On Thu, Apr 22, 2021, Ashish Kalra wrote: > From: Brijesh Singh <brijesh.singh@xxxxxxx> > > KVM hypercall framework relies on alternative framework to patch the > VMCALL -> VMMCALL on AMD platform. If a hypercall is made before > apply_alternative() is called then it defaults to VMCALL. The approach > works fine on non SEV guest. A VMCALL would causes #UD, and hypervisor > will be able to decode the instruction and do the right things. But > when SEV is active, guest memory is encrypted with guest key and > hypervisor will not be able to decode the instruction bytes. > > Add SEV specific hypercall3, it unconditionally uses VMMCALL. The hypercall > will be used by the SEV guest to notify encrypted pages to the hypervisor. I still think we should invert the default and avoid having an SEV specific variant of kvm_hypercall3(). https://lore.kernel.org/kvm/X8gyhCsEMf8QU9H%2F@xxxxxxxxxx/
