Messages in this thread | | | Date | Wed, 28 Jul 2021 23:22:47 +0200 | From | Frederic Weisbecker <> | Subject | Re: [patch 1/4] add basic task isolation prctl interface |
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On Wed, Jul 28, 2021 at 10:21:34AM -0300, Marcelo Tosatti wrote: > > > ISOL_FEATURES is just the "command" type (which you can get and set). > > > > > > The bitmask would include ISOL_F_QUIESCE_ON_URET, so: > > > > > > - bitmask = ISOL_F_QUIESCE_ON_URET; > > > - prctl(PR_ISOL_SET, ISOL_FEATURES, bitmask, 0, 0) enables the features in > > > the bitmask. > > > > But does it quiesce once or for every further uret? > > For every uret, while ISOL_F_QUIESCE_ON_URET is enabled through > prctl(PR_ISOL_ENABLE, enabled_bitmask, 0, 0, 0).
Ok.
> > > > - quiesce_bitmap = prctl(PR_ISOL_GET, PR_ISOL_SUP_QUIESCE_CFG, 0, 0, 0) > > > (1) > > > > > > (returns the supported actions to be quiesced). > > > > > > - prctl(PR_ISOL_SET, PR_ISOL_QUIESCE_CFG, quiesce_bitmask, 0, 0) _sets_ > > > the actions to be quiesced (2) > > > > > > If an application does not modify "quiesce_bitmask" between > > > points (1) and (2) above, it will enable quiescing of all > > > "features" the kernel supports. > > > > I don't get the difference between ISOL_FEATURES and PR_ISOL_QUIESCE_CFG. > > prctl(PR_ISOL_SET, cmd, ...) is intented to accept different types of "command" > variables (including ones for new features which are not known at this > time). > > - prctl(PR_ISOL_SET, ISOL_FEATURES, bitmask, 0, 0) enables the features in > the bitmask > > (which might now be superceded by > > prctl(PR_ISOL_ENABLE, ISOL_F_QUIESCE_ON_URET, 0, 0, 0)) > > - prctl(PR_ISOL_SET, PR_ISOL_QUIESCE_CFG, bitmask, 0, 0) configures > quiescing of which subsystem/feature is performed: > > #define ISOL_F_QUIESCE_VMSTAT_SYNC (1<<0) > #define ISOL_F_QUIESCE_NOHZ_FULL (1<<1) > #define ISOL_F_QUIESCE_DEFER_TLB_FLUSH (1<<2)
Ok but...I still don't get the difference between ISOL_FEATURES and PR_ISOL_QUIESCE_CFG :-)
> > So PR_ISOL_ENABLE is a way to perform action when some sort of kernel entry > > happens. Then we take actions when that happens (signal, warn, etc...). > > > > I guess we'll need to define what kind of kernel entry, and what kind of > > response need to happen. Ok that's a whole issue of its own that we'll need > > to handle seperately. > > > > Thanks. > > In fact, why one can't use SECCOMP for syscall blocking?
Heh! Good point!
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