From: Peter Zijlstra <peterz@infradead.org>
To: Alison Schofield <alison.schofield@intel.com>
Cc: dhowells@redhat.com, tglx@linutronix.de, jmorris@namei.org,
mingo@redhat.com, hpa@zytor.com, bp@alien8.de, luto@kernel.org,
kirill.shutemov@linux.intel.com, dave.hansen@intel.com,
kai.huang@intel.com, jun.nakajima@intel.com,
dan.j.williams@intel.com, jarkko.sakkinen@intel.com,
keyrings@vger.kernel.org, linux-security-module@vger.kernel.org,
linux-mm@kvack.org, x86@kernel.org
Subject: Re: [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis
Date: Wed, 5 Dec 2018 10:10:29 +0100 [thread overview]
Message-ID: <20181205091029.GB4234@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181205054353.GE18596@alison-desk.jf.intel.com>
On Tue, Dec 04, 2018 at 09:43:53PM -0800, Alison Schofield wrote:
> On Tue, Dec 04, 2018 at 10:21:45AM +0100, Peter Zijlstra wrote:
> > On Mon, Dec 03, 2018 at 11:39:58PM -0800, Alison Schofield wrote:
> >
> > > +static int mktme_build_leadcpus_mask(void)
> > > +{
> > > + int online_cpu, mktme_cpu;
> > > + int online_pkgid, mktme_pkgid = -1;
> > > +
> > > + if (!zalloc_cpumask_var(&mktme_leadcpus, GFP_KERNEL))
> > > + return -ENOMEM;
> > > +
> > > + for_each_online_cpu(online_cpu) {
> > > + online_pkgid = topology_physical_package_id(online_cpu);
> > > +
> > > + for_each_cpu(mktme_cpu, mktme_leadcpus) {
> > > + mktme_pkgid = topology_physical_package_id(mktme_cpu);
> > > + if (mktme_pkgid == online_pkgid)
> > > + break;
> > > + }
> > > + if (mktme_pkgid != online_pkgid)
> > > + cpumask_set_cpu(online_cpu, mktme_leadcpus);
> >
> > Do you really need LOCK prefixed bit set here?
> No. Changed to __cpumask_set_cpu(). Will check for other instances
> where I can skip LOCK prefix.
>
> > How is that serialized and kept relevant in the face of hotplug?
> mktme_leadcpus is updated on hotplug startup and teardowns.
Not in this patch it is not. That is added in a subsequent patch, which
means that during bisection hotplug is utterly wrecked if you happen to
land between these patches, that is bad.
> > Also, do you really need O(n^2) to find the first occurence of a value
> > in an array?
> How about this O(n)?
>
> unsigned long *pkg_map;
> int cpu, pkgid;
>
> if (!zalloc_cpumask_var(&mktme_leadcpus, GFP_KERNEL))
> return -ENOMEM;
>
> pkg_map = bitmap_zalloc(topology_max_packages(), GFP_KERNEL);
> if (!pkg_map) {
> free_cpumask_var(mktme_leadcpus);
> return -ENOMEM;
> }
> for_each_online_cpu(cpu) {
> pkgid = topology_physical_package_id(cpu);
> if (!test_and_set_bit(pkgid, pkg_map))
You again don't need that LOCK prefix here.
__test_and_set_bit() :-)
> __cpumask_set_cpu(cpu, mktme_leadcpus);
> }
Right.
next prev parent reply other threads:[~2018-12-05 9:10 UTC|newest]
Thread overview: 91+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-04 7:39 [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Alison Schofield
2018-12-04 7:39 ` [RFC v2 01/13] x86/mktme: Document the MKTME APIs Alison Schofield
2018-12-05 18:11 ` Andy Lutomirski
2018-12-05 19:22 ` Alison Schofield
2018-12-05 23:35 ` Andy Lutomirski
2018-12-06 8:04 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 02/13] mm: Generalize the mprotect implementation to support extensions Alison Schofield
2018-12-06 8:08 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 03/13] syscall/x86: Wire up a new system call for memory encryption keys Alison Schofield
2018-12-04 7:39 ` [RFC v2 04/13] x86/mm: Add helper functions for MKTME " Alison Schofield
2018-12-04 9:14 ` Peter Zijlstra
2018-12-05 5:49 ` Alison Schofield
2018-12-04 15:35 ` Andy Lutomirski
2018-12-05 5:52 ` Alison Schofield
2018-12-06 8:31 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 05/13] x86/mm: Set KeyIDs in encrypted VMAs Alison Schofield
2018-12-06 8:37 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 06/13] mm: Add the encrypt_mprotect() system call Alison Schofield
2018-12-06 8:38 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 07/13] x86/mm: Add helpers for reference counting encrypted VMAs Alison Schofield
2018-12-04 8:58 ` Peter Zijlstra
2018-12-05 5:28 ` Alison Schofield
2018-12-04 7:39 ` [RFC v2 08/13] mm: Use reference counting for " Alison Schofield
2018-12-04 7:39 ` [RFC v2 09/13] mm: Restrict memory encryption to anonymous VMA's Alison Schofield
2018-12-04 9:10 ` Peter Zijlstra
2018-12-05 5:30 ` Alison Schofield
2018-12-05 9:07 ` Peter Zijlstra
2018-12-04 7:39 ` [RFC v2 10/13] keys/mktme: Add the MKTME Key Service type for memory encryption Alison Schofield
2018-12-06 8:51 ` Sakkinen, Jarkko
2018-12-06 8:54 ` Sakkinen, Jarkko
2018-12-06 15:11 ` Dave Hansen
2018-12-06 22:56 ` Sakkinen, Jarkko
2018-12-04 7:39 ` [RFC v2 11/13] keys/mktme: Program memory encryption keys on a system wide basis Alison Schofield
2018-12-04 9:21 ` Peter Zijlstra
2018-12-04 9:50 ` Kirill A. Shutemov
2018-12-05 5:44 ` Alison Schofield
2018-12-05 5:43 ` Alison Schofield
2018-12-05 9:10 ` Peter Zijlstra [this message]
2018-12-05 17:26 ` Alison Schofield
2018-12-04 7:39 ` [RFC v2 12/13] keys/mktme: Save MKTME data if kernel cmdline parameter allows Alison Schofield
2018-12-04 9:22 ` Peter Zijlstra
2018-12-07 2:14 ` Huang, Kai
2018-12-07 3:42 ` Alison Schofield
2018-12-07 6:39 ` Jarkko Sakkinen
2018-12-07 6:45 ` Jarkko Sakkinen
2018-12-07 11:47 ` Kirill A. Shutemov
2018-12-04 7:40 ` [RFC v2 13/13] keys/mktme: Support CPU Hotplug for MKTME keys Alison Schofield
2018-12-04 9:28 ` Peter Zijlstra
2018-12-05 5:32 ` Alison Schofield
2018-12-04 9:31 ` Peter Zijlstra
2018-12-05 5:36 ` Alison Schofield
2018-12-04 9:25 ` [RFC v2 00/13] Multi-Key Total Memory Encryption API (MKTME) Peter Zijlstra
2018-12-04 9:46 ` Kirill A. Shutemov
2018-12-05 20:32 ` Sakkinen, Jarkko
2018-12-06 11:22 ` Kirill A. Shutemov
2018-12-06 14:59 ` Dave Hansen
2018-12-07 10:12 ` Huang, Kai
2018-12-06 21:23 ` Sakkinen, Jarkko
2018-12-07 11:54 ` Kirill A. Shutemov
2018-12-04 19:19 ` Andy Lutomirski
2018-12-04 20:00 ` Andy Lutomirski
2018-12-04 20:32 ` Dave Hansen
2018-12-05 22:19 ` Sakkinen, Jarkko
2018-12-07 2:05 ` Huang, Kai
2018-12-07 6:48 ` Jarkko Sakkinen
2018-12-07 11:57 ` Kirill A. Shutemov
2018-12-07 21:59 ` Sakkinen, Jarkko
2018-12-07 23:45 ` Sakkinen, Jarkko
2018-12-07 23:48 ` Andy Lutomirski
2018-12-08 1:33 ` Huang, Kai
2018-12-08 3:53 ` Sakkinen, Jarkko
2018-12-12 15:31 ` Sakkinen, Jarkko
2018-12-12 16:29 ` Andy Lutomirski
2018-12-12 16:43 ` Sakkinen, Jarkko
2018-12-12 23:27 ` Huang, Kai
2018-12-13 5:49 ` Sakkinen, Jarkko
2018-12-13 5:52 ` Sakkinen, Jarkko
2018-12-12 23:24 ` Huang, Kai
2018-12-07 23:35 ` Eric Rannaud
2018-12-05 23:49 ` Dave Hansen
2018-12-06 1:09 ` Andy Lutomirski
2018-12-06 1:25 ` Dan Williams
2018-12-06 15:39 ` Dave Hansen
2018-12-06 19:10 ` Andy Lutomirski
2018-12-06 19:31 ` Dave Hansen
2018-12-07 1:55 ` Huang, Kai
2018-12-07 4:23 ` Dave Hansen
2018-12-07 23:53 ` Andy Lutomirski
2018-12-08 1:11 ` Dave Hansen
2018-12-08 2:07 ` Huang, Kai
2018-12-05 20:30 ` Sakkinen, Jarkko
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