT for MIPSr6 Paul Burton 2017-06-02 22:38 ` Paul Burton 2017-06-02 22:38 ` [PATCH 4/6] MIPS: Use current_cpu_type() in m4kc_tlbp_war() Paul Burton 2017-06-02 22:38 ` Paul Burton 2017-06-02 22:38 ` [PATCH 5/6] MIPS: tlbex: Use ErrorEPC as scratch when KScratch isn't available Paul Burton 2017-06-02 22:38 ` Paul Burton 2017-06-15 17:27 ` Maciej W. Rozycki 2017-06-15 17:27 ` Maciej W. Rozycki 2017-06-28 15:25 ` Ralf Baechle 2017-06-29 16:39 ` Maciej W. Rozycki 2017-06-29 16:39 ` Maciej W. Rozycki 2017-06-02 22:38 ` [PATCH 6/6] MIPS: tlbex: Remove struct work_registers Paul Burton 2017-06-02 22:38 ` Paul Burton
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20170602223806.5078-2-paul.burton@imgtec.com \ --to=paul.burton@imgtec.com \ --cc=linux-mips@linux-mips.org \ --cc=ralf@linux-mips.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.