lkml.org 
[lkml]   [2019]   [Jun]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH v3 0/9] Enable Sub-page Write Protection Support
From
Date
On 06/06/19 17:28, Yang Weijiang wrote:
> EPT-Based Sub-Page write Protection(SPP)is a HW capability which
> allows Virtual Machine Monitor(VMM) to specify write-permission for
> guest physical memory at a sub-page(128 byte) granularity. When this
> capability is enabled, the CPU enforces write-access check for
> sub-pages within a 4KB page.
>
> The feature is targeted to provide fine-grained memory protection
> for usages such as device virtualization, memory check-point 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), SPPT is referenced via a 64-bit control field
> called Sub-Page Permission Table Pointer (SPPTP) which contains a
> 4K-aligned physical address.
>
> Right now, only 4KB physical pages are supported for SPP. To enable SPP
> for certain physical page, we need to first make the physical page
> write-protected, then set bit 61 of the corresponding EPT leaf entry.
> While HW walks EPT, if bit 61 is set, it traverses SPPT with the guset
> physical address to find out the sub-page permissions at the leaf entry.
> If the corresponding bit is set, write to sub-page is permitted,
> otherwise, SPP induced EPT vilation is generated.
>
> 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
>
> Previous patch:
> https://lkml.org/lkml/2018/11/30/605
>
> Patch 1: Introduction to SPP.
> Patch 2: Add SPP related flags and control bits.
> Patch 3: Functions for SPPT setup.
> Patch 4: Add SPP access bitmaps for memslots.
> Patch 5: Low level implementation of SPP operations.
> Patch 6: Implement User space access IOCTLs.
> Patch 7: Handle SPP induced VMExit and EPT violation.
> Patch 8: Enable lazy mode SPPT setup.
> Patch 9: Handle memory remapping and reclaim.
>
>
> Change logs:
>
> 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
> KVM: VMX: Add control flags for SPP enabling
> KVM: VMX: Implement functions for SPPT paging setup
> KVM: VMX: Introduce SPP access bitmap and operation functions
> KVM: VMX: Add init/set/get functions for SPP
> KVM: VMX: Introduce SPP user-space IOCTLs
> KVM: VMX: Handle SPP induced vmexit and page fault
> KVM: MMU: Enable Lazy mode SPPT setup
> KVM: MMU: Handle host memory remapping and reclaim
>
> Documentation/virtual/kvm/spp_kvm.txt | 216 ++++++++++++
> arch/x86/include/asm/cpufeatures.h | 1 +
> arch/x86/include/asm/kvm_host.h | 26 +-
> 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 | 469 ++++++++++++++++++++++++++
> arch/x86/kvm/mmu.h | 1 +
> arch/x86/kvm/vmx/capabilities.h | 5 +
> arch/x86/kvm/vmx/vmx.c | 138 ++++++++
> arch/x86/kvm/x86.c | 141 ++++++++
> include/linux/kvm_host.h | 9 +
> include/uapi/linux/kvm.h | 17 +
> 13 files changed, 1038 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/virtual/kvm/spp_kvm.txt
>

Please add testcases in tools/testing/selftests/kvm.

Paolo

\
 
 \ /
  Last update: 2019-06-07 15:28    [W:0.099 / U:2.476 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site