[GIT PULL] KVM: Common changes for 6.12

[Sean Christopherson <seanjc@google.com>]

Fix a long-standing goof in the coalesced IO code, and a lurking bug in
kvm_clear_guest().

The following changes since commit 47ac09b91befbb6a235ab620c32af719f8208399:

  Linux 6.11-rc4 (2024-08-18 13:17:27 -0700)

are available in the Git repository at:

  https://github.com/kvm-x86/linux.git tags/kvm-x86-generic-6.12

for you to fetch changes up to 025dde582bbf31e7618f9283594ef5e2408e384b:

  KVM: Harden guest memory APIs against out-of-bounds accesses (2024-09-09 20:15:34 -0700)

----------------------------------------------------------------
KVK generic changes for 6.12:

 - Fix a bug that results in KVM prematurely exiting to userspace for coalesced
   MMIO/PIO in many cases, clean up the related code, and add a testcase.

 - Fix a bug in kvm_clear_guest() where it would trigger a buffer overflow _if_
   the gpa+len crosses a page boundary, which thankfully is guaranteed to not
   happen in the current code base.  Add WARNs in more helpers that read/write
   guest memory to detect similar bugs.

----------------------------------------------------------------
Ilias Stamatis (1):
      KVM: Fix coalesced_mmio_has_room() to avoid premature userspace exit

Sean Christopherson (4):
      KVM: selftests: Add a test for coalesced MMIO (and PIO on x86)
      KVM: Clean up coalesced MMIO ring full check
      KVM: Write the per-page "segment" when clearing (part of) a guest page
      KVM: Harden guest memory APIs against out-of-bounds accesses

 tools/testing/selftests/kvm/Makefile            |   3 +
 tools/testing/selftests/kvm/coalesced_io_test.c | 236 ++++++++++++++++++++++++
 tools/testing/selftests/kvm/include/kvm_util.h  |  26 +++
 virt/kvm/coalesced_mmio.c                       |  31 +---
 virt/kvm/kvm_main.c                             |  11 +-
 5 files changed, 283 insertions(+), 24 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/coalesced_io_test.c