[patch V2 00/17] entry: Provide generic implementation for host and guest entry/exit work

[Thomas Gleixner]

When working on a way to move out the posix cpu timer expiry out of the
timer interrupt context, I noticed that KVM is not handling pending task
work before entering a guest. A quick hack was to add that to the x86 KVM
handling loop. The discussion ended with a request to make this a generic
infrastructure possible with also moving the per arch implementations of
the enter from and return to user space handling generic.

  https://lore.kernel.org/r/89E42BCC-47A8-458B-B06A-D6A20D20512C@xxxxxxxxxxxxxx

The series implements the syscall enter/exit and the general exit to
userspace work handling along with the pre guest enter functionality.

Changes vs. RFC version:

  - Dropped ARM64 conversion as requested by ARM64 folks

  - Addressed various review comments (Peter, Andy, Mike, Paolo, Josh,
    Miroslav)

  - Picked up, fixed and completed Peter's patch which makes interrupt
    enable/disable symmetric in trap handlers

  - Completed the removal of irq disabling / irq tracing from low level
    ASM code

  - Moved KVM specific parts of the enter guest mode handling to KVM
    (Paolo)

The series is also available from git:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git WIP/core.entry

Thanks,

        tglx

RFC version: https://lore.kernel.org/r/20190919150314.054351477@xxxxxxxxxxxxx

---
 /Makefile                             |    3 
 arch/Kconfig                          |    3 
 arch/x86/Kconfig                      |    1 
 arch/x86/entry/calling.h              |   12 +
 arch/x86/entry/common.c               |  264 ++------------------------------
 arch/x86/entry/entry_32.S             |   41 ----
 arch/x86/entry/entry_64.S             |   32 ---
 arch/x86/entry/entry_64_compat.S      |   30 ---
 arch/x86/include/asm/irqflags.h       |    8 
 arch/x86/include/asm/paravirt.h       |    9 -
 arch/x86/include/asm/signal.h         |    1 
 arch/x86/include/asm/thread_info.h    |    9 -
 arch/x86/kernel/signal.c              |    2 
 arch/x86/kernel/traps.c               |   33 ++--
 arch/x86/kvm/x86.c                    |   17 --
 arch/x86/mm/fault.c                   |    7 
 b/arch/x86/include/asm/entry-common.h |  104 ++++++++++++
 b/arch/x86/kvm/Kconfig                |    1 
 b/include/linux/entry-common.h        |  280 ++++++++++++++++++++++++++++++++++
 b/kernel/entry/common.c               |  184 ++++++++++++++++++++++
 include/linux/kvm_host.h              |   64 +++++++
 kernel/Makefile                       |    1 
 virt/kvm/Kconfig                      |    3 
 23 files changed, 735 insertions(+), 374 deletions(-)