On 07/20/2017 05:46 PM, Tamas K Lengyel wrote: > On Thu, Jul 20, 2017 at 10:43 AM, George Dunlap > <george.dun...@eu.citrix.com> wrote: >> On Wed, Jul 19, 2017 at 7:24 PM, Tamas K Lengyel <ta...@tklengyel.com> wrote: >>>> I think the issue would be whether to allow a domain to set/clear the >>>> suppress #VE bit for its pages by calling the new HVMOP on itself. >>> >>> This problem is not limited to setting the SVE bit. It also applies to >>> swapping altp2m views. Pretty much all altp2m HVMOPs can be issued >>> from a user-space program without any way to check whether that >>> process is allowed to do that or not. If you don't think it is safe >>> for a domain to set SVE, the none of the altp2m ops are safe for the >>> domain to issue on itself. If we could say ensure only the kernel can >>> issue the hvmops, that would be OK. But that's not possible at the >>> moment AFAICT. >> >> Wait, is that right? I think we normally restrict hypercalls to only >> being made from the guest kernel, don't we? >> > > If that's the case then it's good to know (can you point me where that > restriction is done?) I was just referring to the fact that > technically a userspace program can issue VMCALL.
Well for vmcall in particular, it's in xen/arch/x86/hvm/hypercall/hvm_hypercall(). The check for PV guests is in xen/arch/x86/x86_64/entry.S:lstar_enter. Other checks are left as an exercise for the reader. :-) -George _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
