On 2022/10/12 19:01, Huang, Kai wrote: > On Wed, 2022-10-12 at 13:09 +0800, Zhiquan Li wrote: >>>> SGX virtual EPC driver doesn't explicitly prevent virtual EPC instance >>>> being shared by multiple VMs via fork(). However KVM doesn't support >>>> running a VM across multiple mm structures, and the de facto userspace >>>> hypervisor (Qemu) doesn't use fork() to create a new VM, so in practice >>>> this should not happen. >>> >>> This is out of the blue. Why is this here? >>> >>> What happens if a hypervisor *DOES* fork()? What's the fallout? >> >> This part originates from below discussion: >> >> https://lore.kernel.org/linux-sgx/52dc7f50b68c99cecb9e1c3383d9c6d88734cd67.camel@xxxxxxxxx/#t >> >> It intents to answer the question: >> >> Do you think the processes sharing the same enclave need to be >> killed, even they had not touched the EPC page with hardware error? > > Sharing virtual EPC instance will very likely unexpectedly break enclaves in all > VMs. Whether kernel should explicitly prevent is another topic. To me I don't > see strong reason to enforce in the kernel. For instance, multiple VMs can map > the same file as memory backend with MAP_SHARED, in which case they can all > break. Userspace should use virtual EPC in the right way. > > But the point is above is not directly related to your patch. On host where > multiple processes can share one enclave legally, it does the same thing. I > think you can just remove that paragraph from changelog. > OK, I'll remove it since V10. Thank you all the same, Kai.
