On Thu, Nov 21, 2019 at 11:43:17AM +0100, Paolo Bonzini wrote: > 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 > Thanks Paolo! Will follow it.
