From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: Notes on stubdoms and latency on ARM Date: Tue, 20 Jun 2017 12:00:46 +0200 Message-ID: <1497952846.7405.19.camel@citrix.com> References: <8c63069d-c909-e82c-ecba-5451f822a5cc@citrix.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============2027627516704388183==" Return-path: In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xen.org Sender: "Xen-devel" To: Volodymyr Babchuk , George Dunlap Cc: Artem_Mygaiev@epam.com, Julien Grall , Stefano Stabellini , Andrii Anisov , xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org --===============2027627516704388183== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="=-VMKBMYH893RC3cEBI4xA" --=-VMKBMYH893RC3cEBI4xA Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2017-06-19 at 11:26 -0700, Volodymyr Babchuk wrote: > On 19 June 2017 at 02:37, George Dunlap > wrote: > > If you want this "EL0 app" thing to be able to provide extra > > security > > over just running the code inside of Xen, then the code must not be > > able > > to DoS the host by spinning forever instead of returning. >=20 > Right. This is a problem. Fortunately, it is running with interrupts > enabled, so next timer tick will switch back to XEN. There you can > terminate app which is running too long. >=20 What timer tick? Xen does not have one. A scheduler may setup one, if it's necessary for its own purposes, but that's entirely optional. For example, Credit does have one; Credit2, RTDS and null do not. Basically, (one of the) main purposes of this new "EL0 app mechanism" is playing behind the scheduler back. Well, fine, but then you're not allowed to assume that the scheduler will rescue you if something goes wrong. Regards, Dario --=20 <> (Raistlin Majere) ----------------------------------------------------------------- Dario Faggioli, Ph.D, http://about.me/dario.faggioli Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK) --=-VMKBMYH893RC3cEBI4xA Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAABCAAGBQJZSPJOAAoJEBZCeImluHPufYIQAN2AdT++5jjWJp3a8L99CJWg j/rYU43gmWHp83dm8Lq/qkSC+iDu0R62qQrZhuTDQI5t8zoTnailsNJ76OpXtVVq ueoGb+3b4DY9XW9iW4+P+vdRSPn6+pT7CbDrDO71atlB2tCAnXCzLkEVUYC9JjFC sF1nfwP9dqboZnoANm4Rf8db7xfeDd0ik003eQ6gc0TGygV4IFz0C0sX3iyja0ZW kXL3NCaZ/MkHj1ZQd35B4exQmwYPekNxMJ4N69wkPIqjB9sdS4BPsE97m0iCekYP AaVr72fBCZ97LZbHNx+JPIK52/m4kdsUicLODtjfV2EdIlj63wjQLDwFrcvkDKKR ZDJn4vOef35kyqDA2f0AzmsvLHwFOam0VZ6Tj9Q3KgTiIV0twhaWZhlpSDhUewyK Jy9m5WN5dTGFU4mPAnTkEjEAJZcGzK3MBwiZZKXK/Cnpxg3gg4X4soTxXTKZFZv3 FRUPi0aTCo+ByhSTfcO5J9Cs/5+g/BEc7LCGwsWkLRgsIHfdOVDUcvQ/6yNOPWGv Tz2dW8O41Ge/KB5udo9kwOXDcE2R8MGAS6XFrvphTovqAtp9D3jt9PnNaOwvXTOu zcjWAcZeJhKyqB+xtk+IqChUdqmXfMdSkj8KIOzP27Od0Ss7NCJWI/ogVGHyeOW4 js7ZAFcv8wkCXFCNpy2K =38/L -----END PGP SIGNATURE----- --=-VMKBMYH893RC3cEBI4xA-- --===============2027627516704388183== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVuLm9yZwpodHRwczovL2xpc3RzLnhlbi5v cmcveGVuLWRldmVsCg== --===============2027627516704388183==--