From 9596ef7c7b8528bedb240792ea1fb598543ad3c4 Mon Sep 17 00:00:00 2001 From: "Denis V. Lunev" Date: Fri, 27 Nov 2015 09:48:41 +0300 Subject: e1000: fix hang of win2k12 shutdown with flood ping e1000 driver in Win2k12 is really well rotten. It 100% hangs on shutdown of UP VM under flood ping. The guest checks card state and reinjects itself interrupt in a loop. This is fatal for UP machine. There is no good way to fix this misbehavior but to kludge it. The emulation has interrupt throttling register aka ITR which limits interrupt rate and allows the guest to proceed this phase. There is no problem with this kludge for Linux guests - it adjust the value of it itself. On the other hand according to the initial research in commit e9845f0985f088dd01790f4821026df0afba5795 Author: Vincenzo Maffione Date: Fri Aug 2 18:30:52 2013 +0200 e1000: add interrupt mitigation support ... Interrupt mitigation boosts performance when the guest suffers from an high interrupt rate (i.e. receiving short UDP packets at high packet rate). For some numerical results see the following link http://info.iet.unipi.it/~luigi/papers/20130520-rizzo-vm.pdf this should also boost performance a bit. See https://bugzilla.redhat.com/show_bug.cgi?id=874406 for additional details. Signed-off-by: Denis V. Lunev CC: Vincenzo Maffione CC: Stefan Hajnoczi Signed-off-by: Jason Wang --- hw/net/e1000.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'hw') diff --git a/hw/net/e1000.c b/hw/net/e1000.c index 910de3a7be..153124485d 100644 --- a/hw/net/e1000.c +++ b/hw/net/e1000.c @@ -426,6 +426,11 @@ static void e1000_reset(void *opaque) e1000_link_down(d); } + /* Throttle interrupts to prevent guest (e.g Win 2012) from + * reinjecting interrupts endlessly. TODO: fix non ITR case. + */ + d->mac_reg[ITR] = 250; + /* Some guests expect pre-initialized RAH/RAL (AddrValid flag + MACaddr) */ d->mac_reg[RA] = 0; d->mac_reg[RA + 1] = E1000_RAH_AV; -- cgit v1.2.3