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

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Date:   Thu, 26 Aug 2021 10:04:40 +0800
From:   Chenyi Qiang <chenyi.qiang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/7] KVM: PKS Virtualization support

Ping for comments.

One thing to pay attention:
The previous statement was incorrect – PKRS should be preserved on INIT, 
not cleared.


On 8/11/2021 6:11 PM, 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.
> 
> 
> ---
> 
> 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(-)
>