From: bp@alien8.de (Borislav Petkov) Date: Mon, 8 Feb 2016 16:55:07 +0100 Subject: [Cocci] [PATCH v2 3/3] paravirt: rename paravirt_enabled to paravirt_legacy In-Reply-To: <56B8B6BF.6030007@oracle.com> References: <1454733014-15237-1-git-send-email-mcgrof@kernel.org> <1454733014-15237-4-git-send-email-mcgrof@kernel.org> <20160206085930.GF25240@wotan.suse.de> <20160206220437.GA4435@pd.tnic> <56B8B6BF.6030007@oracle.com> Message-ID: <20160208155507.GF28980@pd.tnic> To: cocci@systeme.lip6.fr List-Id: cocci@systeme.lip6.fr On Mon, Feb 08, 2016 at 10:39:43AM -0500, Boris Ostrovsky wrote: > It does. Very much IIRC, the problem was not caused by an access to MSR but > rather some sort of address not being available somewhere. See below. > >- microcode application on Xen: we've had this before. The hypervisor > >should do that (if it doesn't do so already). > > it does. Good. > >So yes, that paravirt_enabled() thing should go away. Even more so if we > >have CPUID leaf 0x4... reserved for hypervisors. > > I actually think this was the original proposal until we realized we had > paravirt_enabled(). So we can go back to checking CPUID 0x40000000. > > We might also be able to test for (x86_hyper!=NULL) and have guests that do > microcode management prior to init_hypervisor() rely on hypervisors ignoring > MSR accesses (as they do today). Right, so the early loader can't do that as on 32-bit it runs even before paging has been enabled. So I *think* the thing with CPUID would be best. What does the xen hypervisor return in regs when I do CPUID(4)? I.e., how do I reliably detect it in the guest? I can whip up a quick patch and get rid of paravirt_enabled() while at it... -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply.