From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7CEEEC4332F for ; Fri, 1 Oct 2021 08:19:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 53F8961A57 for ; Fri, 1 Oct 2021 08:19:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231327AbhJAIUv (ORCPT ); Fri, 1 Oct 2021 04:20:51 -0400 Received: from jabberwock.ucw.cz ([46.255.230.98]:48808 "EHLO jabberwock.ucw.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231161AbhJAIUt (ORCPT ); Fri, 1 Oct 2021 04:20:49 -0400 Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id 6A8331C0B80; Fri, 1 Oct 2021 10:19:04 +0200 (CEST) Date: Fri, 1 Oct 2021 10:19:03 +0200 From: Pavel Machek To: Sohil Mehta Cc: x86@kernel.org, Tony Luck , Dave Hansen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H . Peter Anvin" , Andy Lutomirski , Jens Axboe , Christian Brauner , Peter Zijlstra , Shuah Khan , Arnd Bergmann , Jonathan Corbet , Ashok Raj , Jacob Pan , Gayatri Kammela , Zeng Guang , Dan Williams , Randy E Witt , Ravi V Shankar , Ramesh Thomas , linux-api@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [RFC PATCH 00/13] x86 User Interrupts support Message-ID: <20211001081903.GA18962@amd> References: <20210913200132.3396598-1-sohil.mehta@intel.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="WIyZ46R2i8wDzkSu" Content-Disposition: inline In-Reply-To: <20210913200132.3396598-1-sohil.mehta@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org --WIyZ46R2i8wDzkSu Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > Instructions > ------------ > senduipi - send a user IPI to a target task based on the UITT ind= ex. >=20 > clui - Mask user interrupts by clearing UIF (User Interrupt Flag). >=20 > stui - Unmask user interrupts by setting UIF. >=20 > testui - Test current value of UIF. >=20 > uiret - return from a user interrupt handler. Are other CPU vendors allowed to implement compatible instructions? If not, we should probably have VDSO entries so kernel can abstract differences between CPUs. > Untrusted processes > ------------------- > The current implementation expects only trusted and cooperating processes= to > communicate using user interrupts. Coordination is expected between proce= sses > for a connection teardown. In situations where coordination doesn't happen > (say, due to abrupt process exit), the kernel would end up keeping shared > resources (like UPID) allocated to avoid faults. Keeping resources allocated after process exit is a no-no. Best regards, Pavel --=20 http://www.livejournal.com/~pavelmachek --WIyZ46R2i8wDzkSu Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAmFWxHcACgkQMOfwapXb+vJxvwCfT//NrkD3M2U42/1DYnf87idv hk0AoJONzceoKozw6x+bt0MVUuWLOpzR =eUmo -----END PGP SIGNATURE----- --WIyZ46R2i8wDzkSu--