Hi Dave, Any more comments for v6? Thanks! > -----Original Message----- > From: Li, Zhiquan1 <zhiquan1.li@xxxxxxxxx> > Sent: Saturday, July 23, 2022 8:24 PM > To: linux-sgx@xxxxxxxxxxxxxxx; Luck, Tony <tony.luck@xxxxxxxxx>; > jarkko@xxxxxxxxxx; dave.hansen@xxxxxxxxxxxxxxx > Cc: Christopherson,, Sean <seanjc@xxxxxxxxxx>; Huang, Kai > <kai.huang@xxxxxxxxx>; Du, Fan <fan.du@xxxxxxxxx>; Zhang, Cathy > <cathy.zhang@xxxxxxxxx>; Li, Zhiquan1 <zhiquan1.li@xxxxxxxxx> > Subject: [PATCH v6 0/3] x86/sgx: fine grained SGX MCA behavior > > V5: https://lore.kernel.org/linux-sgx/Yrf27fugD7lkyaek@xxxxxxxxxx/T/#t > > Changes since V5: > - Rename the 'owner' field as 'encl_owner' and update the references > as a separate patch. > - To prevent casting the 'encl_owner' field, introduce a union with > another field - "vepc_vaddr". > - Clean up the commit message of patch 02 suggested by Dave. > - Remove patch 03 unless there is a better reason to keep it. > - Add Reviewed-by from Jarkko. > > V4: https://lore.kernel.org/linux-sgx/20220608032654.1764936-1- > zhiquan1.li@xxxxxxxxx/T/#t > > Changes since V4: > - Switch the order of the two variables at patch 02 so all of variables > are in reverse Christmas style. > - Do not initialize 'ret' because it will be overridden by the return > value of force_sig_mceerr() unconditionally. > - Add Co-developed-by and Signed-off-by from Cathy Zhang at patch 01. > - Add Acked-by from Kai Huang at patch 01. > > V3: https://lore.kernel.org/linux- > sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@xxxxxxxxxx/T/#t > > Changes since V3: > - Take the definition of EPC page flag SGX_EPC_PAGE_KVM_GUEST from > Cathy Zhang's third patch of SGX rebootless recovery patch set but > discard irrelevant portion, since it might need some time to re-forge > and these are two different features. > Link: https://lore.kernel.org/linux- > sgx/41704e5d4c03b49fcda12e695595211d950cfb08.camel@xxxxxxxxxx/T/#m > 9782d23496cacecb7da07a67daa79f4b322ae170 > > V2: https://lore.kernel.org/linux-sgx/694234d7-6a0d-e85f-f2f9- > e52b4a61e1ec@xxxxxxxxx/T/#t > > Changes since V2: > - Repurpose the owner field as the virtual address of virtual EPC page > - Remove struct sgx_vepc_page and relevant code. > - Remove patch 01 as the changes are not necessary in new design. > - Rework patch 02 suggested by Jarkko. > - Adapt patch 03 and 04 since struct sgx_vepc_page was discarded. > - Replace EPC page flag SGX_EPC_PAGE_IS_VEPC with > SGX_EPC_PAGE_KVM_GUEST as they are duplicated. > Link: https://lore.kernel.org/linux- > sgx/eb95b32ecf3d44a695610cf7f2816785@xxxxxxxxx/T/#u > > V1: https://lore.kernel.org/linux-sgx/443cb425-009c-2784-56f4- > 5e707122de76@xxxxxxxxx/T/#t > > Changes since V1: > - Updated cover letter and commit messages, added valuable > information from Jarkko, Tony and Kai's comments. > - Added documentations for struct struct sgx_vepc and > struct sgx_vepc_page. > > Hi everyone, > > This series contains a few patches to fine grained SGX MCA behavior. > > Today, if a guest accesses an SGX EPC page with memory failure, > the kernel behavior will kill the entire guest. This blast > radius is too large. It would be idea to kill only the SGX > application inside the guest. > > To fix this, send a SIGBUS to host userspace (like QEMU) which can > follow up by injecting a #MC to the guest. > > However, when a page triggers a machine check, it only reports the > PFN. But in order to inject #MC into hypervisor, the virtual address > is required. The 'encl_owner' field is useless in virtualization > case, then repurpose it as 'vepc_vaddr' - the virtual address of the > virtual EPC page in such case so that arch_memory_failure() can easily > retrieve it. > > Suppose an enclave is shared by multiple processes, when an enclave > page triggers a machine check, the enclave will be disabled so that > it couldn't be entered again. Killing other processes with the same > enclave mapped would perhaps be overkill, but they are going to find > that the enclave is "dead" next time they try to use it. Thanks for > Jarkko’s head up and Tony’s clarification on this point. > > Unlike host enclaves, virtual EPC instance cannot be shared by multiple > VMs. It is because how enclaves are created is totally up to the guest. > Sharing virtual EPC instance will be very likely to unexpectedly break > enclaves in all VMs. > > 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 series is based on tip/x86/sgx. > > Tests: > 1. MCE injection test for SGX in VM. > As we expected, the application was killed and VM was alive. > 2. Kernel selftest/sgx: PASS > 3. Internal SGX stress test: PASS > 4. kmemleak test: No memory leakage detected. > > Much appreciate your feedback. > > Best Regards, > Zhiquan > > Zhiquan Li (3): > x86/sgx: Rename the owner field of struct sgx_epc_page as encl_owner > x86/sgx: Introduce union with vepc_vaddr field for virtualization case > x86/sgx: Fine grained SGX MCA behavior for virtualization > > arch/x86/kernel/cpu/sgx/main.c | 48 +++++++++++++++++++++++++--------- > arch/x86/kernel/cpu/sgx/sgx.h | 8 +++++- > arch/x86/kernel/cpu/sgx/virt.c | 4 ++- > 3 files changed, 46 insertions(+), 14 deletions(-) > > -- > 2.25.1
