[PATCH v2 00/32] KVM: x86: Clean up MSR interception code

[Sean Christopherson <seanjc@google.com>]

Clean up KVM's MSR interception code (especially the SVM code, which is all
kinds of ugly).  The main goals are to:

 - Make the SVM and VMX APIs consistent (and sane; the current SVM APIs have
   inverted polarity).

 - Eliminate the shadow bitmaps that are used to determine intercepts on
   userspace MSR filter update.

v2:
 - Add a patch to set MSR_IA32_SPEC_CTRL interception as appropriate. [Chao]
 - Add a patch to cleanup {svm,vmx}_disable_intercept_for_msr() once the
   dust has settled. [Dapeng]
 - Return -ENOSPC if msrpm_offsets[] is full. [Chao]
 - Free iopm_pages directly instead of bouncing through iopm_base. [Chao]
 - Check for "offset == MSR_INVALID" before using offset. [Chao]
 - Temporarily keep MSR_IA32_DEBUGCTLMSR in the nested list. [Chao]
 - Add a comment to explain nested_svm_msrpm_merge_offsets. [Chao]
 - Add a patch to shift the IOPM allocation to avoid having to unwind it.
 - Init nested_svm_msrpm_merge_offsets iff nested=1. [Chao]
 - Add a helper to dedup alloc+init of MSRPM and IOPM.
 - Tag merge_msrs as "static" and "__initconst". [Paolo]
 - Rework helpers to use fewer macros. [Paolo]
 - Account for each MSRPM byte covering 4 MSRs. [Paolo]
 - Opportunistically use cpu_feature_enabled(). [Xin]
 - Fully remove MAX_DIRECT_ACCESS_MSRS, MSRPM_OFFSETS, and msrpm_offsets.
   [Francesco]
 - Fix typos. [Dapeng, Chao]
 - Collect reviews. [Chao, Dapeng, Xin]

v1: https://lore.kernel.org/all/20250529234013.3826933-1-seanjc@google.com

v0: https://lore.kernel.org/kvm/20241127201929.4005605-1-aaronlewis@google.com

Sean Christopherson (32):
  KVM: SVM: Disable interception of SPEC_CTRL iff the MSR exists for the
    guest
  KVM: SVM: Allocate IOPM pages after initial setup in
    svm_hardware_setup()
  KVM: SVM: Don't BUG if setting up the MSR intercept bitmaps fails
  KVM: SVM: Tag MSR bitmap initialization helpers with __init
  KVM: SVM: Use ARRAY_SIZE() to iterate over direct_access_msrs
  KVM: SVM: Kill the VM instead of the host if MSR interception is buggy
  KVM: x86: Use non-atomic bit ops to manipulate "shadow" MSR intercepts
  KVM: SVM: Massage name and param of helper that merges vmcb01 and
    vmcb12 MSRPMs
  KVM: SVM: Clean up macros related to architectural MSRPM definitions
  KVM: nSVM: Use dedicated array of MSRPM offsets to merge L0 and L1
    bitmaps
  KVM: nSVM: Omit SEV-ES specific passthrough MSRs from L0+L1 bitmap
    merge
  KVM: nSVM: Don't initialize vmcb02 MSRPM with vmcb01's "always
    passthrough"
  KVM: SVM: Add helpers for accessing MSR bitmap that don't rely on
    offsets
  KVM: SVM: Implement and adopt VMX style MSR intercepts APIs
  KVM: SVM: Pass through GHCB MSR if and only if VM is an SEV-ES guest
  KVM: SVM: Drop "always" flag from list of possible passthrough MSRs
  KVM: x86: Move definition of X2APIC_MSR() to lapic.h
  KVM: VMX: Manually recalc all MSR intercepts on userspace MSR filter
    change
  KVM: SVM: Manually recalc all MSR intercepts on userspace MSR filter
    change
  KVM: x86: Rename msr_filter_changed() => recalc_msr_intercepts()
  KVM: SVM: Rename init_vmcb_after_set_cpuid() to make it intercepts
    specific
  KVM: SVM: Fold svm_vcpu_init_msrpm() into its sole caller
  KVM: SVM: Merge "after set CPUID" intercept recalc helpers
  KVM: SVM: Drop explicit check on MSRPM offset when emulating SEV-ES
    accesses
  KVM: SVM: Move svm_msrpm_offset() to nested.c
  KVM: SVM: Store MSRPM pointer as "void *" instead of "u32 *"
  KVM: nSVM: Access MSRPM in 4-byte chunks only for merging L0 and L1
    bitmaps
  KVM: SVM: Return -EINVAL instead of MSR_INVALID to signal out-of-range
    MSR
  KVM: nSVM: Merge MSRPM in 64-bit chunks on 64-bit kernels
  KVM: SVM: Add a helper to allocate and initialize permissions bitmaps
  KVM: x86: Simplify userspace filter logic when disabling MSR
    interception
  KVM: selftests: Verify KVM disable interception (for userspace) on
    filter change

 arch/x86/include/asm/kvm-x86-ops.h            |   2 +-
 arch/x86/include/asm/kvm_host.h               |   2 +-
 arch/x86/kvm/lapic.h                          |   2 +
 arch/x86/kvm/svm/nested.c                     | 126 +++--
 arch/x86/kvm/svm/sev.c                        |  29 +-
 arch/x86/kvm/svm/svm.c                        | 490 ++++++------------
 arch/x86/kvm/svm/svm.h                        | 102 +++-
 arch/x86/kvm/vmx/main.c                       |   6 +-
 arch/x86/kvm/vmx/vmx.c                        | 202 ++------
 arch/x86/kvm/vmx/vmx.h                        |   9 -
 arch/x86/kvm/vmx/x86_ops.h                    |   2 +-
 arch/x86/kvm/x86.c                            |   8 +-
 .../kvm/x86/userspace_msr_exit_test.c         |   8 +
 13 files changed, 426 insertions(+), 562 deletions(-)


base-commit: 61374cc145f4a56377eaf87c7409a97ec7a34041
-- 
2.50.0.rc0.642.g800a2b2222-goog