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>,
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 V3 4/9] x86/pks: Preserve the PKRS MSR on context switch
Date: Fri, 16 Oct 2020 13:06:36 +0200 [thread overview]
Message-ID: <20201016110636.GL2611@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20201009194258.3207172-5-ira.weiny@intel.com>
On Fri, Oct 09, 2020 at 12:42:53PM -0700, ira.weiny@intel.com wrote:
> @@ -644,6 +663,8 @@ void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
>
> if ((tifp ^ tifn) & _TIF_SLD)
> switch_to_sld(tifn);
> +
> + pks_sched_in();
> }
>
You seem to have lost the comment proposed here:
https://lkml.kernel.org/r/20200717083140.GW10769@hirez.programming.kicks-ass.net
It is useful and important information that the wrmsr normally doesn't
happen.
> diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
> index 3cf8f775f36d..30f65dd3d0c5 100644
> --- a/arch/x86/mm/pkeys.c
> +++ b/arch/x86/mm/pkeys.c
> @@ -229,3 +229,31 @@ u32 update_pkey_val(u32 pk_reg, int pkey, unsigned int flags)
>
> return pk_reg;
> }
> +
> +DEFINE_PER_CPU(u32, pkrs_cache);
> +
> +/**
> + * It should also be noted that the underlying WRMSR(MSR_IA32_PKRS) is not
> + * serializing but still maintains ordering properties similar to WRPKRU.
> + * The current SDM section on PKRS needs updating but should be the same as
> + * that of WRPKRU. So to quote from the WRPKRU text:
> + *
> + * WRPKRU will never execute transiently. Memory accesses
> + * affected by PKRU register will not execute (even transiently)
> + * until all prior executions of WRPKRU have completed execution
> + * and updated the PKRU register.
(whitespace damage; space followed by tabstop)
> + */
> +void write_pkrs(u32 new_pkrs)
> +{
> + u32 *pkrs;
> +
> + if (!static_cpu_has(X86_FEATURE_PKS))
> + return;
> +
> + pkrs = get_cpu_ptr(&pkrs_cache);
> + if (*pkrs != new_pkrs) {
> + *pkrs = new_pkrs;
> + wrmsrl(MSR_IA32_PKRS, new_pkrs);
> + }
> + put_cpu_ptr(pkrs);
> +}
looks familiar that... :-)
next prev parent reply other threads:[~2020-10-16 11:06 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-09 19:42 [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 ira.weiny
2020-10-09 19:42 ` [PATCH RFC V3 1/9] x86/pkeys: Create pkeys_common.h ira.weiny
2020-10-13 17:46 ` Dave Hansen
2020-10-13 19:44 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 2/9] x86/fpu: Refactor arch_set_user_pkey_access() for PKS support ira.weiny
2020-10-13 17:50 ` Dave Hansen
2020-10-13 23:56 ` Ira Weiny
2020-10-16 10:57 ` Peter Zijlstra
2020-10-17 3:32 ` Ira Weiny
2020-10-19 9:35 ` Peter Zijlstra
2020-10-09 19:42 ` [PATCH RFC V3 3/9] x86/pks: Enable Protection Keys Supervisor (PKS) ira.weiny
2020-10-13 18:23 ` Dave Hansen
2020-10-14 2:08 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 4/9] x86/pks: Preserve the PKRS MSR on context switch ira.weiny
2020-10-13 18:31 ` Dave Hansen
2020-10-14 22:36 ` Ira Weiny
2020-10-16 11:12 ` Peter Zijlstra
2020-10-17 5:14 ` Ira Weiny
2020-10-19 9:37 ` Peter Zijlstra
2020-10-19 18:48 ` Ira Weiny
2020-10-16 11:06 ` Peter Zijlstra [this message]
2020-10-17 5:37 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 5/9] x86/pks: Add PKS kernel API ira.weiny
2020-10-13 18:43 ` Dave Hansen
2020-10-15 1:08 ` Ira Weiny
2020-10-16 11:07 ` Peter Zijlstra
2020-10-17 5:42 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 6/9] x86/entry: Pass irqentry_state_t by reference ira.weiny
2020-10-16 11:45 ` Peter Zijlstra
2020-10-16 12:55 ` Thomas Gleixner
2020-10-19 5:37 ` Ira Weiny
2020-10-19 9:32 ` Thomas Gleixner
2020-10-19 20:26 ` Ira Weiny
2020-10-19 21:12 ` Thomas Gleixner
2020-10-20 14:10 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 7/9] x86/entry: Preserve PKRS MSR across exceptions ira.weiny
2020-10-13 18:52 ` Dave Hansen
2020-10-15 3:46 ` Ira Weiny
2020-10-15 4:06 ` Dave Hansen
2020-10-15 4:18 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 8/9] x86/fault: Report the PKRS state on fault ira.weiny
2020-10-13 18:56 ` Dave Hansen
2020-10-15 4:13 ` Ira Weiny
2020-10-09 19:42 ` [PATCH RFC V3 9/9] x86/pks: Add PKS test code ira.weiny
2020-10-13 19:02 ` Dave Hansen
2020-10-15 4:46 ` Ira Weiny
2020-10-09 20:18 ` [PATCH RFC V3 0/9] PKS: Add Protection Keys Supervisor (PKS) support RFC v3 Ira Weiny
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