This bug has been there since day 1; addresses in the top guest physical
page weren't considered valid.  You could map that page (the check in
check_gpte() is correct), but if a guest tried to put a pagetable there
we'd check that address manually when walking it, and kill the guest.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull virtio updates from Rusty Russell:
 "Some virtio internal cleanups, a new virtio device "virtio input", and
  a change to allow the legacy virtio balloon.

  Most excitingly, some lguest work! No seriously, I got some cleanup
  patches"

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux:
  virtio: drop virtio_device_is_legacy_only
  virtio_pci: support non-legacy balloon devices
  virtio_mmio: support non-legacy balloon devices
  virtio_ccw: support non-legacy balloon devices
  virtio: balloon might not be a legacy device
  virtio_balloon: transitional interface
  virtio_ring: Update weak barriers to use dma_wmb/rmb
  virtio_pci_modern: switch to type-safe io accessors
  virtio_pci_modern: type-safe io accessors
  lguest: handle traps on the "interrupt suppressed" iret instruction.
  virtio: drop a useless config read
  virtio_config: reorder functions
  Add virtio-input driver.
  lguest: suppress interrupts for single insn, not range.
  lguest: simplify lguest_iret
  lguest: rename i386_head.S in the comments
  lguest: explicitly set miscdevice's private_data NULL
  lguest: fix pending interrupt test.

Since commit 8e7094694396 ("lguest: add a dummy PCI host bridge.")
lguest uses PCI, but it needs you to frob the ports directly.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Lguest's "iret" is non-atomic, as it needs to restore the interrupt
state before the real iret (the guest can't actually suppress
interrupts).  For this reason, the host discards an interrupt if it
occurs in this (1-instruction) window.

We can do better, by emulating the iret execution, then immediately
setting up the interrupt handler.  In fact, we don't need to do much,
as emulating the iret and setting up th stack for the interrupt handler
basically cancel each other out.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

The last patch reduced our interrupt-suppression region to one address,
so simplify the code somewhat.

Also, remove the obsolete undefined instruction ranges and the comment
which refers to lguest_guest.S instead of head_32.S.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

There is a proposed change to the miscdevice's behaviour on open(). Currently
file->private_data stays NULL, but only because we don't have an open-entry in
struct file_operations.

This may change so that private_data, more consistently, is always set to
struct miscdevice, not only *if* the driver has it's own open() routine and
fops-entry, see https://lkml.org/lkml/2014/12/4/939 and commit
94e4fe2cab3d43b3ba7c3f721743006a8c9d913a

In short: If we rely on file->private_data being NULL, we should ensure
it is NULL ourselves.

Signed-off-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

Pull virtio updates from Rusty Russell:
 "OK, this has the big virtio 1.0 implementation, as specified by OASIS.

  On top of tht is the major rework of lguest, to use PCI and virtio
  1.0, to double-check the implementation.

  Then comes the inevitable fixes and cleanups from that work"

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (80 commits)
  virtio: don't set VIRTIO_CONFIG_S_DRIVER_OK twice.
  virtio_net: unconditionally define struct virtio_net_hdr_v1.
  tools/lguest: don't use legacy definitions for net device in example launcher.
  virtio: Don't expose legacy net features when VIRTIO_NET_NO_LEGACY defined.
  tools/lguest: use common error macros in the example launcher.
  tools/lguest: give virtqueues names for better error messages
  tools/lguest: more documentation and checking of virtio 1.0 compliance.
  lguest: don't look in console features to find emerg_wr.
  tools/lguest: don't start devices until DRIVER_OK status set.
  tools/lguest: handle indirect partway through chain.
  tools/lguest: insert driver references from the 1.0 spec (4.1 Virtio Over PCI)
  tools/lguest: insert device references from the 1.0 spec (4.1 Virtio Over PCI)
  tools/lguest: rename virtio_pci_cfg_cap field to match spec.
  tools/lguest: fix features_accepted logic in example launcher.
  tools/lguest: handle device reset correctly in example launcher.
  virtual: Documentation: simplify and generalize paravirt_ops.txt
  lguest: remove NOTIFY call and eventfd facility.
  lguest: remove NOTIFY facility from demonstration launcher.
  lguest: use the PCI console device's emerg_wr for early boot messages.
  lguest: always put console in PCI slot #1.
  ...

Disappointing, as this was kind of neat (especially getting to use RCU
to manage the address -> eventfd mapping).  But now the devices are PCI
handled in userspace, we get rid of both the NOTIFY hypercall and
the interface to connect an eventfd.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

The demonstration launcher now uses PCI entirely.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

This lets us implement PCI.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>