From a1f2ed2ad8b4ec28a5f1bc4fcb50ef57b69a28a2 Mon Sep 17 00:00:00 2001 From: Pavel Dovgalyuk Date: Fri, 11 May 2018 11:16:01 +0300 Subject: [PATCH] ps2: prevent changing irq state on save and load Commit 2858ab09e6f708e381fc1a1cc87e747a690c4884 changed PS/2 keyboard/mouse buffers to the standard size. However, its state may change when migrating from the old buffer size and therefore irq needs updating. But this change made wrong, because it throws the whole queue if there are too much data instead of cropping it. That commit also updates irq (because the queue state may change). But updating the irq may change the VM state (and determinism of the execution). E.g., when replaying the execution, one may save the VM state and the state of the interrupt controller will be updated at the moment of saving, instead of using the recorded update events. This patch makes the queue update deterministic: it removes the update_irq call and crops the queue to prevent losing the characters and changing the required irq status. Signed-off-by: Pavel Dovgalyuk Message-Id: <20180511081601.14610.39946.stgit@pasha-VirtualBox> Signed-off-by: Paolo Bonzini --- hw/input/ps2.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/hw/input/ps2.c b/hw/input/ps2.c index fdfcadf9a1..6c43fc2912 100644 --- a/hw/input/ps2.c +++ b/hw/input/ps2.c @@ -914,7 +914,12 @@ static void ps2_common_post_load(PS2State *s) uint8_t tmp_data[PS2_QUEUE_SIZE]; /* set the useful data buffer queue size, < PS2_QUEUE_SIZE */ - size = (q->count < 0 || q->count > PS2_QUEUE_SIZE) ? 0 : q->count; + size = q->count; + if (q->count < 0) { + size = 0; + } else if (q->count > PS2_QUEUE_SIZE) { + size = PS2_QUEUE_SIZE; + } /* move the queue elements to the start of data array */ for (i = 0; i < size; i++) { @@ -929,7 +934,6 @@ static void ps2_common_post_load(PS2State *s) q->rptr = 0; q->wptr = (size == PS2_QUEUE_SIZE) ? 0 : size; q->count = size; - s->update_irq(s->update_arg, q->count != 0); } static void ps2_kbd_reset(void *opaque)