On 19/11/19 09:49, Yang Weijiang wrote: > EPT-Based Sub-Page write Protection(SPP) allows Virtual Machine Monitor(VMM) > specify write-permission for guest physical memory at a sub-page(128 byte) > granularity. When SPP works, HW enforces write-access check for sub-pages > within a protected 4KB page. > > The feature targets to provide fine-grained memory protection for > usages such as memory guard and VM introspection etc. > > SPP is active when the "sub-page write protection" (bit 23) is 1 in > Secondary VM-Execution Controls. The feature is backed with a Sub-Page > Permission Table(SPPT), and subpage permission vector is stored in the > leaf entry of SPPT. The root page is referenced via a Sub-Page Permission > Table Pointer (SPPTP) in VMCS. > > To enable SPP for guest memory, the guest page should be first mapped > to a 4KB EPT entry, then set SPP bit 61 of the corresponding entry. > While HW walks EPT, it traverses SPPT with the gpa to look up the sub-page > permission vector within SPPT leaf entry. If the corresponding bit is set, > write to sub-page is permitted, otherwise, SPP induced EPT violation is generated. > > This patch serial passed SPP function test and selftest on Ice-Lake platform. > > Please refer to the SPP introduction document in this patch set and > Intel SDM for details: > > Intel SDM: > https://software.intel.com/sites/default/files/managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf > > SPP selftest patch: > https://lkml.org/lkml/2019/6/18/1197 On top of the changes I sent for the individual patches, please move vmx/spp.c to mmu/spp.c, and vmx/spp.h to spp.h (I've just sent a patch to create the mmu/ directory). Also, please include the selftest in this series. Paolo > Patch 1: Documentation for SPP and related API. > Patch 2: Add control flags for Sub-Page Protection(SPP). > Patch 3: Add SPP Table setup functions. > Patch 4: Add functions to create/destroy SPP bitmap block. > Patch 5: Introduce user-space SPP IOCTLs. > Patch 6: Set up SPP paging table at vmentry/vmexit. > Patch 7: Enable Lazy mode SPP protection. > Patch 8: Handle SPP protected pages when VM memory changes. > Patch 9: Add SPP protection check in emulation case. > > > Change logs: > V6 -> V7: > 1. Configured all available protected pages once SPP induced vmexit > happens since there's no PRESENT bit in SPPT leaf entry. > 2. Changed SPP protection check flow in tdp_page_fault(). > 3. Code refactor and minior fixes. > > V5 -> V6: > 1. Added SPP protection patch for emulation cases per Jim's review. > 2. Modified documentation and added API description per Jim's review. > 3. Other minior changes suggested by Jim. > > V4 -> V5: > 1. Enable SPP support for Hugepage(1GB/2MB) to extend application. > 2. Make SPP miss vm-exit handler as the unified place to set up SPPT. > 3. If SPP protected pages are access-tracked or dirty-page-tracked, > store SPP flag in reserved address bit, restore it in > fast_page_fault() handler. > 4. Move SPP specific functions to vmx/spp.c and vmx/spp.h > 5. Rebased code to kernel v5.3 > 6. Other change suggested by KVM community. > > V3 -> V4: > 1. Modified documentation to make it consistent with patches. > 2. Allocated SPPT root page in init_spp() instead of vmx_set_cr3() to > avoid SPPT miss error. > 3. Added back co-developers and sign-offs. > > V2 -> V3: > 1. Rebased patches to kernel 5.1 release > 2. Deferred SPPT setup to EPT fault handler if the page is not > available while set_subpage() is being called. > 3. Added init IOCTL to reduce extra cost if SPP is not used. > 4. Refactored patch structure, cleaned up cross referenced functions. > 5. Added code to deal with memory swapping/migration/shrinker cases. > > V2 -> V1: > 1. Rebased to 4.20-rc1 > 2. Move VMCS change to a separated patch. > 3. Code refine and Bug fix > > > Yang Weijiang (9): > Documentation: Introduce EPT based Subpage Protection and related > ioctls > vmx: spp: Add control flags for Sub-Page Protection(SPP) > mmu: spp: Add SPP Table setup functions > mmu: spp: Add functions to create/destroy SPP bitmap block > x86: spp: Introduce user-space SPP IOCTLs > vmx: spp: Set up SPP paging table at vmentry/vmexit > mmu: spp: Enable Lazy mode SPP protection > mmu: spp: Handle SPP protected pages when VM memory changes > x86: spp: Add SPP protection check in emulation. > > Documentation/virt/kvm/api.txt | 46 ++ > Documentation/virtual/kvm/spp_kvm.txt | 180 +++++++ > arch/x86/include/asm/cpufeatures.h | 1 + > arch/x86/include/asm/kvm_host.h | 10 +- > arch/x86/include/asm/vmx.h | 10 + > arch/x86/include/uapi/asm/vmx.h | 2 + > arch/x86/kernel/cpu/intel.c | 4 + > arch/x86/kvm/mmu.c | 78 ++- > arch/x86/kvm/mmu.h | 2 + > arch/x86/kvm/vmx/capabilities.h | 5 + > arch/x86/kvm/vmx/spp.c | 651 ++++++++++++++++++++++++++ > arch/x86/kvm/vmx/spp.h | 28 ++ > arch/x86/kvm/vmx/vmx.c | 113 +++++ > arch/x86/kvm/x86.c | 87 ++++ > include/uapi/linux/kvm.h | 17 + > 15 files changed, 1232 insertions(+), 2 deletions(-) > create mode 100644 Documentation/virtual/kvm/spp_kvm.txt > create mode 100644 arch/x86/kvm/vmx/spp.c > create mode 100644 arch/x86/kvm/vmx/spp.h >
