[GIT PULL] KVM: x86 changes for 6.13

[GIT PULL] KVM: x86 changes for 6.13

[Sean Christopherson]

AFAIK, there are no conflicts or dependencies with other architectures or
trees.

[GIT PULL] KVM: Generic changes for 6.13

[Sean Christopherson]

Please pull two changes that coincidentally happen to be related to vcpu->pid.

The following changes since commit 5cb1659f412041e4780f2e8ee49b2e03728a2ba6:

  Merge branch 'kvm-no-struct-page' into HEAD (2024-10-25 13:38:16 -0400)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-generic-6.13

for you to fetch changes up to 3e7f43188ee227bcf0f07f60a00f1fd1aca10e6a:

  KVM: Protect vCPU's "last run PID" with rwlock, not RCU (2024-10-30 14:41:22 -0700)

----------------------------------------------------------------
KVM generic changes for 6.13

 - Rework kvm_vcpu_on_spin() to use a single for-loop instead of making two
   partial poasses over "all" vCPUs.  Opportunistically expand the comment
   to better explain the motivation and logic.

 - Protect vcpu->pid accesses outside of vcpu->mutex with a rwlock instead
   of RCU, so that running a vCPU on a different task doesn't encounter
   long stalls due to having to wait for all CPUs become quiescent.

----------------------------------------------------------------
Sean Christopherson (3):
      KVM: Rework core loop of kvm_vcpu_on_spin() to use a single for-loop
      KVM: Return '0' directly when there's no task to yield to
      KVM: Protect vCPU's "last run PID" with rwlock, not RCU

 arch/arm64/include/asm/kvm_host.h |   2 +-
 include/linux/kvm_host.h          |   3 +-
 virt/kvm/kvm_main.c               | 143 ++++++++++++++++++++++----------------
 3 files changed, 86 insertions(+), 62 deletions(-)

[GIT PULL] KVM: x86: Misc changes for 6.13

[Sean Christopherson]

Please pull a variety of misc x86 changes.  The highlight is Maxim's
overhaul of the non-canonical logic to (try to) better follow hardware
behavior when LA57 is supported.

The STUFF_FEATURE_MSRS quirk might also be worth a second glance?

The following changes since commit 81983758430957d9a5cb3333fe324fd70cf63e7e:

  Linux 6.12-rc5 (2024-10-27 12:52:02 -1000)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-misc-6.13

for you to fetch changes up to a75b7bb46a83a2990f6b498251798930a19808d9:

  KVM: x86: Short-circuit all of kvm_apic_set_base() if MSR value is unchanged (2024-11-04 20:57:55 -0800)

----------------------------------------------------------------
KVM x86 misc changes for 6.13

 - Clean up and optimize KVM's handling of writes to MSR_IA32_APICBASE.

 - Quirk KVM's misguided behavior of initialized certain feature MSRs to
   their maximum supported feature set, which can result in KVM creating
   invalid vCPU state.  E.g. initializing PERF_CAPABILITIES to a non-zero
   value results in the vCPU having invalid state if userspace hides PDCM
   from the guest, which can lead to save/restore failures.

 - Fix KVM's handling of non-canonical checks for vCPUs that support LA57
   to better follow the "architecture", in quotes because the actual
   behavior is poorly documented.  E.g. most MSR writes and descriptor
   table loads ignore CR4.LA57 and operate purely on whether the CPU
   supports LA57.

 - Bypass the register cache when querying CPL from kvm_sched_out(), as
   filling the cache from IRQ context is generally unsafe, and harden the
   cache accessors to try to prevent similar issues from occuring in the
   future.

 - Advertise AMD_IBPB_RET to userspace, and fix a related bug where KVM
   over-advertises SPEC_CTRL when trying to support cross-vendor VMs.

 - Minor cleanups

----------------------------------------------------------------
Jim Mattson (2):
      KVM: x86: Advertise AMD_IBPB_RET to userspace
      KVM: x86: AMD's IBPB is not equivalent to Intel's IBPB

Kai Huang (2):
      KVM: x86: Fix a comment inside kvm_vcpu_update_apicv()
      KVM: x86: Fix a comment inside __kvm_set_or_clear_apicv_inhibit()

Maxim Levitsky (5):
      KVM: x86: drop x86.h include from cpuid.h
      KVM: x86: Route non-canonical checks in emulator through emulate_ops
      KVM: x86: Add X86EMUL_F_MSR and X86EMUL_F_DT_LOAD to aid canonical checks
      KVM: x86: model canonical checks more precisely
      KVM: nVMX: fix canonical check of vmcs12 HOST_RIP

Sean Christopherson (23):
      KVM: x86: Ensure vcpu->mode is loaded from memory in kvm_vcpu_exit_request()
      KVM: x86: Bypass register cache when querying CPL from kvm_sched_out()
      KVM: x86: Add lockdep-guarded asserts on register cache usage
      KVM: x86: Use '0' for guest RIP if PMI encounters protected guest state
      KVM: x86: Document an erratum in KVM_SET_VCPU_EVENTS on Intel CPUs
      KVM: x86: Co-locate initialization of feature MSRs in kvm_arch_vcpu_create()
      KVM: x86: Disallow changing MSR_PLATFORM_INFO after vCPU has run
      KVM: x86: Quirk initialization of feature MSRs to KVM's max configuration
      KVM: x86: Reject userspace attempts to access PERF_CAPABILITIES w/o PDCM
      KVM: VMX: Remove restriction that PMU version > 0 for PERF_CAPABILITIES
      KVM: x86: Reject userspace attempts to access ARCH_CAPABILITIES w/o support
      KVM: x86: Remove ordering check b/w MSR_PLATFORM_INFO and MISC_FEATURES_ENABLES
      KVM: selftests: Verify get/set PERF_CAPABILITIES w/o guest PDMC behavior
      KVM: selftests: Add a testcase for disabling feature MSRs init quirk
      KVM: x86: Short-circuit all kvm_lapic_set_base() if MSR value isn't changing
      KVM: x86: Drop superfluous kvm_lapic_set_base() call when setting APIC state
      KVM: x86: Get vcpu->arch.apic_base directly and drop kvm_get_apic_base()
      KVM: x86: Inline kvm_get_apic_mode() in lapic.h
      KVM: x86: Move kvm_set_apic_base() implementation to lapic.c (from x86.c)
      KVM: x86: Rename APIC base setters to better capture their relationship
      KVM: x86: Make kvm_recalculate_apic_map() local to lapic.c
      KVM: x86: Unpack msr_data structure prior to calling kvm_apic_set_base()
      KVM: x86: Short-circuit all of kvm_apic_set_base() if MSR value is unchanged

 Documentation/virt/kvm/api.rst                     |  22 ++++
 Documentation/virt/kvm/x86/errata.rst              |  12 +++
 arch/x86/include/asm/kvm-x86-ops.h                 |   1 +
 arch/x86/include/asm/kvm_host.h                    |   4 +-
 arch/x86/include/uapi/asm/kvm.h                    |   1 +
 arch/x86/kvm/cpuid.c                               |  12 ++-
 arch/x86/kvm/cpuid.h                               |   1 -
 arch/x86/kvm/emulate.c                             |  15 +--
 arch/x86/kvm/kvm_cache_regs.h                      |  17 +++
 arch/x86/kvm/kvm_emulate.h                         |   5 +
 arch/x86/kvm/lapic.c                               |  39 ++++++-
 arch/x86/kvm/lapic.h                               |  11 +-
 arch/x86/kvm/mmu.h                                 |   1 +
 arch/x86/kvm/mmu/mmu.c                             |   2 +-
 arch/x86/kvm/mtrr.c                                |   1 +
 arch/x86/kvm/svm/svm.c                             |   5 +-
 arch/x86/kvm/vmx/hyperv.c                          |   1 +
 arch/x86/kvm/vmx/main.c                            |   1 +
 arch/x86/kvm/vmx/nested.c                          |  35 +++---
 arch/x86/kvm/vmx/pmu_intel.c                       |   2 +-
 arch/x86/kvm/vmx/sgx.c                             |   5 +-
 arch/x86/kvm/vmx/vmx.c                             |  38 ++++---
 arch/x86/kvm/vmx/vmx.h                             |   1 +
 arch/x86/kvm/x86.c                                 | 120 ++++++++++-----------
 arch/x86/kvm/x86.h                                 |  48 ++++++++-
 tools/testing/selftests/kvm/Makefile               |   2 +-
 .../selftests/kvm/x86_64/feature_msrs_test.c       | 113 +++++++++++++++++++
 .../selftests/kvm/x86_64/get_msr_index_features.c  |  35 ------
 .../selftests/kvm/x86_64/platform_info_test.c      |   2 -
 .../selftests/kvm/x86_64/vmx_pmu_caps_test.c       |  23 ++++
 30 files changed, 419 insertions(+), 156 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/x86_64/feature_msrs_test.c
 delete mode 100644 tools/testing/selftests/kvm/x86_64/get_msr_index_features.c

Re: [GIT PULL] KVM: x86: Misc changes for 6.13

[Paolo Bonzini]

On Tue, Nov 12, 2024 at 8:40 PM Sean Christopherson <seanjc@google.com> wrote:
>
> Please pull a variety of misc x86 changes.  The highlight is Maxim's
> overhaul of the non-canonical logic to (try to) better follow hardware
> behavior when LA57 is supported.
>
> The STUFF_FEATURE_MSRS quirk might also be worth a second glance?

Yeah, it looks good but MSR_PLATFORM_INFO should be exposed as a
feature MSR (otherwise userspace has no clue what are the valid
values).  I'll send a patch.

Can I ask you for a review of the prepared bitmap series
(https://lore.kernel.org/kvm/20241108155056.332412-1-pbonzini@redhat.com/)
and possibly https://lore.kernel.org/kvm/20241108130737.126567-1-pbonzini@redhat.com/
(this one is not a huge deal though, as it's mostly deleting code)?

Paolo

[GIT PULL] KVM: x86: MMU changes for 6.13

[Sean Christopherson]

Aside from the A/D overhaul that you've already seen, the two highlights
are support for recovering TDP MMU huge pages in-place, and removal of KVM's
MMU shrinker (which IMO is long overdue).

The following changes since commit 5cb1659f412041e4780f2e8ee49b2e03728a2ba6:

  Merge branch 'kvm-no-struct-page' into HEAD (2024-10-25 13:38:16 -0400)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-mmu-6.13

for you to fetch changes up to 4cf20d42543cff8778f70b0c29def984098641a5:

  KVM: x86/mmu: Drop per-VM zapped_obsolete_pages list (2024-11-04 19:22:53 -0800)

----------------------------------------------------------------
KVM x86 MMU changes for 6.13

 - Cleanup KVM's handling of Accessed and Dirty bits to dedup code, improve
   documentation, harden against unexpected changes, and to simplify
   A/D-disabled MMUs by using the hardware-defined A/D bits to track if a
   PFN is Accessed and/or Dirty.

 - Elide TLB flushes when aging SPTEs, as has been done in x86's primary
   MMU for over 10 years.

 - Batch TLB flushes when zapping collapsible TDP MMU SPTEs, i.e. when
   dirty logging is toggled off, which reduces the time it takes to disable
   dirty logging by ~3x.

 - Recover huge pages in-place in the TDP MMU instead of zapping the SP
   and waiting until the page is re-accessed to create a huge mapping.
   Proactively installing huge pages can reduce vCPU jitter in extreme
   scenarios.

 - Remove support for (poorly) reclaiming page tables in shadow MMUs via
   the primary MMU's shrinker interface.

----------------------------------------------------------------
David Matlack (5):
      KVM: x86/mmu: Drop @max_level from kvm_mmu_max_mapping_level()
      KVM: x86/mmu: Batch TLB flushes when zapping collapsible TDP MMU SPTEs
      KVM: x86/mmu: Recover TDP MMU huge page mappings in-place instead of zapping
      KVM: x86/mmu: Rename make_huge_page_split_spte() to make_small_spte()
      KVM: x86/mmu: WARN if huge page recovery triggered during dirty logging

Sean Christopherson (21):
      KVM: x86/mmu: Flush remote TLBs iff MMU-writable flag is cleared from RO SPTE
      KVM: x86/mmu: Always set SPTE's dirty bit if it's created as writable
      KVM: x86/mmu: Fold all of make_spte()'s writable handling into one if-else
      KVM: x86/mmu: Don't force flush if SPTE update clears Accessed bit
      KVM: x86/mmu: Don't flush TLBs when clearing Dirty bit in shadow MMU
      KVM: x86/mmu: Drop ignored return value from kvm_tdp_mmu_clear_dirty_slot()
      KVM: x86/mmu: Fold mmu_spte_update_no_track() into mmu_spte_update()
      KVM: x86/mmu: WARN and flush if resolving a TDP MMU fault clears MMU-writable
      KVM: x86/mmu: Add a dedicated flag to track if A/D bits are globally enabled
      KVM: x86/mmu: Set shadow_accessed_mask for EPT even if A/D bits disabled
      KVM: x86/mmu: Set shadow_dirty_mask for EPT even if A/D bits disabled
      KVM: x86/mmu: Use Accessed bit even when _hardware_ A/D bits are disabled
      KVM: x86/mmu: Process only valid TDP MMU roots when aging a gfn range
      KVM: x86/mmu: Stop processing TDP MMU roots for test_age if young SPTE found
      KVM: x86/mmu: Dedup logic for detecting TLB flushes on leaf SPTE changes
      KVM: x86/mmu: Set Dirty bit for new SPTEs, even if _hardware_ A/D bits are disabled
      KVM: Allow arch code to elide TLB flushes when aging a young page
      KVM: x86: Don't emit TLB flushes when aging SPTEs for mmu_notifiers
      KVM: x86/mmu: Check yielded_gfn for forward progress iff resched is needed
      KVM: x86/mmu: Demote the WARN on yielded in xxx_cond_resched() to KVM_MMU_WARN_ON
      KVM: x86/mmu: Refactor TDP MMU iter need resched check

Vipin Sharma (2):
      KVM: x86/mmu: Remove KVM's MMU shrinker
      KVM: x86/mmu: Drop per-VM zapped_obsolete_pages list

 arch/x86/include/asm/kvm_host.h |   5 +-
 arch/x86/kvm/Kconfig            |   1 +
 arch/x86/kvm/mmu/mmu.c          | 201 ++++++-------------------------
 arch/x86/kvm/mmu/mmu_internal.h |   3 +-
 arch/x86/kvm/mmu/spte.c         |  99 +++++++++-------
 arch/x86/kvm/mmu/spte.h         |  76 ++++++------
 arch/x86/kvm/mmu/tdp_mmu.c      | 257 +++++++++++++++++++---------------------
 arch/x86/kvm/mmu/tdp_mmu.h      |   6 +-
 arch/x86/kvm/x86.c              |  18 ++-
 virt/kvm/Kconfig                |   4 +
 virt/kvm/kvm_main.c             |  20 +---
 11 files changed, 280 insertions(+), 410 deletions(-)

[GIT PULL] KVM: Selftests changes for 6.13

[Sean Christopherson]

Essentially AVX support, plus a few minor cleanups.

Far more noteworth is what's not in this pull request.  For 6.14, I want
to I want to land series with KVM-selftests-tree-wide impact: one that
changes^fixes the prototype for vcpu_get_reg(), and another that uses the
kernel's canonical $(ARCH) directory scheme instead of KVM selftests'
homebrewed $(ARCH_DIR).  My plan is to refresh both series after all arch
pull requests for 6.13 have landed, and then pester you incessantly to
apply them :-)

  https://lore.kernel.org/all/20241009154953.1073471-1-seanjc@google.com
  https://lore.kernel.org/all/20240826190116.145945-1-seanjc@google.com

The following changes since commit 81983758430957d9a5cb3333fe324fd70cf63e7e:

  Linux 6.12-rc5 (2024-10-27 12:52:02 -1000)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-selftests-6.13

for you to fetch changes up to 89f8869835e4da836bc60ab20568b7864706f94b:

  KVM: selftests: Ensure KVM supports AVX for SEV-ES VMSA FPU test (2024-11-01 09:26:37 -0700)

----------------------------------------------------------------
KVM selftests changes for 6.13

 - Enable XFAM-based features by default for all selftests VMs, which will
   allow removing the "no AVX" restriction.

----------------------------------------------------------------
Ba Jing (1):
      KVM: selftests: Remove unused macro in the hardware disable test

Jiapeng Chong (1):
      KVM: selftests: Use ARRAY_SIZE for array length

Sean Christopherson (10):
      KVM: selftests: Precisely mask off dynamic fields in CPUID test
      KVM: selftests: Mask off OSPKE and OSXSAVE when comparing CPUID entries
      KVM: selftests: Rework OSXSAVE CR4=>CPUID test to play nice with AVX insns
      KVM: selftests: Configure XCR0 to max supported value by default
      KVM: selftests: Verify XCR0 can be "downgraded" and "upgraded"
      KVM: selftests: Drop manual CR4.OSXSAVE enabling from CR4/CPUID sync test
      KVM: selftests: Drop manual XCR0 configuration from AMX test
      KVM: selftests: Drop manual XCR0 configuration from state test
      KVM: selftests: Drop manual XCR0 configuration from SEV smoke test
      KVM: selftests: Ensure KVM supports AVX for SEV-ES VMSA FPU test

 .../testing/selftests/kvm/hardware_disable_test.c  |  1 -
 .../selftests/kvm/include/x86_64/processor.h       |  5 ++
 tools/testing/selftests/kvm/lib/x86_64/processor.c | 24 ++++++++
 tools/testing/selftests/kvm/x86_64/amx_test.c      | 23 ++------
 tools/testing/selftests/kvm/x86_64/cpuid_test.c    | 67 ++++++++++++++--------
 .../selftests/kvm/x86_64/cr4_cpuid_sync_test.c     | 53 +++++++++++------
 tools/testing/selftests/kvm/x86_64/debug_regs.c    |  2 +-
 .../testing/selftests/kvm/x86_64/sev_smoke_test.c  | 19 ++----
 tools/testing/selftests/kvm/x86_64/state_test.c    |  5 --
 .../testing/selftests/kvm/x86_64/xcr0_cpuid_test.c | 11 +++-
 10 files changed, 123 insertions(+), 87 deletions(-)

[GIT PULL] KVM: VMX change for 6.13

[Sean Christopherson]

One lonely, comically small VMX change for 6.13.

The following changes since commit 5cb1659f412041e4780f2e8ee49b2e03728a2ba6:

  Merge branch 'kvm-no-struct-page' into HEAD (2024-10-25 13:38:16 -0400)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-vmx-6.13

for you to fetch changes up to bc17fccb37c8c100e3390e429e952330fd7cab1e:

  KVM: VMX: Remove the unused variable "gpa" in __invept() (2024-10-30 12:28:37 -0700)

----------------------------------------------------------------
KVM VMX change for 6.13

 - Remove __invept()'s unused @gpa param, which was left behind when KVM
   dropped code for invalidating a specific GPA (Intel never officially
   documented support for single-address INVEPT; presumably pre-production
   CPUs supported it at some point).

----------------------------------------------------------------
Yan Zhao (1):
      KVM: VMX: Remove the unused variable "gpa" in __invept()

 arch/x86/kvm/vmx/vmx.c     |  5 ++---
 arch/x86/kvm/vmx/vmx_ops.h | 16 ++++++++--------
 2 files changed, 10 insertions(+), 11 deletions(-)

Re: [GIT PULL] KVM: x86 changes for 6.13

[Paolo Bonzini]

Thanks, pulled.

Paolo

On Tue, Nov 12, 2024 at 8:33 PM Sean Christopherson <seanjc@google.com> wrote:
>
> AFAIK, there are no conflicts or dependencies with other architectures or
> trees.
>