[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [Xen-devel] EFER in HVM guests
Jan Beulich wrote: >>>> Keir Fraser <keir@xxxxxxxxxxxxx> 29.11.06 14:09 >>> >> On 29/11/06 13:07, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote: >> >>> Is it intentional that >>> - under SVM, 32-bit guests can freely set EFER.LME >>> - under VMX, 32-bit guests can't access EFER at all? >>> >>> Thanks, Jan >> >> I'm sure any differences are unintentional. There is obviously scope >> for making much of the MSR and CPUID code non-vmx/svm specific. >> >> I assume that this particular difference doesn't really matter? > > I think it does - allowing a guest to enable EFER.LME when the > hypervisor is a 32-bit one is clearly a security problem: While I > haven't tried it, I would suspect the moment you load a context > with such an EFER the whole system's dead. > Not being able to access EFER is also a potential problem, as a > guest should be allowed to set EFER.NX (at least) - the CPUID > handling code specifically does not suppress this bit if the guest > is allowed to use PAE (which we agreed a few days ago should > be the default anyway). > > Jan > I agree that we should allow 32-bit guests to set EFER.NX on the PAE Xen. We'll fix it. EFER.SCE should not be set on IA-32. Jun --- Intel Open Source Technology Center _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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