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History log of /src/sys/dev/hyperv/vmbus.c
RevisionDateAuthorComments
 1.20  06-Sep-2025  riastradh hyperv(4): Use paravirt_membar_sync(9) where needed.

Annotate each remaining membar_sync with the bus_dmamap_sync that I
think it really ought to be. Sprinkle some more annotations of where
bus_dmamap_sync ought to go. (Although these likely don't matter --
except as __insn_barrier equivalents -- for hyperv on x86, and these
buffers are not likely to ever bounce, the syncs may be needed on Arm
for the underlying r-before-r/w and r/w-before-w ordering if nothing
else.)

PR kern/59618: occasional virtio block device lock ups/hangs

(hyperv(4) is not virtio(4) but the same fundamental issue arises.)
 1.19  29-Mar-2025  nonaka vmbus(4): Fix missing conversion to condvar(9).
 1.18  20-May-2022  nonaka branches: 1.18.4; 1.18.10;
Improve Hyper-V support.

vmbus(4):
- Added support for multichannel.

hvn(4):
- Added support for multichannel.
- Added support for change MTU.
- Added support for TX aggregation.
- Improve VLAN support.
- Improve checksum offload support.
 1.17  09-Apr-2022  riastradh sys: Use membar_release/acquire around reference drop.

This just goes through my recent reference count membar audit and
changes membar_exit to membar_release and membar_enter to
membar_acquire -- this should make everything cheaper on most CPUs
without hurting correctness, because membar_acquire is generally
cheaper than membar_enter.
 1.16  12-Mar-2022  riastradh sys: Membar audit around reference count releases.

If two threads are using an object that is freed when the reference
count goes to zero, we need to ensure that all memory operations
related to the object happen before freeing the object.

Using an atomic_dec_uint_nv(&refcnt) == 0 ensures that only one
thread takes responsibility for freeing, but it's not enough to
ensure that the other thread's memory operations happen before the
freeing.

Consider:

Thread A Thread B
obj->foo = 42; obj->baz = 73;
mumble(&obj->bar); grumble(&obj->quux);
/* membar_exit(); */ /* membar_exit(); */
atomic_dec -- not last atomic_dec -- last
/* membar_enter(); */
KASSERT(invariant(obj->foo,
obj->bar));
free_stuff(obj);

The memory barriers ensure that

obj->foo = 42;
mumble(&obj->bar);

in thread A happens before

KASSERT(invariant(obj->foo, obj->bar));
free_stuff(obj);

in thread B. Without them, this ordering is not guaranteed.

So in general it is necessary to do

membar_exit();
if (atomic_dec_uint_nv(&obj->refcnt) != 0)
return;
membar_enter();

to release a reference, for the `last one out hit the lights' style
of reference counting. (This is in contrast to the style where one
thread blocks new references and then waits under a lock for existing
ones to drain with a condvar -- no membar needed thanks to mutex(9).)

I searched for atomic_dec to find all these. Obviously we ought to
have a better abstraction for this because there's so much copypasta.
This is a stop-gap measure to fix actual bugs until we have that. It
would be nice if an abstraction could gracefully handle the different
styles of reference counting in use -- some years ago I drafted an
API for this, but making it cover everything got a little out of hand
(particularly with struct vnode::v_usecount) and I ended up setting
it aside to work on psref/localcount instead for better scalability.

I got bored of adding #ifdef __HAVE_ATOMIC_AS_MEMBAR everywhere, so I
only put it on things that look performance-critical on 5sec review.
We should really adopt membar_enter_preatomic/membar_exit_postatomic
or something (except they are applicable only to atomic r/m/w, not to
atomic_load/store_*, making the naming annoying) and get rid of all
the ifdefs.
 1.15  23-Dec-2021  yamaguchi hyper-v: move idt vector allocating to vmbus_init_interrupts_md()
for refactoring

And, the deallocating is also moved to
vmbus_deinit_interrupts_md().

reviewed by nonaka@n.o.
 1.14  07-Aug-2021  thorpej Merge thorpej-cfargs2.
 1.13  24-Apr-2021  thorpej branches: 1.13.8;
Merge thorpej-cfargs branch:

Simplify and make extensible the config_search() / config_found() /
config_attach() interfaces: rather than having different variants for
which arguments you want pass along, just have a single call that
takes a variadic list of tag-value arguments.

Adjust all call sites:
- Simplify wherever possible; don't pass along arguments that aren't
actually needed.
- Don't be explicit about what interface attribute is attaching if
the device only has one. (More simplification.)
- Add a config_probe() function to be used in indirect configuiration
situations, making is visibly easier to see when indirect config is
in play, and allowing for future change in semantics. (As of now,
this is just a wrapper around config_match(), but that is an
implementation detail.)

Remove unnecessary or redundant interface attributes where they're not
needed.

There are currently 5 "cfargs" defined:
- CFARG_SUBMATCH (submatch function for direct config)
- CFARG_SEARCH (search function for indirect config)
- CFARG_IATTR (interface attribte)
- CFARG_LOCATORS (locators array)
- CFARG_DEVHANDLE (devhandle_t - wraps OFW, ACPI, etc. handles)

...and a sentinel value CFARG_EOL.

Add some extra sanity checking to ensure that interface attributes
aren't ambiguous.

Use CFARG_DEVHANDLE in MI FDT, OFW, and ACPI code, and macppc and shark
ports to associate those device handles with device_t instance. This
will trickle trough to more places over time (need back-end for pre-OFW
Sun OBP; any others?).
 1.12  29-Jan-2021  nonaka branches: 1.12.2;
vmbus(4): Don't wait forever.
 1.11  26-May-2020  nonaka branches: 1.11.2;
vmbus(4): Do not call hyperv_dma_alloc() in interrupt context.

The channel offer and rescind process is performed on another context.
 1.10  26-May-2020  nonaka vmbus(4): Fixed incorrect use of vmbus_wait() in vmbus_channel_scan().

Found by kUBSan.
 1.9  25-May-2020  nonaka Use howmany() macro.
 1.8  10-Dec-2019  nonaka hvn(4) can be added and deleted dynamically.
 1.7  07-Dec-2019  nonaka Get a Hyper-V virtual processor id in cpu_hatch().

Currently, it is got in config_interrupts context.
However, since it is required when attaching a device,
it is got earlier than now.
 1.6  06-Dec-2019  nonaka Clear the allocated memory in hyperv_dma_alloc().
 1.5  22-Nov-2019  nonaka vmbus(4), hvn(4), hvkbd(4): Fixed wait time for tsleep(9).
 1.4  09-Jul-2019  nakayama branches: 1.4.2;
Zero clear the allocated ring buffer for vmbus_channel.
This change makes Hyper-V's vmbus devices work properly even after reboot.
 1.3  24-May-2019  nonaka branches: 1.3.2;
Added drivers for Hyper-V Synthetic Keyboard and Video device.
 1.2  15-Feb-2019  hannken branches: 1.2.2;
Add __diagused.
 1.1  15-Feb-2019  nonaka Added Microsoft Hyper-V support. It ported from OpenBSD and FreeBSD.

graphical console is not work on Gen.2 VM yet. To use the serial console,
enter "consdev com,0x3f8,115200" on efiboot.
 1.2.2.6  29-Jan-2021  martin Pull up following revision(s) (requested by nonaka in ticket #1647):

sys/dev/hyperv/if_hvn.c: revision 1.20 (via patch)
sys/dev/hyperv/hvkbd.c: revision 1.7 (via patch)
sys/dev/hyperv/vmbus.c: revision 1.12 (via patch)

hvkbd(4): Don't wait forever.
vmbus(4): Don't wait forever.
hvn(4): Don't wait forever.
 1.2.2.5  24-Nov-2019  martin Pull up following revision(s) (requested by nonaka in ticket #1455):

sys/dev/hyperv/if_hvn.c: revision 1.8
sys/dev/hyperv/if_hvn.c: revision 1.9
sys/dev/hyperv/hvkbd.c: revision 1.5
sys/dev/hyperv/hvkbd.c: revision 1.6
sys/dev/hyperv/vmbus.c: revision 1.5

vmbus(4), hvn(4), hvkbd(4): Fixed wait time for tsleep(9).
hvn(4), hvkbd(4): Only need to poll when cold.
 1.2.2.4  09-Jul-2019  martin Pull up following revision(s) (requested by nakayama in ticket #1286):

sys/dev/hyperv/vmbus.c: revision 1.4

Zero clear the allocated ring buffer for vmbus_channel.
This change makes Hyper-V's vmbus devices work properly even after reboot.
 1.2.2.3  12-Jun-2019  martin Pull up following revision(s) (requested by nonaka in ticket #1280):

sys/arch/x86/x86/consinit.c: revision 1.29
sys/dev/hyperv/vmbusvar.h: revision 1.2
sys/dev/hyperv/genfb_vmbusvar.h: revision 1.1
sys/arch/x86/x86/x86_autoconf.c: revision 1.78
sys/arch/x86/x86/identcpu.c: revision 1.91
sys/arch/x86/x86/hyperv.c: revision 1.2
sys/arch/x86/x86/hyperv.c: revision 1.3
sys/arch/x86/x86/hyperv.c: revision 1.4
sys/arch/i386/conf/GENERIC: revision 1.1207
sys/dev/wscons/wsconsio.h: revision 1.123
sys/arch/x86/x86/hypervvar.h: revision 1.1
sys/arch/amd64/conf/GENERIC: revision 1.528
sys/dev/hyperv/files.hyperv: revision 1.2
sys/arch/x86/include/autoconf.h: revision 1.6
sys/dev/hyperv/hyperv_common.c: revision 1.2
sys/arch/xen/x86/autoconf.c: revision 1.23
sys/arch/x86/pci/pci_machdep.c: revision 1.86
sys/dev/hyperv/hvkbd.c: revision 1.1
sys/dev/hyperv/hypervvar.h: revision 1.2
sys/dev/acpi/vmbus_acpi.c: revision 1.2
sys/dev/hyperv/vmbus.c: revision 1.3
sys/dev/hyperv/hvkbdvar.h: revision 1.1
sys/dev/hyperv/genfb_vmbus.c: revision 1.1

Added drivers for Hyper-V Synthetic Keyboard and Video device.

Avoid undefined reference to `hyperv_guid_video' without vmbus(4).

Avoid undefined reference to `hyperv_is_gen1' without hyperv(4).

Use efi_probe().
 1.2.2.2  09-Mar-2019  martin Pull up following revision(s) via patch (requested by nonaka in ticket #1210):

sys/dev/hyperv/vmbusvar.h: revision 1.1
sys/dev/hyperv/hvs.c: revision 1.1
sys/dev/hyperv/if_hvn.c: revision 1.1
sys/dev/hyperv/vmbusic.c: revision 1.1
sys/arch/x86/x86/lapic.c: revision 1.69
sys/arch/x86/isa/clock.c: revision 1.34
sys/arch/x86/include/intrdefs.h: revision 1.22
sys/arch/i386/conf/GENERIC: revision 1.1201
sys/arch/x86/x86/hyperv.c: revision 1.1
sys/arch/x86/include/cpu.h: revision 1.105
sys/arch/x86/x86/x86_machdep.c: revision 1.124
sys/arch/i386/conf/GENERIC: revision 1.1203
sys/arch/amd64/amd64/genassym.cf: revision 1.74
sys/arch/i386/conf/GENERIC: revision 1.1204
sys/arch/amd64/conf/GENERIC: revision 1.520
sys/arch/x86/x86/hypervreg.h: revision 1.1
sys/arch/amd64/amd64/vector.S: revision 1.69
sys/dev/hyperv/hvshutdown.c: revision 1.1
sys/dev/hyperv/hvshutdown.c: revision 1.2
sys/dev/usb/if_urndisreg.h: file removal
sys/arch/x86/x86/cpu.c: revision 1.167
sys/arch/x86/conf/files.x86: revision 1.107
sys/dev/usb/if_urndis.c: revision 1.20
sys/dev/hyperv/vmbusicreg.h: revision 1.1
sys/dev/hyperv/hvheartbeat.c: revision 1.1
sys/dev/hyperv/vmbusicreg.h: revision 1.2
sys/dev/hyperv/hvheartbeat.c: revision 1.2
sys/dev/hyperv/files.hyperv: revision 1.1
sys/dev/ic/rndisreg.h: revision 1.1
sys/arch/i386/i386/genassym.cf: revision 1.111
sys/dev/ic/rndisreg.h: revision 1.2
sys/dev/hyperv/hyperv_common.c: revision 1.1
sys/dev/hyperv/hvtimesync.c: revision 1.1
sys/dev/hyperv/hypervreg.h: revision 1.1
sys/dev/hyperv/hvtimesync.c: revision 1.2
sys/dev/hyperv/vmbusicvar.h: revision 1.1
sys/dev/hyperv/if_hvnreg.h: revision 1.1
sys/arch/x86/x86/lapic.c: revision 1.70
sys/arch/amd64/amd64/vector.S: revision 1.70
sys/dev/ic/ndisreg.h: revision 1.1
sys/arch/amd64/conf/GENERIC: revision 1.516
sys/dev/hyperv/hypervvar.h: revision 1.1
sys/arch/amd64/conf/GENERIC: revision 1.518
sys/arch/amd64/conf/GENERIC: revision 1.519
sys/arch/i386/conf/files.i386: revision 1.400
sys/dev/acpi/vmbus_acpi.c: revision 1.1
sys/dev/hyperv/vmbus.c: revision 1.1
sys/dev/hyperv/vmbus.c: revision 1.2
sys/arch/x86/x86/intr.c: revision 1.144
sys/arch/i386/i386/vector.S: revision 1.83
sys/arch/amd64/conf/files.amd64: revision 1.112

separate RNDIS definitions from urndis(4) for use with Hyper-V NetVSC.

-

Added Microsoft Hyper-V support. It ported from OpenBSD and FreeBSD.
graphical console is not work on Gen.2 VM yet. To use the serial console,
enter "consdev com,0x3f8,115200" on efiboot.

-

Add __diagused.

-

PR/53984: Partial revert of modify lapic_calibrate_timer() in lapic.c r1.69.

-

Update Hyper-V related drivers description.

-

Remove unused definition.

-

Rename the MODULE_*_HOOK() macros to MODULE_HOOK_*() as briefly
discussed on irc.
NFCI intended.

-

commented out hvkvp entry.

-

fix typo. pointed out by pgoyette@n.o.

-

Use IDTVEC instead of NENTRY for handle_hyperv_hypercall.

-

Rename the MODULE_*_HOOK() macros to MODULE_HOOK_*() as briefly
discussed on irc.
 1.2.2.1  15-Feb-2019  martin file vmbus.c was added on branch netbsd-8 on 2019-03-09 17:10:19 +0000
 1.3.2.3  08-Apr-2020  martin Merge changes from current as of 20200406
 1.3.2.2  10-Jun-2019  christos Sync with HEAD
 1.3.2.1  24-May-2019  christos file vmbus.c was added on branch phil-wifi on 2019-06-10 22:07:09 +0000
 1.4.2.2  04-Feb-2021  martin Pull up following revision(s) (requested by nonaka in ticket #1192):

sys/dev/hyperv/if_hvn.c: revision 1.20 (via patch)
sys/dev/hyperv/hvkbd.c: revision 1.7 (via patch)
sys/dev/hyperv/vmbus.c: revision 1.12 (via patch)

hvkbd(4): Don't wait forever.
vmbus(4): Don't wait forever.
hvn(4): Don't wait forever.
 1.4.2.1  24-Nov-2019  martin Pull up following revision(s) (requested by nonaka in ticket #464):

sys/dev/hyperv/if_hvn.c: revision 1.8
sys/dev/hyperv/if_hvn.c: revision 1.9
sys/dev/hyperv/hvkbd.c: revision 1.5
sys/dev/hyperv/hvkbd.c: revision 1.6
sys/dev/hyperv/vmbus.c: revision 1.5

vmbus(4), hvn(4), hvkbd(4): Fixed wait time for tsleep(9).
hvn(4), hvkbd(4): Only need to poll when cold.
 1.11.2.1  03-Apr-2021  thorpej Sync with HEAD.
 1.12.2.1  23-Mar-2021  thorpej Convert config_found_ia() call sites where the device only carries
a single interface attribute to bare config_found() calls.
 1.13.8.1  04-Aug-2021  thorpej Adapt to CFARGS().
 1.18.10.1  02-Aug-2025  perseant Sync with HEAD
 1.18.4.1  04-Apr-2025  martin Pull up following revision(s) (requested by nonaka in ticket #1079):

sys/dev/hyperv/vmbus.c: revision 1.19

vmbus(4): Fix missing conversion to condvar(9).

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