[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] x86/hvm: Allow the guest to permit the use of userspace hypercalls
On Mon, Jan 11, 2016 at 5:58 PM, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote: > On 11/01/16 17:11, Konrad Rzeszutek Wilk wrote: >> On Mon, Jan 11, 2016 at 04:51:19PM +0000, Andrew Cooper wrote: >>> Currently, hypercalls issued from HVM userspace will unconditionally fail >>> with >>> -EPERM. >>> >>> This is inflexible, and a guest may wish to allow userspace to make >>> hypercalls. >>> >>> Introduce HVMOP_set_hypercall_dpl which allows the guest to alter the >>> permissions check for hypercalls. It behaves exactly like the dpl field for >>> GDT/LDT/IDT entries. >> >> Could you explain a bit of the use-case? > > My specific usecase, > http://xenbits.xen.org/gitweb/?p=people/andrewcoop/xen-test-framework.git;a=shortlog;h=refs/heads/wip-traps-v0.1 > > It isn't quite ready for formal release yet. > >> As in why the ioctl via the kernel is no good? > > Who says Linux is running? > > Hopefully answered in > http://lists.xenproject.org/archives/html/xen-devel/2016-01/msg01155.html Not really. Obviously if you're running custom test code rather than Linux, then you aren't going to make an ioctl system call on a file descriptor; but what people are actually suggesting is just that you make *some* sort of system call from ring 3 which will then make the hypercall from ring 0. That's not "the Linux way" of doing things, it's the *operating system* way of doing things. From the previous discussion, ISTR that what you want to be able to log messages to the Xen console from your test code when running in ring 3. It should be fairly easy to set up a custom system call in your test system that will then make the appropriate hypercall from ring 0 and return, with minimal interaction with other parts of the system. (I think there were some other suggestions there as well.) Is there a reason that's not possible? -George _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |