Re: [PATCH v5 0/7] KVM: PKS Virtualization support

[Chenyi Qiang <chenyi.qiang@intel.com>]

On 10/25/2021 11:12 PM, Paolo Bonzini wrote:
> On 11/08/21 12:11, Chenyi Qiang wrote:
>> This patch series is based on top of kernel patchset:
>> https://lore.kernel.org/lkml/20210804043231.2655537-1-ira.weiny@intel.com/ 
>>
>>
>> To help patches review, one missing info in SDM is that PKSR will be
>> cleared on Powerup/INIT/RESET, which should be listed in Table 9.1
>> "IA-32 and Intel 64 Processor States Following Power-up, Reset, or INIT"
>>
>> ---
>>
>> Protection Keys for Supervisor Pages(PKS) is a feature that extends the
>> Protection Keys architecture to support thread-specific permission
>> restrictions on supervisor pages.
>>
>> PKS works similar to an existing feature named PKU(protecting user 
>> pages).
>> They both perform an additional check after normal paging permission
>> checks are done. Access or Writes can be disabled via a MSR update
>> without TLB flushes when permissions changes. If violating this
>> addional check, #PF occurs and PFEC.PK bit will be set.
>>
>> PKS introduces MSR IA32_PKRS to manage supervisor protection key
>> rights. The MSR contains 16 pairs of ADi and WDi bits. Each pair
>> advertises on a group of pages with the same key which is set in the
>> leaf paging-structure entries(bits[62:59]). Currently, IA32_PKRS is not
>> supported by XSAVES architecture.
>>
>> This patchset aims to add the virtualization of PKS in KVM. It
>> implemented PKS CPUID enumeration, vmentry/vmexit configuration, MSR
>> exposure, nested supported etc. Currently, PKS is not yet supported for
>> shadow paging.
>>
>> Detailed information about PKS can be found in the latest Intel 64 and
>> IA-32 Architectures Software Developer's Manual.
> 
> Hi Chenyi,
> 
> pkrs_cache does not yet exist in Linux 5.15.  What is the state of the 
> bare-metal support for PKS?
> 
> Thanks,
> 
> Paolo
> 

Hi Paolo,

The latest version is still at
https://lore.kernel.org/lkml/20210804043231.2655537-1-ira.weiny@intel.com/

Ira is working on the next version but doesn't have concrete schedule.

Thanks
Chenyi

>>
>> ---
>>
>> Changelogs:
>>
>> v4->v5
>> - Make setting of MSR intercept/vmcs control bits not dependent on 
>> guest.CR4.PKS.
>>    And set them if PKS is exposed to guest. (Suggested by Sean)
>> - Add pkrs to standard register caching mechanism to help update
>>    vcpu->arch.pkrs on demand. Add related helper functions. (Suggested 
>> by Sean)
>> - Do the real pkrs update in VMCS field in vmx_vcpu_reset and
>>    vmx_sync_vmcs_host_state(). (Sean)
>> - Add a new mmu_role cr4_pks instead of smushing PKU and PKS together.
>>    (Sean & Paolo)
>> - v4: 
>> https://lore.kernel.org/lkml/20210205083706.14146-1-chenyi.qiang@intel.com/ 
>>
>>
>> v3->v4
>> - Make the MSR intercept and load-controls setting depend on CR4.PKS 
>> value
>> - shadow the guest pkrs and make it usable in PKS emultion
>> - add the cr4_pke and cr4_pks check in pkr_mask update
>> - squash PATCH 2 and PATCH 5 to make the dependencies read more clear
>> - v3: 
>> https://lore.kernel.org/lkml/20201105081805.5674-1-chenyi.qiang@intel.com/ 
>>
>>
>> v2->v3:
>> - No function changes since last submit
>> - rebase on the latest PKS kernel support:
>>    
>> https://lore.kernel.org/lkml/20201102205320.1458656-1-ira.weiny@intel.com/ 
>>
>> - add MSR_IA32_PKRS to the vmx_possible_passthrough_msrs[]
>> - RFC v2: 
>> https://lore.kernel.org/lkml/20201014021157.18022-1-chenyi.qiang@intel.com/ 
>>
>>
>> v1->v2:
>> - rebase on the latest PKS kernel support:
>>    https://github.com/weiny2/linux-kernel/tree/pks-rfc-v3
>> - add a kvm-unit-tests for PKS
>> - add the check in kvm_init_msr_list for PKRS
>> - place the X86_CR4_PKS in mmu_role_bits in kvm_set_cr4
>> - add the support to expose VM_{ENTRY, EXIT}_LOAD_IA32_PKRS in nested
>>    VMX MSR
>> - RFC v1: 
>> https://lore.kernel.org/lkml/20200807084841.7112-1-chenyi.qiang@intel.com/ 
>>
>>
>> ---
>>
>> Chenyi Qiang (7):
>>    KVM: VMX: Introduce PKS VMCS fields
>>    KVM: VMX: Add proper cache tracking for PKRS
>>    KVM: X86: Expose IA32_PKRS MSR
>>    KVM: MMU: Rename the pkru to pkr
>>    KVM: MMU: Add support for PKS emulation
>>    KVM: VMX: Expose PKS to guest
>>    KVM: VMX: Enable PKS for nested VM
>>
>>   arch/x86/include/asm/kvm_host.h | 17 ++++---
>>   arch/x86/include/asm/vmx.h      |  6 +++
>>   arch/x86/kvm/cpuid.c            |  2 +-
>>   arch/x86/kvm/kvm_cache_regs.h   |  7 +++
>>   arch/x86/kvm/mmu.h              | 25 +++++----
>>   arch/x86/kvm/mmu/mmu.c          | 68 ++++++++++++++-----------
>>   arch/x86/kvm/vmx/capabilities.h |  6 +++
>>   arch/x86/kvm/vmx/nested.c       | 41 ++++++++++++++-
>>   arch/x86/kvm/vmx/vmcs.h         |  1 +
>>   arch/x86/kvm/vmx/vmcs12.c       |  2 +
>>   arch/x86/kvm/vmx/vmcs12.h       |  4 ++
>>   arch/x86/kvm/vmx/vmx.c          | 89 ++++++++++++++++++++++++++++++---
>>   arch/x86/kvm/vmx/vmx.h          |  7 ++-
>>   arch/x86/kvm/x86.c              |  6 ++-
>>   arch/x86/kvm/x86.h              |  8 +++
>>   arch/x86/mm/pkeys.c             |  6 +++
>>   include/linux/pkeys.h           |  5 ++
>>   17 files changed, 243 insertions(+), 57 deletions(-)
>>
>