When operating on an unpinned pagetable (ie, one under construction or
destruction), it isn't necessary to use a hypercall to update a
pud/pmd entry. Jan Beulich observed that a similar optimisation
avoided many thousands of hypercalls while doing a kernel build.
One tricky part is that early in the kernel boot there's no page
structure, so we can't check to see if the page is pinned. In that
case, we just always use the hypercall.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Jan Beulich <jbeulich@novell.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Xen save/restore depends on CONFIG_PM_SLEEP being set for device_power_up/down.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-tip testing found the following build breakage:
drivers/built-in.o: In function `xen_suspend':
manage.c:(.text+0x4390f): undefined reference to `xen_console_resume'
with this config:
http://redhat.com/~mingo/misc/config-Thu_May_29_09_23_16_CEST_2008.bad
i have bisected it down to:
| commit 0e91398f2a
| Author: Jeremy Fitzhardinge <jeremy@goop.org>
| Date: Mon May 26 23:31:27 2008 +0100
|
| xen: implement save/restore
the problem is that drivers/xen/manage.c is built unconditionally if
CONFIG_XEN is enabled and makes use of xen_suspend(), but
drivers/char/hvc_xen.c, where the xen_suspend() method is implemented,
is only build if CONFIG_HVC_XEN=y as well.
i have solved this by providing a NOP implementation for xen_suspend()
in the !CONFIG_HVC_XEN case.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-tip tree auto-testing found the following early bootup hang:
-------------->
get_memcfg_from_srat: assigning address to rsdp
RSD PTR v0 [Nvidia]
BUG: Int 14: CR2 ffd00040
EDI 8092fbfe ESI ffd00040 EBP 80b0aee8 ESP 80b0aed0
EBX 000f76f0 EDX 0000000e ECX 00000003 EAX ffd00040
err 00000000 EIP 802c055a CS 00000060 flg 00010006
Stack: ffd00040 80bc78d0 80b0af6c 80b1dbfe 8093d8ba 00000008 80b42810 80b4ddb4
80b42842 00000000 80b0af1c 801079c8 808e724e 00000000 80b42871 802c0531
00000100 00000000 0003fff0 80b0af40 80129999 00040100 00040100 00000000
Pid: 0, comm: swapper Not tainted 2.6.26-rc4-sched-devel.git #570
[<802c055a>] ? strncmp+0x11/0x25
[<80b1dbfe>] ? get_memcfg_from_srat+0xb4/0x568
[<801079c8>] ? mcount_call+0x5/0x9
[<802c0531>] ? strcmp+0xa/0x22
[<80129999>] ? printk+0x38/0x3a
[<80129999>] ? printk+0x38/0x3a
[<8011b122>] ? memory_present+0x66/0x6f
[<80b216b4>] ? setup_memory+0x13/0x40c
[<80b16b47>] ? propagate_e820_map+0x80/0x97
[<80b1622a>] ? setup_arch+0x248/0x477
[<80129999>] ? printk+0x38/0x3a
[<80b11759>] ? start_kernel+0x6e/0x2eb
[<80b110fc>] ? i386_start_kernel+0xeb/0xf2
=======================
<------
with this config:
http://redhat.com/~mingo/misc/config-Wed_May_28_01_33_33_CEST_2008.bad
The thing is, the crash makes little sense at first sight. We crash on a
benign-looking printk. The code around it got changed in -tip but
checking those topic branches individually did not reproduce the bug.
Bisection led to this commit:
| d5edbc1f75 is first bad commit
| commit d5edbc1f75
| Author: Jeremy Fitzhardinge <jeremy@goop.org>
| Date: Mon May 26 23:31:22 2008 +0100
|
| xen: add p2m mfn_list_list
Which is somewhat surprising, as on native hardware Xen client side
should have little to no side-effects.
After some head scratching, it turns out the following happened:
randconfig enabled the following Xen options:
CONFIG_XEN=y
CONFIG_XEN_MAX_DOMAIN_MEMORY=8
# CONFIG_XEN_BLKDEV_FRONTEND is not set
# CONFIG_XEN_NETDEV_FRONTEND is not set
CONFIG_HVC_XEN=y
# CONFIG_XEN_BALLOON is not set
which activated this piece of code in arch/x86/xen/mmu.c:
> @@ -69,6 +69,13 @@
> __attribute__((section(".data.page_aligned"))) =
> { [ 0 ... TOP_ENTRIES - 1] = &p2m_missing[0] };
>
> +/* Arrays of p2m arrays expressed in mfns used for save/restore */
> +static unsigned long p2m_top_mfn[TOP_ENTRIES]
> + __attribute__((section(".bss.page_aligned")));
> +
> +static unsigned long p2m_top_mfn_list[TOP_ENTRIES / P2M_ENTRIES_PER_PAGE]
> + __attribute__((section(".bss.page_aligned")));
The problem is, you must only put variables into .bss.page_aligned that
have a _size_ that is _exactly_ page aligned. In this case the size of
p2m_top_mfn_list is not page aligned:
80b8d000 b p2m_top_mfn
80b8f000 b p2m_top_mfn_list
80b8f008 b softirq_stack
80b97008 b hardirq_stack
80b9f008 b bm_pte
So all subsequent variables get unaligned which, depending on luck,
breaks the kernel in various funny ways. In this case what killed the
kernel first was the misaligned bootmap pte page, resulting in that
creative crash above.
Anyway, this was a fun bug to track down :-)
I think the moral is that .bss.page_aligned is a dangerous construct in
its current form, and the symptoms of breakage are very non-trivial, so
i think we need build-time checks to make sure all symbols in
.bss.page_aligned are truly page aligned.
The Xen fix below gets the kernel booting again.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Hook into the device model to make sure that timekeeping's resume handler
is called. This deals with our clocksource's non-monotonicity over the
save/restore. Explicitly call clock_has_changed() to make sure that
all the timers get retriggered properly.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This patch implements Xen save/restore and migration.
Saving is triggered via xenbus, which is polled in
drivers/xen/manage.c. When a suspend request comes in, the kernel
prepares itself for saving by:
1 - Freeze all processes. This is primarily to prevent any
partially-completed pagetable updates from confusing the suspend
process. If CONFIG_PREEMPT isn't defined, then this isn't necessary.
2 - Suspend xenbus and other devices
3 - Stop_machine, to make sure all the other vcpus are quiescent. The
Xen tools require the domain to run its save off vcpu0.
4 - Within the stop_machine state, it pins any unpinned pgds (under
construction or destruction), performs canonicalizes various other
pieces of state (mostly converting mfns to pfns), and finally
5 - Suspend the domain
Restore reverses the steps used to save the domain, ending when all
the frozen processes are thawed.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When restoring, rebind the existing xenbus irq to the new xenbus event
channel. (It turns out in practice that this is always the same, and
is never updated on restore. That's a bug, but Xeno-linux has been
like this for a long time, so it can't really be fixed.)
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add code to:
1. Deal with the console page being canonicalized. During save, the
console's mfn in the start_info structure is canonicalized to a pfn.
In order to deal with that, we always use a copy of the pfn and
indirect off that all the time. However, we fall back to using the
mfn if the pfn hasn't been initialized yet.
2. Restore the console event channel, and rebind it to the existing irq.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Rearrange the tests in unbind_from_irq() so that we can still unbind
an irq even if the underlying event channel is bad. This allows a
device driver to shuffle its irqs on save/restore before the
underlying event channels have been fixed up.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add rebind_evtchn_irq(), which will rebind an device driver's existing
irq to a new event channel on restore. Since the new event channel
will be masked and bound to vcpu0, we update the state accordingly and
unmask the irq once everything is set up.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When saving a domain, the Xen tools need to remap all our mfns to
portable pfns. In order to remap our p2m table, it needs to know
where all its pages are, so maintain the references to the p2m table
for it to use.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Rename dummy_shared_info to xen_dummy_shared_info and make it
non-static, in anticipation of users outside of enlighten.c
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When using sparsemem and memory hotplug, the kernel's pseudo-physical
address space can be discontigious. Previously this was dealt with by
having the upper parts of the radix tree stubbed off. Unfortunately,
this is incompatible with save/restore, which requires a complete p2m
table.
The solution is to have a special distinguished all-invalid p2m leaf
page, which we can point all the hole areas at. This allows the tools
to see a complete p2m table, but it only costs a page for all memory
holes.
It also simplifies the code since it removes a few special cases.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add a config option to set the max size of a Xen domain. This is used
to scale the size of the physical-to-machine array; it ends up using
around 1 page/GByte, so there's no reason to be very restrictive.
For a 32-bit guest, the default value of 8GB is probably sufficient;
there's not much point in giving a 32-bit machine much more memory
than that.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
We now support the use of memory hotplug, so the physical to machine
page mapping structure must be dynamic. This is implemented as a
two-level radix tree structure, which allows us to efficiently
incrementally allocate memory for the p2m table as new pages are
added.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Make the needlessly global balloon_set_new_target() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Acked-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Make sure resched interrupts appear in /proc/interrupts in the proper
place.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add xen handles realted definitions for xen memory which ia64/xen needs.
Pointer argumsnts for ia64/xen hypercall are passed in pseudo physical
address (guest physical address) so that it is required to convert
guest kernel virtual address into pseudo physical address.
The xen guest handle represents such arguments.
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
fix compilation error of ballon driver on ia64.
extent_start member is pointer argument. On x86 pointer argument for
xen hypercall is passed as virtual address.
On the other hand, ia64 and ppc, pointer argument is passed in pseudo
physical address. (guest physicall address.)
So they must be passed as handle and convert right before issuing hypercall.
CC drivers/xen/balloon.o
linux-2.6-x86/drivers/xen/balloon.c: In function 'increase_reservation':
linux-2.6-x86/drivers/xen/balloon.c:228: error: incompatible types in assignment
linux-2.6-x86/drivers/xen/balloon.c: In function 'decrease_reservation':
linux-2.6-x86/drivers/xen/balloon.c:324: error: incompatible types in assignment
linux-2.6-x86/drivers/xen/balloon.c: In function 'dealloc_pte_fn':
linux-2.6-x86/drivers/xen/balloon.c:486: error: incompatible types in assignment
linux-2.6-x86/drivers/xen/balloon.c: In function 'alloc_empty_pages_and_pagevec':
linux-2.6-x86/drivers/xen/balloon.c:522: error: incompatible types in assignment
make[2]: *** [drivers/xen/balloon.o] Error 1
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
move arch/x86/xen/manage.c under drivers/xen/to share codes
with x86 and ia64.
ia64/xen also uses manage.c
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
For some perverse reason, if you call add_preferred_console() it prevents
setup_early_printk() from successfully enabling the boot console -
unless you make it a preferred console too...
Also, make xenboot console output distinct from normal console output,
since it gets repeated when the console handover happens, and the
duplicated output is confusing without disambiguation.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Markus Armbruster <armbru@redhat.com>
Cc: Gerd Hoffmann <kraxel@redhat.com>
The pvfb backend indicates dynamic mode support by creating node
feature_resize with a non-zero value in its xenstore directory.
xen-fbfront sends a resize notification event on mode change. Fully
backwards compatible both ways.
Framebuffer size and initial resolution can be controlled through
kernel parameter xen_fbfront.video. The backend enforces a separate
size limit, which it advertises in node videoram in its xenstore
directory.
xen-kbdfront gets the maximum screen resolution from nodes width and
height in the backend's xenstore directory instead of hardcoding it.
Additional goodie: support for larger framebuffers (512M on a 64-bit
system with 4K pages).
Changing the number of bits per pixels dynamically is not supported,
yet.
Ported from
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/92f7b3144f41http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/bfc040135633
Signed-off-by: Pat Campbell <plc@novell.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This isn't a security flaw (the backend can see all our memory
anyway). But it's the right thing to do all the same.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
These are mostly for completeness and consistency with the other
frontends, as PVFB is typically compiled in rather than a module.
Derived from
http://xenbits.xensource.com/linux-2.6.18-xen.hg?rev/5e294e29a43e
While there, add module descriptions.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Without console= arguments on the kernel command line, the first
console to register becomes enabled and the preferred console (the one
behind /dev/console). This is normally tty (assuming
CONFIG_VT_CONSOLE is enabled, which it commonly is).
This is okay as long tty is a useful console. But unless we have the
PV framebuffer, and it is enabled for this domain, tty0 in domU is
merely a dummy. In that case, we want the preferred console to be the
Xen console hvc0, and we want it without having to fiddle with the
kernel command line. Commit b8c2d3dfbc
did that for us.
Since we now have the PV framebuffer, we want to enable and prefer tty
again, but only when PVFB is enabled. But even then we still want to
enable the Xen console as well.
Problem: when tty registers, we can't yet know whether the PVFB is
enabled. By the time we can know (xenstore is up), the console setup
game is over.
Solution: enable console tty by default, but keep hvc as the preferred
console. Change the preferred console to tty when PVFB probes
successfully, unless we've been given console kernel parameters.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add pte_flags() to extract the flags from a pte. This is a special
case of pte_val() which is only guaranteed to return the pte's flags
correctly; the page number may be corrupted or missing.
The intent is to allow paravirt implementations to return pte flags
without having to do any translation of the page number (most notably,
Xen).
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When enabling interrupts, we don't need to worry about preemption,
because we either enter with interrupts disabled - so no preemption -
or the caller is confused and is re-enabling interrupts on some
indeterminate processor.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The guest can legitimately change things like cr4.OSFXSR and
OSXMMEXCPT, so let it.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Use the new sched_op hypercall, mainly because xenner doesn't support
the old one.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Xen will trap and emulate clts, but its better to use a hypercall.
Also, xenner doesn't handle clts.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
When using "earlyprintk=xen", also write the console output to the raw
debug console. This will appear on dom0's console if the hypervisor
has been compiled to allow it.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add a couple of functions which can write directly to the Xen console
for debugging. This output ends up on the host's dom0 console
(assuming it allows the domain to write there).
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Non-PAE operation has been deprecated in Xen for a while, and is
rarely tested or used. xen-unstable has now officially dropped
non-PAE support. Since Xen/pvops' non-PAE support has also been
broken for a while, we may as well completely drop it altogether.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Whether we sidestep it in init/main.c or not, such situations
will arise again; compiler does generate calls of strcat()
on optimizations, so we really ought to have an out-of-line
version...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
... and we have few enough places using the latter to make it
simpler to do search and replace...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcpy() from userland pointer is a Bad Thing(tm)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fallout from commit 46d7b522eb ("uml: move
hppfs_kern.c to hppfs.c")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
