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From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@intel.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, bp@alien8.de,
	x86@kernel.org, luto@kernel.org, shuah@kernel.org,
	babu.moger@amd.com, dave.kleikamp@oracle.com,
	linuxram@us.ibm.com, bauerman@linux.ibm.com
Subject: Re: [PATCH 0/5] x86/pkeys: PKRU manipulation bug fixes and cleanups
Date: Fri, 28 May 2021 19:19:00 +0200	[thread overview]
Message-ID: <878s3y7p4r.ffs@nanos.tec.linutronix.de> (raw)
In-Reply-To: <4c3bfc27-a542-8e91-7ccf-4be8b1e6c844@intel.com>

On Fri, May 28 2021 at 09:11, Dave Hansen wrote:
> On 5/28/21 8:32 AM, Thomas Gleixner wrote:
> There are also the usual concerns that folks doing user-level context
> switching or other insanity get PKRU context switching for "free" when
> it's XSAVE-managed.  Moving away from that could break them.

Both issues are trivial to solve.

We can have pkru enabled in xcr0 and just do not restore it when
returning to user space (clear the mask bit).

When we restore it in sigrestore via xrstor then we read it via rdpkru
afterwards and update task->thread.pkru.

Thanks,

        tglx


      parent reply	other threads:[~2021-05-28 17:19 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-27 23:51 [PATCH 0/5] x86/pkeys: PKRU manipulation bug fixes and cleanups Dave Hansen
2021-05-27 23:51 ` [PATCH 1/5] x86/pkeys: move read_pkru() and write_pkru() Dave Hansen
2021-05-27 23:51 ` [PATCH 2/5] x86/pkeys: rename write_pkru() Dave Hansen
2021-05-27 23:51 ` [PATCH 3/5] x86/pkeys: skip 'init_pkru' debugfs file creation when pkeys not supported Dave Hansen
2021-05-27 23:51 ` [PATCH 4/5] x86/pkeys: replace PKRU modification infrastructure Dave Hansen
2021-05-28  1:17   ` Mika Penttilä
2021-05-28 17:00   ` Dave Kleikamp
2021-06-01 21:54   ` Babu Moger
2021-06-01 22:43     ` Dave Kleikamp
2021-06-01 22:49       ` Dave Hansen
2021-05-27 23:51 ` [PATCH 5/5] selftests/vm/pkeys: exercise x86 XSAVE init state Dave Hansen
2021-05-28 15:32 ` [PATCH 0/5] x86/pkeys: PKRU manipulation bug fixes and cleanups Thomas Gleixner
2021-05-28 16:11   ` Dave Hansen
2021-05-28 17:13     ` Andy Lutomirski
2021-05-28 17:19       ` Thomas Gleixner
2021-05-28 17:19     ` Thomas Gleixner [this message]

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