Merge tag 'kvmarm-6.2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 updates for 6.2

- Enable the per-vcpu dirty-ring tracking mechanism, together with an
  option to keep the good old dirty log around for pages that are
  dirtied by something other than a vcpu.

- Switch to the relaxed parallel fault handling, using RCU to delay
  page table reclaim and giving better performance under load.

- Relax the MTE ABI, allowing a VMM to use the MAP_SHARED mapping
  option, which multi-process VMMs such as crosvm rely on.

- Merge the pKVM shadow vcpu state tracking that allows the hypervisor
  to have its own view of a vcpu, keeping that state private.

- Add support for the PMUv3p5 architecture revision, bringing support
  for 64bit counters on systems that support it, and fix the
  no-quite-compliant CHAIN-ed counter support for the machines that
  actually exist out there.

- Fix a handful of minor issues around 52bit VA/PA support (64kB pages
  only) as a prefix of the oncoming support for 4kB and 16kB pages.

- Add/Enable/Fix a bunch of selftests covering memslots, breakpoints,
  stage-2 faults and access tracking. You name it, we got it, we
  probably broke it.

- Pick a small set of documentation and spelling fixes, because no
  good merge window would be complete without those.

As a side effect, this tag also drags:

- The 'kvmarm-fixes-6.1-3' tag as a dependency to the dirty-ring
  series

- A shared branch with the arm64 tree that repaints all the system
  registers to match the ARM ARM's naming, and resulting in
  interesting conflicts

1 files changed, 31 insertions, 10 deletions

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 9175d41e8081..fbb9a22030ba 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7418,8 +7418,9 @@ hibernation of the host; however the VMM needs to manually save/restore the
 tags as appropriate if the VM is migrated.
 
 When this capability is enabled all memory in memslots must be mapped as
-not-shareable (no MAP_SHARED), attempts to create a memslot with a
-MAP_SHARED mmap will result in an -EINVAL return.
+``MAP_ANONYMOUS`` or with a RAM-based file mapping (``tmpfs``, ``memfd``),
+attempts to create a memslot with an invalid mmap will result in an
+-EINVAL return.
 
 When enabled the VMM may make use of the ``KVM_ARM_MTE_COPY_TAGS`` ioctl to
 perform a bulk copy of tags to/from the guest.
@@ -7954,7 +7955,7 @@ regardless of what has actually been exposed through the CPUID leaf.
 8.29 KVM_CAP_DIRTY_LOG_RING/KVM_CAP_DIRTY_LOG_RING_ACQ_REL
 ----------------------------------------------------------
 
-:Architectures: x86
+:Architectures: x86, arm64
 :Parameters: args[0] - size of the dirty log ring
 
 KVM is capable of tracking dirty memory using ring buffers that are
@@ -8036,13 +8037,6 @@ flushing is done by the KVM_GET_DIRTY_LOG ioctl).  To achieve that, one
 needs to kick the vcpu out of KVM_RUN using a signal.  The resulting
 vmexit ensures that all dirty GFNs are flushed to the dirty rings.
 
-NOTE: the capability KVM_CAP_DIRTY_LOG_RING and the corresponding
-ioctl KVM_RESET_DIRTY_RINGS are mutual exclusive to the existing ioctls
-KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG.  After enabling
-KVM_CAP_DIRTY_LOG_RING with an acceptable dirty ring size, the virtual
-machine will switch to ring-buffer dirty page tracking and further
-KVM_GET_DIRTY_LOG or KVM_CLEAR_DIRTY_LOG ioctls will fail.
-
 NOTE: KVM_CAP_DIRTY_LOG_RING_ACQ_REL is the only capability that
 should be exposed by weakly ordered architecture, in order to indicate
 the additional memory ordering requirements imposed on userspace when
@@ -8051,6 +8045,33 @@ Architecture with TSO-like ordering (such as x86) are allowed to
 expose both KVM_CAP_DIRTY_LOG_RING and KVM_CAP_DIRTY_LOG_RING_ACQ_REL
 to userspace.
 
+After enabling the dirty rings, the userspace needs to detect the
+capability of KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP to see whether the
+ring structures can be backed by per-slot bitmaps. With this capability
+advertised, it means the architecture can dirty guest pages without
+vcpu/ring context, so that some of the dirty information will still be
+maintained in the bitmap structure. KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP
+can't be enabled if the capability of KVM_CAP_DIRTY_LOG_RING_ACQ_REL
+hasn't been enabled, or any memslot has been existing.
+
+Note that the bitmap here is only a backup of the ring structure. The
+use of the ring and bitmap combination is only beneficial if there is
+only a very small amount of memory that is dirtied out of vcpu/ring
+context. Otherwise, the stand-alone per-slot bitmap mechanism needs to
+be considered.
+
+To collect dirty bits in the backup bitmap, userspace can use the same
+KVM_GET_DIRTY_LOG ioctl. KVM_CLEAR_DIRTY_LOG isn't needed as long as all
+the generation of the dirty bits is done in a single pass. Collecting
+the dirty bitmap should be the very last thing that the VMM does before
+considering the state as complete. VMM needs to ensure that the dirty
+state is final and avoid missing dirty pages from another ioctl ordered
+after the bitmap collection.
+
+NOTE: One example of using the backup bitmap is saving arm64 vgic/its
+tables through KVM_DEV_ARM_{VGIC_GRP_CTRL, ITS_SAVE_TABLES} command on
+KVM device "kvm-arm-vgic-its" when dirty ring is enabled.
+
 8.30 KVM_CAP_XEN_HVM
 --------------------