Re: [PATCH v3 0/7] KVM, pkeys: add memory protection-key support

[Paolo Bonzini <pbonzini@redhat.com>]

On 18/11/2015 06:43, Huaitong Han wrote:
> Changes in v3:
> *Add comments for patch that disable PKU feature without ept.
> 
> Changes in v2:
> *Add pku.c for kvm-unit-tests.
> *Optimize permission_fault codes for patch4.
> *Delete is_long_mode and PK for patch5.
> *Squash cpuid and cr4 patches.
> 
> The protection-key feature provides an additional mechanism by which IA-32e
> paging controls access to usermode addresses.
> 
> Hardware support for protection keys for user pages is enumerated with CPUID
> feature flag CPUID.7.0.ECX[3]:PKU. Software support is CPUID.7.0.ECX[4]:OSPKE
> with the setting of CR4.PKE(bit 22).
> 
> When CR4.PKE = 1, every linear address is associated with the 4-bit protection
> key located in bits 62:59 of the paging-structure entry that mapped the page
> containing the linear address. The PKRU register determines, for each
> protection key, whether user-mode addresses with that protection key may be
> read or written.
> 
> The PKRU register (protection key rights for user pages) is a 32-bit register
> with the following format: for each i (0 ≤ i ≤ 15), PKRU[2i] is the
> access-disable bit for protection key i (ADi); PKRU[2i+1] is the write-disable
> bit for protection key i (WDi).
> 
> Software can use the RDPKRU and WRPKRU instructions with ECX = 0 to read and
> write PKRU. In addition, the PKRU register is XSAVE-managed state and can thus
> be read and written by instructions in the XSAVE feature set.
> 
> PFEC.PK (bit 5) is defined as protection key violations.
> 
> The specification of Protection Keys can be found at SDM (4.6.2, volume 3)
> http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-manual-325462.pdf.
> 
> The kernel native patchset have not yet been merged to upstream, you can found
> at git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-pkeys.git pkeys-v007.
> 
> Huaitong Han (7):
>   KVM, pkeys: expose CPUID/CR4 to guest
>   KVM, pkeys: disable pkeys for guests in non-paging mode
>   KVM, pkeys: update memeory permission bitmask for pkeys
>   KVM, pkeys: add pkeys support for permission_fault logic
>   KVM, pkeys: Add pkeys support for gva_to_gpa funcions
>   KVM, pkeys: add pkeys support for xsave state
>   KVM, pkeys: disable PKU feature without ept
> 
>  arch/x86/include/asm/kvm_host.h | 11 +++++---
>  arch/x86/kvm/cpuid.c            | 24 ++++++++++++++++--
>  arch/x86/kvm/cpuid.h            |  8 ++++++
>  arch/x86/kvm/mmu.c              | 32 +++++++++++++++++++++--
>  arch/x86/kvm/mmu.h              | 56 +++++++++++++++++++++++++++++++++++++----
>  arch/x86/kvm/paging_tmpl.h      | 18 ++++++++++---
>  arch/x86/kvm/vmx.c              | 10 ++++----
>  arch/x86/kvm/x86.c              | 27 ++++++++++++++------
>  arch/x86/kvm/x86.h              |  3 ++-
>  9 files changed, 161 insertions(+), 28 deletions(-)
> 

Looks good, but it will have to wait for kernel PKU support.

Thanks,

Paolo