From: Dan Williams <dan.j.williams@intel.com>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, X86 ML <x86@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/5] generic/pgtable: Introduce set_pte_safe()
Date: Mon, 3 Dec 2018 09:57:09 -0800 [thread overview]
Message-ID: <CAPcyv4gLA_UryDZzdtAi-T=2x8io4V_2BwX_qTF7KS8Ff1Kb3A@mail.gmail.com> (raw)
In-Reply-To: <4bc8cab6-4e1a-c3b9-0023-3ecde932cc70@intel.com>
On Mon, Dec 3, 2018 at 9:53 AM Dave Hansen <dave.hansen@intel.com> wrote:
>
> On 11/30/18 4:35 PM, Dan Williams wrote:
> > +/*
> > + * The _safe versions of set_{pte,pmd,pud,p4d,pgd} validate that the
> > + * entry was not populated previously. I.e. for cases where a flush-tlb
> > + * is elided, double-check that there is no stale mapping to shoot down.
> > + */
>
> Functionally these look great to me.
>
> The only thing I'd suggest is to make the comment more about when to use
> these, instead of what they do:
>
> Use the set_p*_safe() version when confident that *no*
> TLB flush will be required as a result of the "set", such
> as setting non-present entries or when possibly superfluously
> re-setting an entry.
The second sentence was meant to be a "why", but yes, it's entirely too subtle.
next prev parent reply other threads:[~2018-12-03 17:57 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-01 0:35 [PATCH v2 0/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init() Dan Williams
2018-12-01 0:35 ` Dan Williams
2018-12-01 0:35 ` [PATCH v2 1/5] generic/pgtable: Make {pmd, pud}_same() unconditionally available Dan Williams
2018-12-01 0:35 ` [PATCH v2 2/5] generic/pgtable: Introduce {p4d,pgd}_same() Dan Williams
2018-12-01 0:35 ` [PATCH v2 3/5] generic/pgtable: Introduce set_pte_safe() Dan Williams
2018-12-03 17:53 ` Dave Hansen
2018-12-03 17:57 ` Dan Williams [this message]
2018-12-01 0:35 ` [PATCH v2 4/5] x86/mm: Validate kernel_physical_mapping_init() pte population Dan Williams
2018-12-01 0:35 ` [PATCH v2 5/5] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init() Dan Williams
2018-12-01 10:27 ` Peter Zijlstra
2018-12-02 6:43 ` Sasha Levin
2018-12-02 17:04 ` Dan Williams
2018-12-03 17:18 ` Dave Hansen
2018-12-01 10:28 ` [PATCH v2 0/5] " Peter Zijlstra
2018-12-01 17:49 ` Dan Williams
2018-12-03 9:21 ` Kirill A. Shutemov
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