Messages in this thread | | | Date | Tue, 19 Apr 2022 14:06:18 +0200 | Subject | Re: [PATCH v2 06/25] x86/xen: Add ANNOTATE_ENDBR to startup_xen() | From | Juergen Gross <> |
| |
On 19.04.22 13:57, Peter Zijlstra wrote: > On Tue, Apr 19, 2022 at 11:42:12AM +0000, Andrew Cooper wrote: >> On 18/04/2022 17:50, Josh Poimboeuf wrote: >>> The startup_xen() kernel entry point is referenced by the ".note.Xen" >>> section, but is presumably not indirect-branched to. >> >> It's the real entrypoint of the VM. It's "got to" by setting %rip >> during vcpu setup. >> >> We could in principle support starting a PV VM with CET active, but that >> sounds like an enormous quantity of effort for very little gain. CET >> for Xen PV requires paravirt anyway (because the kernel runs in CPL!=0) >> so decisions like this can wait until someone feels like doing the work. >> >>> Add ANNOTATE_ENDBR >>> to silence future objtool warnings. >>> >>> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> >>> Cc: Juergen Gross <jgross@suse.com> >>> Cc: Stefano Stabellini <sstabellini@kernel.org> >>> Cc: xen-devel@lists.xenproject.org >>> Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> >> >> FWIW, Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>, preferably >> with the commit message tweaked to remove the uncertainty. > > Something like so then? > > --- > Subject: x86/xen: Add ANNOTATE_ENDBR to startup_xen() > From: Josh Poimboeuf <jpoimboe@redhat.com> > Date: Mon, 18 Apr 2022 09:50:25 -0700 > > From: Josh Poimboeuf <jpoimboe@redhat.com> > > The startup_xen() kernel entry point is referenced by the ".note.Xen" > section, and is the real entry point of the VM. It *will* be > indirectly branched to, *however* currently Xen doesn't support PV VM > with CET active.
Hmm, Xen will always use IRET to activate the guest.
Juergen [unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |