[PATCH v2 10/11] pckbd: correctly disable PS/2 communication

From: "Volker Rümelin" <vr_qemu@t-online.de>
To: "Michael S. Tsirkin" <mst@redhat.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Philippe Mathieu-Daudé" <philmd@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: [PATCH v2 10/11] pckbd: correctly disable PS/2 communication
Date: Fri,  7 May 2021 20:09:52 +0200	[thread overview]
Message-ID: <20210507180953.8530-10-vr_qemu@t-online.de> (raw)
In-Reply-To: <a898b0d5-7086-9699-ae8b-9524ad319b01@t-online.de>

Currently the PS/2 controller command KBD_CCMD_MOUSE_DISABLE
doesn't disable the PS/2 mouse communication at all, and the
PS/2 controller commands KBD_CCMD_KBD_DISABLE and
KBD_CCMD_KBD_ENABLE disable and enable the keyboard interrupt,
which is very different from what a real PS/2 controller does.
A guest may notice the difference.

Mask out pending data on disabled queues to correctly disable
the PS/2 controller communication.

Signed-off-by: Volker Rümelin <vr_qemu@t-online.de>
---
 hw/input/pckbd.c | 29 ++++++++++++++++++++++-------
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/hw/input/pckbd.c b/hw/input/pckbd.c
index 3ecc9c74ab..7c476f7a3e 100644
--- a/hw/input/pckbd.c
+++ b/hw/input/pckbd.c
@@ -130,10 +130,12 @@
 #define MOUSE_STATUS_ENABLED    0x20
 #define MOUSE_STATUS_SCALE21    0x10
 
-#define KBD_PENDING_KBD         1
-#define KBD_PENDING_AUX         2
+#define KBD_PENDING_KBD_V3      0x01
+#define KBD_PENDING_AUX_V3      0x02
 #define KBD_PENDING_CTRL_KBD    0x04
 #define KBD_PENDING_CTRL_AUX    0x08
+#define KBD_PENDING_KBD         KBD_MODE_DISABLE_KBD    /* 0x10 */
+#define KBD_PENDING_AUX         KBD_MODE_DISABLE_MOUSE  /* 0x20 */
 
 #define KBD_MIGR_TIMER_PENDING  0x1
 
@@ -163,8 +165,6 @@ typedef struct KBDState {
     hwaddr mask;
 } KBDState;
 
-/* XXX: not generating the irqs if KBD_MODE_DISABLE_KBD is set may be
-   incorrect, but it avoids having to simulate exact delays */
 static void kbd_update_irq_lines(KBDState *s)
 {
     int irq_kbd_level, irq_mouse_level;
@@ -178,8 +178,7 @@ static void kbd_update_irq_lines(KBDState *s)
                 irq_mouse_level = 1;
             }
         } else {
-            if ((s->mode & KBD_MODE_KBD_INT) &&
-                !(s->mode & KBD_MODE_DISABLE_KBD)) {
+            if (s->mode & KBD_MODE_KBD_INT) {
                 irq_kbd_level = 1;
             }
         }
@@ -197,7 +196,7 @@ static void kbd_deassert_irq(KBDState *s)
 
 static uint8_t kbd_pending(KBDState *s)
 {
-    return s->pending;
+    return s->pending & (~s->mode | ~(KBD_PENDING_KBD | KBD_PENDING_AUX));
 }
 
 /* update irq and KBD_STAT_[MOUSE_]OBF */
@@ -357,6 +356,7 @@ static void kbd_write_command(void *opaque, hwaddr addr,
         break;
     case KBD_CCMD_MOUSE_ENABLE:
         s->mode &= ~KBD_MODE_DISABLE_MOUSE;
+        kbd_safe_update_irq(s);
         break;
     case KBD_CCMD_TEST_MOUSE:
         kbd_queue(s, 0x00, 0);
@@ -436,6 +436,9 @@ static void kbd_write_data(void *opaque, hwaddr addr,
     switch(s->write_cmd) {
     case 0:
         ps2_write_keyboard(s->kbd, val);
+        /* sending data to the keyboard reenables PS/2 communication */
+        s->mode &= ~KBD_MODE_DISABLE_KBD;
+        kbd_safe_update_irq(s);
         break;
     case KBD_CCMD_WRITE_MODE:
         s->mode = val;
@@ -462,6 +465,9 @@ static void kbd_write_data(void *opaque, hwaddr addr,
         break;
     case KBD_CCMD_WRITE_MOUSE:
         ps2_write_mouse(s->mouse, val);
+        /* sending data to the mouse reenables PS/2 communication */
+        s->mode &= ~KBD_MODE_DISABLE_MOUSE;
+        kbd_safe_update_irq(s);
         break;
     default:
         break;
@@ -539,7 +545,16 @@ static int kbd_post_load(void *opaque, int version_id)
         s->obsrc = s->status & KBD_STAT_OBF ?
             (s->status & KBD_STAT_MOUSE_OBF ? KBD_OBSRC_MOUSE : KBD_OBSRC_KBD) :
             0;
+        if (s->pending & KBD_PENDING_KBD_V3) {
+            s->pending |= KBD_PENDING_KBD;
+        }
+        if (s->pending & KBD_PENDING_AUX_V3) {
+            s->pending |= KBD_PENDING_AUX;
+        }
     }
+    /* clear all unused flags */
+    s->pending &= KBD_PENDING_CTRL_KBD | KBD_PENDING_CTRL_AUX |
+                  KBD_PENDING_KBD | KBD_PENDING_AUX;
     if (s->migration_flags & KBD_MIGR_TIMER_PENDING) {
         kbd_throttle_timeout(s);
     }
-- 
2.26.2


