I've been doing this for years, and akpm picked me up on it about 12
months ago. lguest partly serves as example code, so let's do it Right.
Also, remove two unused fields in struct vblk_info in the example launcher.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Every so often, after code shuffles, I need to go through and unbitrot
the Lguest Journey (see drivers/lguest/README). Since we now use RCU in
a simple form in one place I took the opportunity to expand that explanation.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
I don't really notice it (except to begrudge the extra vertical
space), but Ingo does. And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
"new" was freed and then dereferenced. Also the return value wasn't being
used so I modified the caller as well.
Compile tested only. Found by smatch (http://repo.or.cz/w/smatch.git).
regards,
dan carpenter
Signed-off-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Change the eventfd interface to de-couple the eventfd memory context, from
the file pointer instance.
Without such change, there is no clean way to racely free handle the
POLLHUP event sent when the last instance of the file* goes away. Also,
now the internal eventfd APIs are using the eventfd context instead of the
file*.
This patch is required by KVM's IRQfd code, which is still under
development.
Signed-off-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Gregory Haskins <ghaskins@novell.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest: (31 commits)
lguest: add support for indirect ring entries
lguest: suppress notifications in example Launcher
lguest: try to batch interrupts on network receive
lguest: avoid sending interrupts to Guest when no activity occurs.
lguest: implement deferred interrupts in example Launcher
lguest: remove obsolete LHREQ_BREAK call
lguest: have example Launcher service all devices in separate threads
lguest: use eventfds for device notification
eventfd: export eventfd_signal and eventfd_fget for lguest
lguest: allow any process to send interrupts
lguest: PAE fixes
lguest: PAE support
lguest: Add support for kvm_hypercall4()
lguest: replace hypercall name LHCALL_SET_PMD with LHCALL_SET_PGD
lguest: use native_set_* macros, which properly handle 64-bit entries when PAE is activated
lguest: map switcher with executable page table entries
lguest: fix writev returning short on console output
lguest: clean up length-used value in example launcher
lguest: Segment selectors are 16-bit long. Fix lg_cpu.ss1 definition.
lguest: beyond ARRAY_SIZE of cpu->arch.gdt
...
We no longer need an efficient mechanism to force the Guest back into
host userspace, as each device is serviced without bothering the main
Guest process (aka. the Launcher).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Currently, when a Guest wants to perform I/O it calls LHCALL_NOTIFY with
an address: the main Launcher process returns with this address, and figures
out what device to run.
A far nicer model is to let processes bind an eventfd to an address: if we
find one, we simply signal the eventfd.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Davide Libenzi <davidel@xmailserver.org>
We currently only allow the Launcher process to send interrupts, but it
as we already send interrupts from the hrtimer, it's a simple matter of
extracting that code into a common set_interrupt routine.
As we switch to a thread per virtqueue, this avoids a bottleneck through the
main Launcher process.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
1) j wasn't initialized in setup_pagetables, so they weren't set up for me
causing immediate guest crashes.
2) gpte_addr should not re-read the pmd from the Guest. Especially
not BUG_ON() based on the value. If we ever supported SMP guests,
they could trigger that. And the Launcher could also trigger it
(tho currently root-only).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This version requires that host and guest have the same PAE status.
NX cap is not offered to the guest, yet.
Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
replace LHCALL_SET_PMD with LHCALL_SET_PGD hypercall name
(That's really what it is, and the confusion gets worse with PAE support)
Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Reported-by: Jeremy Fitzhardinge <jeremy@goop.org>
Some cleanups and replace direct assignment with native_set_* macros which properly handle 64-bit entries when PAE is activated
Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
If GDT_ENTRIES were every > 256, this could become a problem.
Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
lguest never checked for pending interrupts when enabling interrupts, and
things still worked. However, it makes a significant difference to TCP
performance, so it's time we fixed it by introducing a pending_irq flag
and checking it on irq_restore and irq_enable.
These two routines are now too big to patch into the 8/10 bytes
patch space, so we drop that code.
Note: The high latency on interrupt delivery had a very curious
effect: once everything else was optimized, networking without GSO was
faster than networking with GSO, since more interrupts were sent and
hence a greater chance of one getting through to the Guest!
Note2: (Almost) Closing the same loophole for iret doesn't have any
measurable effect, so I'm leaving that patch for the moment.
Before:
1GB tcpblast Guest->Host: 30.7 seconds
1GB tcpblast Guest->Host (no GSO): 76.0 seconds
After:
1GB tcpblast Guest->Host: 6.8 seconds
1GB tcpblast Guest->Host (no GSO): 27.8 seconds
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When the Guest does the LHCALL_HALT hypercall, we go to sleep, expecting
that a timer or the Waker will wake_up_process() us.
But we do it in a stupid way, leaving a classic missing wakeup race.
So split maybe_do_interrupt() into interrupt_pending() and
try_deliver_interrupt(), and check maybe_do_interrupt() and the
"break_out" flag before calling schedule.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
The Launcher could be inside the Guest on another CPU; wake_up_process
will do nothing because it is "running". kick_process will knock it
back into our kernel in this case, otherwise we'll miss it until the
next guest exit.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This replaces find_vq/del_vq with find_vqs/del_vqs virtio operations,
and updates all drivers. This is needed for MSI support, because MSI
needs to know the total number of vectors upfront.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (+ lguest/9p compile fixes)
Add a linked list of all virtqueues for a virtio device: this helps for
debugging and is also needed for upcoming interface change.
Also, add a "name" field for clearer debug messages.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
When KVM is loaded, and hence VT set up, the vmcall instruction in an
lguest guest causes a #GP, not #UD.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes guest crash 'lguest: bad read address 0x4800000 len 256'
The new per-cpu allocator ends up handing a non-linear address to
write_gdt_entry. We do __pa() on it, and hand it to the host, which
kills us.
I've long wanted to make the hypercall "LOAD_GDT_ENTRY" to match the IDT
code, but had no pressing reason until now.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: lguest@ozlabs.org
Typical message: 'lguest: unhandled trap 6 at 0x418726 (0x0)'
vmlinux guests were broken by 4cd8b5e2a1
'lguest: use KVM hypercalls', which rewrites guest text from kvm hypercalls
to trap 31.
The Launcher mmaps the kernel image. The Guest executes and
immediately faults in the first text page (read-only). Then it hits a
hypercall, and we rewrite that hypercall, causing a copy-on-write.
But the Guest pagetables still refer to the old page: we fault again,
but as Host we see the hypercall already rewritten, and pass the fault
back to the Guest. The Guest hasn't set up an IDT yet, so we kill it.
This doesn't happen with bzImages: they unpack themselves and so the
text pages are already read-write.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Tested-by: Patrick McHardy <kaber@trash.net>
Impact: clean up
Rusty told me, some time ago, that he had become a fan of "bool".
So, here are some replacements.
Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Impact: cleanup
This patch allow us to use KVM hypercalls
Signed-off-by: Matias Zabaljauregui <zabaljauregui at gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Impact: fix crash on misbehaving guest
gpte_addr() contains a BUG_ON(), insisting that the present flag is
set. We need to return before we call it if that isn't the case.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org
Impact: remove lots of lguest boot WARN_ON() when CONFIG_SPARSE_IRQ=y
We now need to call irq_to_desc_alloc_cpu() before
set_irq_chip_and_handler_name(), but we can't do that from init_IRQ (no
kmalloc available).
So do it as we use interrupts instead. Also means we only alloc for
irqs we use, which was the intent of CONFIG_SPARSE_IRQ anyway.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Impact: remove unused/broken code
The Voyager subarch last built successfully on the v2.6.26 kernel
and has been stale since then and does not build on the v2.6.27,
v2.6.28 and v2.6.29-rc5 kernels.
No actual users beyond the maintainer reported this breakage.
Patches were sent and most of the fixes were accepted but the
discussion around how to do a few remaining issues cleanly
fizzled out with no resolution and the code remained broken.
In the v2.6.30 x86 tree development cycle 32-bit subarch support
has been reworked and removed - and the Voyager code, beyond the
build problems already known, needs serious and significant
changes and probably a rewrite to support it.
CONFIG_X86_VOYAGER has been marked BROKEN then. The maintainer has
been notified but no patches have been sent so far to fix it.
While all other subarchs have been converted to the new scheme,
voyager is still broken. We'd prefer to receive patches which
clean up the current situation in a constructive way, but even in
case of removal there is no obstacle to add that support back
after the issues have been sorted out in a mutually acceptable
fashion.
So remove this inactive code for now.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix a memory leak identified by Rusty Russell during LCA09 by
kfree'ing the lg object instead of just clearing it when the
launcher closes.
Signed-off-by: Mark Wallis <mwallis@serialmonkey.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
We shouldn't be statically allocating the root device object,
so dynamically allocate it using root_device_register()
instead.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'cpus4096-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (66 commits)
x86: export vector_used_by_percpu_irq
x86: use logical apicid in x2apic_cluster's x2apic_cpu_mask_to_apicid_and()
sched: nominate preferred wakeup cpu, fix
x86: fix lguest used_vectors breakage, -v2
x86: fix warning in arch/x86/kernel/io_apic.c
sched: fix warning in kernel/sched.c
sched: move test_sd_parent() to an SMP section of sched.h
sched: add SD_BALANCE_NEWIDLE at MC and CPU level for sched_mc>0
sched: activate active load balancing in new idle cpus
sched: bias task wakeups to preferred semi-idle packages
sched: nominate preferred wakeup cpu
sched: favour lower logical cpu number for sched_mc balance
sched: framework for sched_mc/smt_power_savings=N
sched: convert BALANCE_FOR_xx_POWER to inline functions
x86: use possible_cpus=NUM to extend the possible cpus allowed
x86: fix cpu_mask_to_apicid_and to include cpu_online_mask
x86: update io_apic.c to the new cpumask code
x86: Introduce topology_core_cpumask()/topology_thread_cpumask()
x86: xen: use smp_call_function_many()
x86: use work_on_cpu in x86/kernel/cpu/mcheck/mce_amd_64.c
...
Fixed up trivial conflict in kernel/time/tick-sched.c manually
bus_id is gradually being removed, so use dev_name() instead.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This patch moves the initial guest page table creation code to the host,
so the launcher keeps working with PAE enabled configs.
Signed-off-by: Matias Zabaljauregui <zabaljauregui@gmail.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This allows each virtio user to hand in the alignment appropriate to
their virtio_ring structures.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
This doesn't really matter, since lguest is i386 only at the moment,
but we could actually choose a different value. (lguest doesn't have
a guarenteed ABI).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Impact: fix lguest, clean up
32-bit lguest used used_vectors to record vectors, but that model of
allocating vectors changed and got broken, after we changed vector
allocation to a per_cpu array.
Try enable that for 64bit, and the array is used for all vectors that
are not managed by vector_irq per_cpu array.
Also kill system_vectors[], that is now a duplication of the
used_vectors bitmap.
[ merged in cpus4096 due to io_apic.c cpumask changes. ]
[ -v2, fix build failure ]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Using a simple page table thrashing program I measure a slight
improvement. The program creates five processes. Each touches 1000
pages then schedules the next process. We repeat this 1000 times. As
lguest only caches 4 cr3 values, this rebuilds a lot of shadow page
tables requiring virt->phys mappings.
Before: 5.93 seconds
After: 5.40 seconds
(Counts of slow vs fastpath in this usage are 6092 and 2852462 respectively.)
And more importantly for lguest, the code is simpler.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
To support my little make-x86-bitops-use-proper-typechecking projectlet.
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
map_switcher allocates the array, unmap_switcher has to free it
accordingly.
Signed-off-by: Johannes Weiner <hannes@saeurebad.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Ron Minnich noticed that guest userspace gets a GPF when it tries to int3:
we need to copy the privilege level from the guest-supplied IDT to the real
IDT. int3 is the only common case where guest userspace expects to invoke
an interrupt, so that's the symptom of failing to do this.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
To prepare for virtio_ring transport feature bits, hook in a call in
all the users to manipulate them. This currently just clears all the
bits, since it doesn't understand any features.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Rather than explicitly handing the features to the lower-level, we just
hand the virtio_device and have it set the features. This make it clear
that it has the chance to manipulate the features of the device at this
point (and that all feature negotiation is already done).
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Anand Gadiyar