[Qemu-devel] [PATCH] Ignore IDE command if issued while IDE is busy.

[Gleb Natapov]

Feature, Sector Count, LBA Low/Mid/High and Device registers should be
written only when both BSY and DRQ are cleared to zero.
Command register shall only be written when BSY and DRQ are set to zero
for all commands except DEVICE RESET.
Data Port register shall be accessed for host PIO data transfer only when
DRQ is set to one.

Signed-off-by: Gleb Natapov <address@hidden>
---

 hw/ide.c |   26 ++++++++++++++++++++++++++
 1 files changed, 26 insertions(+), 0 deletions(-)

diff --git a/hw/ide.c b/hw/ide.c
index 6b14e8f..45591cc 100644
--- a/hw/ide.c
+++ b/hw/ide.c
@@ -1981,6 +1981,11 @@ static void ide_ioport_write(void *opaque, uint32_t 
addr, uint32_t val)
 #endif
 
     addr &= 7;
+
+    /* ignore writes to command block while busy with previous command */
+    if (addr != 7 && (ide_if->cur_drive->status & (BUSY_STAT|DRQ_STAT)))
+        return;
+
     switch(addr) {
     case 0:
         break;
@@ -2040,6 +2045,10 @@ static void ide_ioport_write(void *opaque, uint32_t 
addr, uint32_t val)
         if (s != ide_if && !s->bs)
             break;
 
+        /* Only DEVICE RESET is allowed while BSY or/and DRQ are set */
+        if ((s->status & (BUSY_STAT|DRQ_STAT)) && val != WIN_DEVICE_RESET)
+            break;
+
         switch(val) {
         case WIN_IDENTIFY:
             if (s->bs && !s->is_cdrom) {
@@ -2498,6 +2507,10 @@ static void ide_data_writew(void *opaque, uint32_t addr, 
uint32_t val)
     IDEState *s = ((IDEState *)opaque)->cur_drive;
     uint8_t *p;
 
+    /* PIO data access allowed only when DRQ bit is set */
+    if (!(s->status & DRQ_STAT))
+        return;
+
     p = s->data_ptr;
     *(uint16_t *)p = le16_to_cpu(val);
     p += 2;
@@ -2511,6 +2524,11 @@ static uint32_t ide_data_readw(void *opaque, uint32_t 
addr)
     IDEState *s = ((IDEState *)opaque)->cur_drive;
     uint8_t *p;
     int ret;
+
+    /* PIO data access allowed only when DRQ bit is set */
+    if (!(s->status & DRQ_STAT))
+        return;
+
     p = s->data_ptr;
     ret = cpu_to_le16(*(uint16_t *)p);
     p += 2;
@@ -2525,6 +2543,10 @@ static void ide_data_writel(void *opaque, uint32_t addr, 
uint32_t val)
     IDEState *s = ((IDEState *)opaque)->cur_drive;
     uint8_t *p;
 
+    /* PIO data access allowed only when DRQ bit is set */
+    if (!(s->status & DRQ_STAT))
+        return;
+
     p = s->data_ptr;
     *(uint32_t *)p = le32_to_cpu(val);
     p += 4;
@@ -2539,6 +2561,10 @@ static uint32_t ide_data_readl(void *opaque, uint32_t 
addr)
     uint8_t *p;
     int ret;
 
+    /* PIO data access allowed only when DRQ bit is set */
+    if (!(s->status & DRQ_STAT))
+        return;
+
     p = s->data_ptr;
     ret = cpu_to_le32(*(uint32_t *)p);
     p += 4;