On Mon, Apr 11, 2022 at 05:31:09PM +0530, Nikunj A. Dadhania wrote: > On 4/9/2022 2:35 AM, Vishal Annapurve wrote: > > This series implements selftests targeting the feature floated by Chao > > via: > > https://lore.kernel.org/linux-mm/20220310140911.50924-1-chao.p.peng@xxxxxxxxxxxxxxx/ > > > > Thanks for working on this. > > > Below changes aim to test the fd based approach for guest private memory > > in context of normal (non-confidential) VMs executing on non-confidential > > platforms. > > > > Confidential platforms along with the confidentiality aware software > > stack support a notion of private/shared accesses from the confidential > > VMs. > > Generally, a bit in the GPA conveys the shared/private-ness of the > > access. Non-confidential platforms don't have a notion of private or > > shared accesses from the guest VMs. To support this notion, > > KVM_HC_MAP_GPA_RANGE > > is modified to allow marking an access from a VM within a GPA range as > > always shared or private. Any suggestions regarding implementing this ioctl > > alternatively/cleanly are appreciated. > > > > priv_memfd_test.c file adds a suite of two basic selftests to access private > > memory from the guest via private/shared access and checking if the contents > > can be leaked to/accessed by vmm via shared memory view. > > > > Test results: > > 1) PMPAT - PrivateMemoryPrivateAccess test passes > > 2) PMSAT - PrivateMemorySharedAccess test fails currently and needs more > > analysis to understand the reason of failure. > > That could be because of the return code (*r = -1) from the KVM_EXIT_MEMORY_ERROR. > This gets interpreted as -EPERM in the VMM when the vcpu_run exits. > > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_ERROR; > + vcpu->run->memory.flags = flags; > + vcpu->run->memory.padding = 0; > + vcpu->run->memory.gpa = fault->gfn << PAGE_SHIFT; > + vcpu->run->memory.size = PAGE_SIZE; > + fault->pfn = -1; > + *r = -1; > + return true; That's true. The current private mem patch treats KVM_EXIT_MEMORY_ERROR as error for KVM_RUN. That behavior needs to be discussed, but right now (v5) it hits the ASSERT in tools/testing/selftests/kvm/lib/kvm_util.c before you have chance to handle KVM_EXIT_MEMORY_ERROR in this patch series. void vcpu_run(struct kvm_vm *vm, uint32_t vcpuid) { int ret = _vcpu_run(vm, vcpuid); TEST_ASSERT(ret == 0, "KVM_RUN IOCTL failed, " "rc: %i errno: %i", ret, errno); } Thanks, Chao > > > Regards > Nikunj > > [1] https://lore.kernel.org/all/20220310140911.50924-10-chao.p.peng@xxxxxxxxxxxxxxx/#t
