Update the hvc driver to use the OPAL irqchip if made available by the
running firmware. If it is not present, the driver falls back to the
existing OPAL event number.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Commit 2def86a7200c ("hvc: Convert to using interrupts instead of opal
events") enabled the use of interrupts in the hvc_driver for OPAL
platforms. However on machines with more than one hvc console, any
console after the first will fail to register an interrupt handler in
notifier_add_irq() since all consoles share the same IRQ number but do
not set the IRQF_SHARED flag:

  genirq: Flags mismatch irq 31. 00000000 (hvc_console) vs. 00000000 (hvc_console)
  hvc_open: request_irq failed with rc -16.

This error propagates up to hvc_open() and the console is closed, but
OPAL will still generate interrupts that are not handled, leading to
rcu_sched stall warnings.

Set IRQF_SHARED when calling request_irq(), allowing additional consoles
to start properly. This is only set for consoles handled by
hvc_opal_probe(), leaving other types unaffected.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

If ->get_char() returns a negative error code and that can mean that
"ch" is uninitialized.  The callers of this function expect NO_POLL_CHAR
on error so let's return that.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Abstract TTY_THROTTLED bit tests with tty_throttled().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Pull xen updates from David Vrabel:
 "Features and fixes for 4.6:

  - Make earlyprintk=xen work for HVM guests

  - Remove module support for things never built as modules"

* tag 'for-linus-4.6-rc0-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  drivers/xen: make platform-pci.c explicitly non-modular
  drivers/xen: make sys-hypervisor.c explicitly non-modular
  drivers/xen: make xenbus_dev_[front/back]end explicitly non-modular
  drivers/xen: make [xen-]ballon explicitly non-modular
  xen: audit usages of module.h ; remove unnecessary instances
  xen/x86: Drop mode-selecting ifdefs in startup_xen()
  xen/x86: Zero out .bss for PV guests
  hvc_xen: make early_printk work with HVM guests
  hvc_xen: fix xenboot for DomUs
  hvc_xen: add earlycon support

Refactor the existing code in xen_raw_console_write to get the generic
early_printk console work with HVM guests.

Take the opportunity to replace the outb loop with a single outsb call
to reduce the number of vmexit.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

The xenboot early console has been partially broken for DomU for a long
time: the output would only go to the hypervisor via hypercall
(HYPERVISOR_console_io), while it wouldn't actually go to the DomU
console. The reason is that domU_write_console would return early as no
xencons structs are configured for it.

Add an appropriate xencons struct for xenboot from the xenboot setup
callback.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Introduce EARLYCON support in hvc_xen, useful for early debugging on arm
and arm64, where xen early_printk is not available.

It is different from xenboot_write_console on x86 in two ways:

- it does not return if !xen_pv_domain(), not only because ARM guests
  are xen_hvm_domain(), but also because we want to capture all the
  early boot messages, before xen support is discovered
- it does not try to print to the domU console at all, because xen
  support will only be discovered at a later point

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

These hv_ops structures are never modified, so declare them as const.  Most
were const already.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

xencons_disconnect_backend() is only called from xen_console_remove(),
which is conditionally compiled, so we get a harmless warning when
CONFIG_HVC_XEN_FRONTEND is unset:

hvc/hvc_xen.c:350:12: error: 'xen_console_remove' defined but not used [-Werror=unused-function]

This moves the function down into the same #ifdef section to silence
the warning.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>