The do_ls() function has somewhat inconsistent handling of errors.
If reading the node's contents with xs_read() fails, then do_ls() will
just quietly not display the contents.
If reading the node's permissions with xs_get_permissions() fails, then
do_ls() will print a warning, continue, and ultimately won't exit with
an error code (unless another error happens).
If recursing into the node with xs_directory() fails, then do_ls() will
abort immediately, not printing any further nodes.
For persistent failure modes — such as ENOENT because a node has been
removed, or EACCES because it has had its permisions changed since the
xs_directory() on the parent directory returned its name — it's
obviously quite likely that if either of the first two errors occur for
a given node, then so will the third and thus xenstore-ls will abort.
The ENOENT one is actually a fairly common case, and has caused tools to
fail to clean up a network device because it *apparently* already
doesn't exist in xenstore.
There is a school of thought that says, "Well, xenstore-ls returned an
error. So the tools should not trust its output."
The natural corollary of this would surely be that the tools must re-run
xenstore-ls as many times as is necessary until its manages to exit
without hitting the race condition. I am not keen on that conclusion.
For the specific case of ENOENT it seems reasonable to declare that,
but for the timing, we might as well just not have seen that node at
all when calling xs_directory() for the parent. By ignoring the error,
we give acceptable output.
The issue can be reproduced as follows:
(dom0) # for a in `seq 1 1000` ; do
xenstore-write /local/domain/2/foo/$a $a ;
done
Now simultaneously:
(dom0) # for a in `seq 1 999` ; do
xenstore-rm /local/domain/2/foo/$a ;
done
(dom2) # while true ; do
./xenstore-ls -p /local/domain/2/foo | grep -c 1000 ;
done
We should expect to see node 1000 in the output, every time.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Ian Jackson <ian.jackson@eu.citrix.com>
The creation of dom0 can be relatively self-contained. Shift it into
a separate function and simplify __start_xen() a little bit.
This is a cleanup in its own right, but will be even more desireable
when live update provides an alternative path through __start_xen()
that doesn't involve creating a new dom0 at all.
Move the calculation of the 'initrd' parameter for create_dom0()
down past the cosmetic printk about NX support, because in the fullness
of time the whole initrd and create_dom0() part will be under the same
"not live update" conditional. And in the meantime it's just neater.
Also drop the explicit check for initrd to be module #0 since that would
be the dom0 kernel and the corresponding bit is always clear in
module_map.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Jan Beulich <jbeulich@suse.com>
This causes gcc (yes, and clang) to emit phony targets for each dependency.
This means that when a header file is deleted, the C files which *used*
to include it will no longer stop building with bogus out-of-date
dependencies like this:
make[5]: *** No rule to make target
'/home/dwmw2/git/xen/xen/include/asm/hvm/svm/amd-iommu-proto.h',
needed by 'p2m.o'. Stop.
Based on -MP post-dating -MP by many years it is assumed that the
behavior of -MP isn't the defualt just out of extreme caution. We're
sufficiently convinced that there are no undue side effects of this.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Set 'e' correctly to reflect the location that Xen is actually relocated
to from its default 2MiB location. Not 2MiB below that.
This is only vaguely a bug fix. The "missing" 2MiB would have been used
in the end, and fed to the allocator. It's just that other things don't
get to sit right up *next* to the Xen image, and it isn't very tidy.
For live update, I'd quite like a single contiguous region for the
reserved bootmem and Xen, allowing the 'slack' in the former to be used
when Xen itself grows larger. Let's not allow 2MiB of random heap pages
to get in the way...
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Just before smp_send_stop() re-enables interrupts when shutting down
for reboot or kexec, it calls __stop_this_cpu() which in turn calls
disable_local_APIC(), which puts the APIC back in to the mode Xen found
it in at boot.
If that means turning x2APIC off and going back into xAPIC mode, then
a timer interrupt occurring just after interrupts come back on will
lead to a GP# when apic_timer_interrupt() attempts to ack the IRQ
through the EOI register in x2APIC MSR 0x80b:
(XEN) Executing kexec image on cpu0
(XEN) ----[ Xen-4.14-unstable x86_64 debug=n Not tainted ]----
(XEN) CPU: 0
(XEN) RIP: e008:[<ffff82d08026c139>] apic_timer_interrupt+0x29/0x40
(XEN) RFLAGS: 0000000000010046 CONTEXT: hypervisor
(XEN) rax: 0000000000000000 rbx: 00000000000000fa rcx: 000000000000080b
...
(XEN) Xen code around <ffff82d08026c139> (apic_timer_interrupt+0x29/0x40):
(XEN) c0 b9 0b 08 00 00 89 c2 <0f> 30 31 ff e9 0e c9 fb ff 0f 1f 40 00 66 2e 0f
...
(XEN) Xen call trace:
(XEN) [<ffff82d08026c139>] R apic_timer_interrupt+0x29/0x40
(XEN) [<ffff82d080283825>] S do_IRQ+0x95/0x750
...
(XEN) [<ffff82d0802a0ad2>] S smp_send_stop+0x42/0xd0
We can't clear the global x2apic_enabled variable in disable_local_APIC()
itself because that runs on each CPU. Instead, correct it (by using
current_local_apic_mode()) in smp_send_stop() while interrupts are still
disabled immediately after calling __stop_this_cpu() for the boot CPU,
after all other CPUs have been stopped.
cf: d639bdd9bb ("x86/apic: Disable the LAPIC later in smp_send_stop()")
... which didn't quite fix it completely.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
We appear to have implemented a memcpy() in the low-memory trampoline
which we then call into from __start_xen(), for no adequately defined
reason.
Kill it with fire.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
The wakeup code is now relocated alongside the trampoline code, so
as long as we move idt_48 and gdt_48 up a little bit so that they're
visible in the real-mode segment that the wakeup code runs in, using
%ds is just fine here.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Tested-by: Andrew Cooper <andrew.cooper3@citrix.com>
The function is invoked with delta=0 before ExitBootServices() is called,
as a dummy run purely to validate that all the relocations can be handled.
This allows us to exit gracefully with an error message.
However, we have relocations in read-only sections such as .rodata and
.init.te(xt). Recent versions of UEFI will actually make those sections
read-only, which will cause a fault. This functionaity was added in
EDK2 commit d0e92aad4 ("MdeModulePkg/DxeCore: Add UEFI image protection.")
It's OK to actually make the changes in the later pass because UEFI will
tear down the protection when ExitBootServices() is called, because it
knows we're going to need to do this kind of thing.
Reported-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
This includes stuff like the hypercall tables which we really kind of want
to be read-only. And they were going into .data.read-mostly.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Julien Grall <julien.grall@arm.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
David Woodhouse