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  1. Oct 02, 2020
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    • Alexander Graf's avatar
      KVM: x86: Introduce MSR filtering · 1a155254
      Alexander Graf authored 
      

It's not desireable to have all MSRs always handled by KVM kernel space. Some
MSRs would be useful to handle in user space to either emulate behavior (like
uCode updates) or differentiate whether they are valid based on the CPU model.

To allow user space to specify which MSRs it wants to see handled by KVM,
this patch introduces a new ioctl to push filter rules with bitmaps into
KVM. Based on these bitmaps, KVM can then decide whether to reject MSR access.
With the addition of KVM_CAP_X86_USER_SPACE_MSR it can also deflect the
denied MSR events to user space to operate on.

If no filter is populated, MSR handling stays identical to before.

Signed-off-by: default avatarAlexander Graf <graf@amazon.com>

Message-Id: <20200925143422.21718-8-graf@amazon.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1a155254
    • Alexander Graf's avatar
      KVM: x86: Allow deflecting unknown MSR accesses to user space · 1ae09954
      Alexander Graf authored 
      

MSRs are weird. Some of them are normal control registers, such as EFER.
Some however are registers that really are model specific, not very
interesting to virtualization workloads, and not performance critical.
Others again are really just windows into package configuration.

Out of these MSRs, only the first category is necessary to implement in
kernel space. Rarely accessed MSRs, MSRs that should be fine tunes against
certain CPU models and MSRs that contain information on the package level
are much better suited for user space to process. However, over time we have
accumulated a lot of MSRs that are not the first category, but still handled
by in-kernel KVM code.

This patch adds a generic interface to handle WRMSR and RDMSR from user
space. With this, any future MSR that is part of the latter categories can
be handled in user space.

Furthermore, it allows us to replace the existing "ignore_msrs" logic with
something that applies per-VM rather than on the full system. That way you
can run productive VMs in parallel to experimental ones where you don't care
about proper MSR handling.

Signed-off-by: default avatarAlexander Graf <graf@amazon.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>

Message-Id: <20200925143422.21718-3-graf@amazon.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      1ae09954
    • Vitaly Kuznetsov's avatar
      KVM: x86: hyper-v: Mention SynDBG CPUID leaves in api.rst · b44f50d8
      Vitaly Kuznetsov authored 
      

We forgot to update KVM_GET_SUPPORTED_HV_CPUID's documentation in api.rst
when SynDBG leaves were added.

While on it, fix 'KVM_GET_SUPPORTED_CPUID' copy-paste error.

Fixes: f97f5a56 ("x86/kvm/hyper-v: Add support for synthetic debugger interface")
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200924145757.1035782-2-vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      b44f50d8
  7. Sep 14, 2020
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    • Randy Dunlap's avatar
      Documentation/powerpc: fix malformed table in syscall64-abi · aa661d7f
      Randy Dunlap authored 
      

Fix malformed table warning in powerpc/syscall64-abi.rst by making
two tables and moving the headings.

Documentation/powerpc/syscall64-abi.rst:53: WARNING: Malformed table.
Text in column margin in table line 2.

  =========== ============= ========================================
  --- For the sc instruction, differences with the ELF ABI ---
  r0          Volatile      (System call number.)
  r3          Volatile      (Parameter 1, and return value.)
  r4-r8       Volatile      (Parameters 2-6.)
  cr0         Volatile      (cr0.SO is the return error condition.)
  cr1, cr5-7  Nonvolatile
  lr          Nonvolatile

  --- For the scv 0 instruction, differences with the ELF ABI ---
  r0          Volatile      (System call number.)
  r3          Volatile      (Parameter 1, and return value.)
  r4-r8       Volatile      (Parameters 2-6.)
  =========== ============= ========================================

Fixes: 7fa95f9a ("powerpc/64s: system call support for scv/rfscv instructions")
Signed-off-by: default avatarRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/e06de4d3-a36f-2745-9775-467e125436cc@infradead.org
      aa661d7f
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