s390-ccw: set cp_receive mask only when needed and consume pending service irqs

It is possible while waiting for multiple types of external
interrupts that we might have pending irqs remaining between
irq consumption and irq-type disabling. Those interrupts
could potentially propagate to the guest after IPL completes
and cause unwanted behavior.

As it is today, the SCLP will only recognize write events that
are enabled by the control program's send and receive masks. To
limit the window for, and prevent further irqs from, ASCII
console events (specifically keystrokes), we should only enable
the control program's receive mask when we need it.

While we're at it, remove assignment of the (non control program)
send and receive masks, as those are actually set by the SCLP.

Signed-off-by: Collin L. Walling <[email protected]>
Reviewed-by: Thomas Huth <[email protected]>
Acked-by: Christian Borntraeger <[email protected]>
Signed-off-by: Thomas Huth <[email protected]>

diff --git a/pc-bios/s390-ccw/menu.c b/pc-bios/s390-ccw/menu.c
index b99ff03298839299815fcad8717fb5f0940e2f10..8d55869448e49a6b15ff78400732b383f07ebf92 100644 (file)
--- a/pc-bios/s390-ccw/menu.c
+++ b/pc-bios/s390-ccw/menu.c
@@ -11,6 +11,7 @@
 
 #include "libc.h"
 #include "s390-ccw.h"
+#include "sclp.h"
 
 #define KEYCODE_NO_INP '\0'
 #define KEYCODE_ESCAPE '\033'
@@ -116,8 +117,12 @@ static int get_index(void)
 
     memset(buf, 0, sizeof(buf));
 
+    sclp_set_write_mask(SCLP_EVENT_MASK_MSG_ASCII, SCLP_EVENT_MASK_MSG_ASCII);
+
     len = read_prompt(buf, sizeof(buf) - 1);
 
+    sclp_set_write_mask(0, SCLP_EVENT_MASK_MSG_ASCII);
+
     /* If no input, boot default */
     if (len == 0) {
         return 0;

diff --git a/pc-bios/s390-ccw/s390-ccw.h b/pc-bios/s390-ccw/s390-ccw.h
index aeba8b0a991653ef922ea436625fb651d69cef45..c4ddf9f228dc6f7bbbc97682cfc74df481e90ec3 100644 (file)
--- a/pc-bios/s390-ccw/s390-ccw.h
+++ b/pc-bios/s390-ccw/s390-ccw.h
@@ -69,6 +69,7 @@ unsigned int get_loadparm_index(void);
 
 /* sclp.c */
 void sclp_print(const char *string);
+void sclp_set_write_mask(uint32_t receive_mask, uint32_t send_mask);
 void sclp_setup(void);
 void sclp_get_loadparm_ascii(char *loadparm);
 int sclp_read(char *str, size_t count);

diff --git a/pc-bios/s390-ccw/sclp.c b/pc-bios/s390-ccw/sclp.c
index a2f25ebd4fc2e9ab03fb2efabea53717ef15d5ef..3836cb4716bdb69da719d8db8ed0921df9d465f1 100644 (file)
--- a/pc-bios/s390-ccw/sclp.c
+++ b/pc-bios/s390-ccw/sclp.c
@@ -46,23 +46,21 @@ static int sclp_service_call(unsigned int command, void *sccb)
         return 0;
 }
 
-static void sclp_set_write_mask(void)
+void sclp_set_write_mask(uint32_t receive_mask, uint32_t send_mask)
 {
     WriteEventMask *sccb = (void *)_sccb;
 
     sccb->h.length = sizeof(WriteEventMask);
     sccb->mask_length = sizeof(unsigned int);
-    sccb->receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->cp_receive_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->send_mask = SCLP_EVENT_MASK_MSG_ASCII;
-    sccb->cp_send_mask = SCLP_EVENT_MASK_MSG_ASCII;
+    sccb->cp_receive_mask = receive_mask;
+    sccb->cp_send_mask = send_mask;
 
     sclp_service_call(SCLP_CMD_WRITE_EVENT_MASK, sccb);
 }
 
 void sclp_setup(void)
 {
-    sclp_set_write_mask();
+    sclp_set_write_mask(0, SCLP_EVENT_MASK_MSG_ASCII);
 }
 
 long write(int fd, const void *str, size_t len)