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@linux.in...
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:
- PMPAT - PrivateMemoryPrivateAccess test passes
- 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;
Regards Nikunj
[1] https://lore.kernel.org/all/20220310140911.50924-10-chao.p.peng@linux.intel....