From: Peter Zijlstra <peterz@infradead.org> To: ira.weiny@intel.com Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>, x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V2 04/17] x86/pks: Preserve the PKRS MSR on context switch Date: Fri, 17 Jul 2020 10:31:40 +0200 [thread overview] Message-ID: <20200717083140.GW10769@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20200717072056.73134-5-ira.weiny@intel.com> On Fri, Jul 17, 2020 at 12:20:43AM -0700, ira.weiny@intel.com wrote: > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index f362ce0d5ac0..d69250a7c1bf 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -42,6 +42,7 @@ > #include <asm/spec-ctrl.h> > #include <asm/io_bitmap.h> > #include <asm/proto.h> > +#include <asm/pkeys_internal.h> > > #include "process.h" > > @@ -184,6 +185,36 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, > return ret; > } > > +/* > + * NOTE: We wrap pks_init_task() and pks_sched_in() with > + * CONFIG_ARCH_HAS_SUPERVISOR_PKEYS because using IS_ENABLED() fails > + * due to the lack of task_struct->saved_pkrs in this configuration. > + * Furthermore, we place them here because of the complexity introduced by > + * header conflicts introduced to get the task_struct definition in the pkeys > + * headers. > + */ I don't see anything much useful in that comment. > +#ifdef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS > +DECLARE_PER_CPU(u32, pkrs_cache); > +static inline void pks_init_task(struct task_struct *tsk) > +{ > + /* New tasks get the most restrictive PKRS value */ > + tsk->thread.saved_pkrs = INIT_PKRS_VALUE; > +} > +static inline void pks_sched_in(void) > +{ > + u64 current_pkrs = current->thread.saved_pkrs; > + > + /* Only update the MSR when current's pkrs is different from the MSR. */ > + if (this_cpu_read(pkrs_cache) == current_pkrs) > + return; > + > + write_pkrs(current_pkrs); Should we write that like: /* * PKRS is only temporarily changed during specific code paths. * Only a preemption during these windows away from the default * value would require updating the MSR. */ if (unlikely(this_cpu_read(pkrs_cache) != current_pkrs)) write_pkrs(current_pkrs); ? > +} > +#else > +static inline void pks_init_task(struct task_struct *tsk) { } > +static inline void pks_sched_in(void) { } > +#endif _______________________________________________ Linux-nvdimm mailing list -- linux-nvdimm@lists.01.org To unsubscribe send an email to linux-nvdimm-leave@lists.01.org
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org> To: ira.weiny@intel.com Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>, Fenghua Yu <fenghua.yu@intel.com>, x86@kernel.org, Dave Hansen <dave.hansen@linux.intel.com>, Dan Williams <dan.j.williams@intel.com>, Vishal Verma <vishal.l.verma@intel.com>, Andrew Morton <akpm@linux-foundation.org>, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V2 04/17] x86/pks: Preserve the PKRS MSR on context switch Date: Fri, 17 Jul 2020 10:31:40 +0200 [thread overview] Message-ID: <20200717083140.GW10769@hirez.programming.kicks-ass.net> (raw) In-Reply-To: <20200717072056.73134-5-ira.weiny@intel.com> On Fri, Jul 17, 2020 at 12:20:43AM -0700, ira.weiny@intel.com wrote: > diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c > index f362ce0d5ac0..d69250a7c1bf 100644 > --- a/arch/x86/kernel/process.c > +++ b/arch/x86/kernel/process.c > @@ -42,6 +42,7 @@ > #include <asm/spec-ctrl.h> > #include <asm/io_bitmap.h> > #include <asm/proto.h> > +#include <asm/pkeys_internal.h> > > #include "process.h" > > @@ -184,6 +185,36 @@ int copy_thread_tls(unsigned long clone_flags, unsigned long sp, > return ret; > } > > +/* > + * NOTE: We wrap pks_init_task() and pks_sched_in() with > + * CONFIG_ARCH_HAS_SUPERVISOR_PKEYS because using IS_ENABLED() fails > + * due to the lack of task_struct->saved_pkrs in this configuration. > + * Furthermore, we place them here because of the complexity introduced by > + * header conflicts introduced to get the task_struct definition in the pkeys > + * headers. > + */ I don't see anything much useful in that comment. > +#ifdef CONFIG_ARCH_HAS_SUPERVISOR_PKEYS > +DECLARE_PER_CPU(u32, pkrs_cache); > +static inline void pks_init_task(struct task_struct *tsk) > +{ > + /* New tasks get the most restrictive PKRS value */ > + tsk->thread.saved_pkrs = INIT_PKRS_VALUE; > +} > +static inline void pks_sched_in(void) > +{ > + u64 current_pkrs = current->thread.saved_pkrs; > + > + /* Only update the MSR when current's pkrs is different from the MSR. */ > + if (this_cpu_read(pkrs_cache) == current_pkrs) > + return; > + > + write_pkrs(current_pkrs); Should we write that like: /* * PKRS is only temporarily changed during specific code paths. * Only a preemption during these windows away from the default * value would require updating the MSR. */ if (unlikely(this_cpu_read(pkrs_cache) != current_pkrs)) write_pkrs(current_pkrs); ? > +} > +#else > +static inline void pks_init_task(struct task_struct *tsk) { } > +static inline void pks_sched_in(void) { } > +#endif
next prev parent reply other threads:[~2020-07-17 8:32 UTC|newest] Thread overview: 157+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-07-17 7:20 [PATCH RFC V2 00/17] PKS: Add Protection Keys Supervisor (PKS) support ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 01/17] x86/pkeys: Create pkeys_internal.h ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 02/17] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 8:54 ` Peter Zijlstra 2020-07-17 8:54 ` Peter Zijlstra 2020-07-17 20:52 ` Ira Weiny 2020-07-17 20:52 ` Ira Weiny 2020-07-20 9:14 ` Peter Zijlstra 2020-07-20 9:14 ` Peter Zijlstra 2020-07-17 22:36 ` Dave Hansen 2020-07-17 22:36 ` Dave Hansen 2020-07-20 9:13 ` Peter Zijlstra 2020-07-20 9:13 ` Peter Zijlstra 2020-07-17 7:20 ` [PATCH RFC V2 03/17] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 04/17] x86/pks: Preserve the PKRS MSR on context switch ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 8:31 ` Peter Zijlstra [this message] 2020-07-17 8:31 ` Peter Zijlstra 2020-07-17 21:39 ` Ira Weiny 2020-07-17 21:39 ` Ira Weiny 2020-07-17 8:59 ` Peter Zijlstra 2020-07-17 8:59 ` Peter Zijlstra 2020-07-17 22:34 ` Ira Weiny 2020-07-17 22:34 ` Ira Weiny 2020-07-20 9:15 ` Peter Zijlstra 2020-07-20 9:15 ` Peter Zijlstra 2020-07-20 18:35 ` Ira Weiny 2020-07-20 18:35 ` Ira Weiny 2020-07-17 7:20 ` [PATCH RFC V2 05/17] x86/pks: Add PKS kernel API ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 06/17] x86/pks: Add a debugfs file for allocated PKS keys ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 07/17] Documentation/pkeys: Update documentation for kernel pkeys ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 08/17] x86/pks: Add PKS Test code ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 09/17] memremap: Convert devmap static branch to {inc,dec} ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 10/17] fs/dax: Remove unused size parameter ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 11/17] drivers/dax: Expand lock scope to cover the use of addresses ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 12/17] memremap: Add zone device access protection ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 9:10 ` Peter Zijlstra 2020-07-17 9:10 ` Peter Zijlstra 2020-07-18 5:06 ` Ira Weiny 2020-07-18 5:06 ` Ira Weiny 2020-07-20 9:16 ` Peter Zijlstra 2020-07-20 9:16 ` Peter Zijlstra 2020-07-17 9:17 ` Peter Zijlstra 2020-07-17 9:17 ` Peter Zijlstra 2020-07-18 5:51 ` Ira Weiny 2020-07-18 5:51 ` Ira Weiny 2020-07-17 9:20 ` Peter Zijlstra 2020-07-17 9:20 ` Peter Zijlstra 2020-07-17 7:20 ` [PATCH RFC V2 13/17] kmap: Add stray write protection for device pages ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 9:21 ` Peter Zijlstra 2020-07-17 9:21 ` Peter Zijlstra 2020-07-19 4:13 ` Ira Weiny 2020-07-19 4:13 ` Ira Weiny 2020-07-20 9:17 ` Peter Zijlstra 2020-07-20 9:17 ` Peter Zijlstra 2020-07-21 16:31 ` Ira Weiny 2020-07-21 16:31 ` Ira Weiny 2020-07-17 7:20 ` [PATCH RFC V2 14/17] dax: Stray write protection for dax_direct_access() ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 9:22 ` Peter Zijlstra 2020-07-17 9:22 ` Peter Zijlstra 2020-07-19 4:41 ` Ira Weiny 2020-07-19 4:41 ` Ira Weiny 2020-07-17 7:20 ` [PATCH RFC V2 15/17] nvdimm/pmem: Stray write protection for pmem->virt_addr ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 7:20 ` [PATCH RFC V2 16/17] [dax|pmem]: Enable stray write protection ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 9:25 ` Peter Zijlstra 2020-07-17 9:25 ` Peter Zijlstra 2020-07-17 7:20 ` [PATCH RFC V2 17/17] x86/entry: Preserve PKRS MSR across exceptions ira.weiny 2020-07-17 7:20 ` ira.weiny 2020-07-17 9:30 ` Peter Zijlstra 2020-07-17 9:30 ` Peter Zijlstra 2020-07-21 18:01 ` Ira Weiny 2020-07-21 18:01 ` Ira Weiny 2020-07-21 19:11 ` Peter Zijlstra 2020-07-21 19:11 ` Peter Zijlstra 2020-07-17 9:34 ` Peter Zijlstra 2020-07-17 9:34 ` Peter Zijlstra 2020-07-17 10:06 ` Peter Zijlstra 2020-07-17 10:06 ` Peter Zijlstra 2020-07-22 5:27 ` Ira Weiny 2020-07-22 5:27 ` Ira Weiny 2020-07-22 9:48 ` Peter Zijlstra 2020-07-22 9:48 ` Peter Zijlstra 2020-07-22 21:24 ` Ira Weiny 2020-07-22 21:24 ` Ira Weiny 2020-07-23 20:08 ` Thomas Gleixner 2020-07-23 20:08 ` Thomas Gleixner 2020-07-23 20:15 ` Thomas Gleixner 2020-07-23 20:15 ` Thomas Gleixner 2020-07-24 17:23 ` Ira Weiny 2020-07-24 17:23 ` Ira Weiny 2020-07-24 17:29 ` Andy Lutomirski 2020-07-24 17:29 ` Andy Lutomirski 2020-07-24 19:43 ` Ira Weiny 2020-07-24 19:43 ` Ira Weiny 2020-07-22 16:21 ` Andy Lutomirski 2020-07-22 16:21 ` Andy Lutomirski 2020-07-22 16:21 ` Andy Lutomirski 2020-07-23 16:18 ` Fenghua Yu 2020-07-23 16:18 ` Fenghua Yu 2020-07-23 16:18 ` Fenghua Yu 2020-07-23 16:23 ` Dave Hansen 2020-07-23 16:23 ` Dave Hansen 2020-07-23 16:23 ` Dave Hansen 2020-07-23 16:52 ` Fenghua Yu 2020-07-23 16:52 ` Fenghua Yu 2020-07-23 16:52 ` Fenghua Yu 2020-07-23 17:08 ` Andy Lutomirski 2020-07-23 17:08 ` Andy Lutomirski 2020-07-23 17:08 ` Andy Lutomirski 2020-07-23 17:30 ` Dave Hansen 2020-07-23 17:30 ` Dave Hansen 2020-07-23 17:30 ` Dave Hansen 2020-07-23 20:23 ` Thomas Gleixner 2020-07-23 20:23 ` Thomas Gleixner 2020-07-23 20:23 ` Thomas Gleixner 2020-07-23 20:22 ` Thomas Gleixner 2020-07-23 20:22 ` Thomas Gleixner 2020-07-23 20:22 ` Thomas Gleixner 2020-07-23 21:30 ` Andy Lutomirski 2020-07-23 21:30 ` Andy Lutomirski 2020-07-23 21:30 ` Andy Lutomirski 2020-07-23 22:14 ` Thomas Gleixner 2020-07-23 22:14 ` Thomas Gleixner 2020-07-23 22:14 ` Thomas Gleixner 2020-07-23 19:53 ` Thomas Gleixner 2020-07-23 19:53 ` Thomas Gleixner 2020-07-23 22:04 ` Ira Weiny 2020-07-23 22:04 ` Ira Weiny 2020-07-23 23:41 ` Thomas Gleixner 2020-07-23 23:41 ` Thomas Gleixner 2020-07-24 21:24 ` Thomas Gleixner 2020-07-24 21:24 ` Thomas Gleixner 2020-07-24 21:31 ` Thomas Gleixner 2020-07-24 21:31 ` Thomas Gleixner 2020-07-25 0:09 ` Andy Lutomirski 2020-07-25 0:09 ` Andy Lutomirski 2020-07-25 0:09 ` Andy Lutomirski 2020-07-27 20:59 ` Ira Weiny 2020-07-27 20:59 ` Ira Weiny 2020-07-24 22:19 ` [PATCH RFC V2 00/17] PKS: Add Protection Keys Supervisor (PKS) support Kees Cook 2020-07-24 22:19 ` Kees Cook
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=20200717083140.GW10769@hirez.programming.kicks-ass.net \ --to=peterz@infradead.org \ --cc=akpm@linux-foundation.org \ --cc=bp@alien8.de \ --cc=dave.hansen@linux.intel.com \ --cc=fenghua.yu@intel.com \ --cc=ira.weiny@intel.com \ --cc=linux-doc@vger.kernel.org \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-kselftest@vger.kernel.org \ --cc=linux-mm@kvack.org \ --cc=linux-nvdimm@lists.01.org \ --cc=luto@kernel.org \ --cc=mingo@redhat.com \ --cc=tglx@linutronix.de \ --cc=x86@kernel.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.