[PATCH v2 00/10] KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications

[Vitaly Kuznetsov <vkuznets@redhat.com>]

Concerns were expressed around (ab)using #PF for KVM's async_pf mechanism,
it seems that re-using #PF exception for a PV mechanism wasn't a great
idea after all. The Grand Plan is to switch to using e.g. #VE for 'page
not present' events and normal APIC interrupts for 'page ready' events.
This series does the later.

Changes since v1:
- struct kvm_vcpu_pv_apf_data's fields renamed to 'flags' and 'token',
  comments added [Vivek Goyal]
- 'type1/2' names for APF events dropped from everywhere [Vivek Goyal]
- kvm_arch_can_inject_async_page_present() renamed to 
  kvm_arch_can_dequeue_async_page_present [Vivek Goyal]
- 'KVM: x86: deprecate KVM_ASYNC_PF_SEND_ALWAYS' patch added.

v1: https://lore.kernel.org/kvm/20200511164752.2158645-1-vkuznets@redhat.com/
QEMU patches for testing: https://github.com/vittyvk/qemu.git (async_pf2_v2 branch)

Vitaly Kuznetsov (10):
  Revert "KVM: async_pf: Fix #DF due to inject "Page not Present" and
    "Page Ready" exceptions simultaneously"
  KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info
  KVM: rename kvm_arch_can_inject_async_page_present() to
    kvm_arch_can_dequeue_async_page_present()
  KVM: introduce kvm_read_guest_offset_cached()
  KVM: x86: interrupt based APF 'page ready' event delivery
  KVM: x86: acknowledgment mechanism for async pf page ready
    notifications
  KVM: x86: announce KVM_FEATURE_ASYNC_PF_INT
  KVM: x86: Switch KVM guest to using interrupts for page ready APF
    delivery
  KVM: x86: drop KVM_PV_REASON_PAGE_READY case from
    kvm_handle_page_fault()
  KVM: x86: deprecate KVM_ASYNC_PF_SEND_ALWAYS

 Documentation/virt/kvm/cpuid.rst     |   6 ++
 Documentation/virt/kvm/msr.rst       | 120 +++++++++++++++------
 arch/s390/include/asm/kvm_host.h     |   4 +-
 arch/s390/kvm/kvm-s390.c             |   2 +-
 arch/x86/entry/entry_32.S            |   5 +
 arch/x86/entry/entry_64.S            |   5 +
 arch/x86/include/asm/hardirq.h       |   3 +
 arch/x86/include/asm/irq_vectors.h   |   6 +-
 arch/x86/include/asm/kvm_host.h      |  12 ++-
 arch/x86/include/asm/kvm_para.h      |  10 +-
 arch/x86/include/uapi/asm/kvm_para.h |  19 +++-
 arch/x86/kernel/irq.c                |   9 ++
 arch/x86/kernel/kvm.c                |  62 +++++++----
 arch/x86/kvm/cpuid.c                 |   3 +-
 arch/x86/kvm/mmu/mmu.c               |  19 ++--
 arch/x86/kvm/svm/nested.c            |   2 +-
 arch/x86/kvm/svm/svm.c               |   3 +-
 arch/x86/kvm/vmx/nested.c            |   2 +-
 arch/x86/kvm/vmx/vmx.c               |   5 +-
 arch/x86/kvm/x86.c                   | 149 ++++++++++++++++++---------
 include/linux/kvm_host.h             |   3 +
 include/uapi/linux/kvm.h             |   1 +
 virt/kvm/async_pf.c                  |  12 ++-
 virt/kvm/kvm_main.c                  |  19 +++-
 24 files changed, 344 insertions(+), 137 deletions(-)

-- 
2.25.4