On Mon, Mar 08, 2021, Paolo Bonzini wrote: > On 08/03/21 17:44, Sean Christopherson wrote: > > VMCALL is also probably ok > > in most scenarios, but patching L2's code from L0 KVM is sketchy. > > I agree that patching is sketchy and I'll send a patch. However... > > > > The same is true for the VMware #GP interception case. > > > > I highly doubt that will ever work out as intended for the modified IO #GP > > behavior. The only way emulating #GP in L2 is correct if L1 wants to pass > > through the capabilities to L2, i.e. the I/O access isn't intercepted by L1. > > That seems unlikely. > > ... not all hypervisors trap everything. In particular in this case the > VMCS12 I/O permission bitmap should be consulted (which we do in > vmx_check_intercept_io), but if the I/O is not trapped by L1 it should > bypass the IOPL and TSS-bitmap checks in my opinion.
I agree, _if_ it's not trapped. But bypassing the checks when it is trapped is clearly wrong.
