diff mbox series

s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW

Message ID 20180508141506.56480-1-borntraeger@de.ibm.com
State New
Headers show
Series s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW | expand

Commit Message

Christian Borntraeger May 8, 2018, 2:15 p.m. UTC 
Right now the IPL device always starts from address 0x10000 (the usual
Linux entry point). To run other guests (e.g. test programs) it is
useful to use the IPL PSW from address 0. We can use the Linux magic
at 0x10008 to decide.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Jason J. Herne <jjherne@linux.ibm.com>
---
 hw/s390x/ipl.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

Comments

Thomas Huth May 8, 2018, 2:24 p.m. UTC | #1 
On 08.05.2018 16:15, Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x10000 (the usual
> Linux entry point). To run other guests (e.g. test programs) it is
> useful to use the IPL PSW from address 0. We can use the Linux magic
> at 0x10008 to decide.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Acked-by: Jason J. Herne <jjherne@linux.ibm.com>
> ---
>  hw/s390x/ipl.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 150f6c0582..c0fed26f03 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -104,7 +104,9 @@ static uint64_t bios_translate_addr(void *opaque, uint64_t srcaddr)
>  static void s390_ipl_realize(DeviceState *dev, Error **errp)
>  {
>      S390IPLState *ipl = S390_IPL(dev);
> -    uint64_t pentry = KERN_IMAGE_START;
> +    uint64_t *iplpsw;
> +    uint64_t pentry;
> +    char *magic;
>      int kernel_size;
>      Error *err = NULL;
>  
> @@ -156,6 +158,17 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
>                                 NULL, 1, EM_S390, 0, 0);
>          if (kernel_size < 0) {
>              kernel_size = load_image_targphys(ipl->kernel, 0, ram_size);
> +            /* if this is Linux use KERN_IMAGE_START */
> +            magic = rom_ptr(0x10008);
> +            if (magic && !memcmp(magic, "S390EP", 6)) {
> +                pentry = KERN_IMAGE_START;
> +            } else {
> +                /* if not Linux use the IPL PSW */
> +                iplpsw = rom_ptr(0);
> +                if (iplpsw) {
> +                    pentry = *iplpsw & 0x7fffffffUL;
> +                }

else {
    error_report("Failed to determine entry point");
    exit(1);
}

?

Otherwise some version of GCC might complain that pentry is used
uninitialized later.

Alternatively, use "assert(iplpsw)" instead of the "if (iplpws)" ?

> +            }
>          }
>          if (kernel_size < 0) {
>              error_setg(&err, "could not load kernel '%s'", ipl->kernel);
> 

 Thomas
Christian Borntraeger May 8, 2018, 4:46 p.m. UTC | #2 
On 05/08/2018 04:15 PM, Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x10000 (the usual
> Linux entry point). To run other guests (e.g. test programs) it is
> useful to use the IPL PSW from address 0. We can use the Linux magic
> at 0x10008 to decide.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Acked-by: Jason J. Herne <jjherne@linux.ibm.com>
> ---
>  hw/s390x/ipl.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 150f6c0582..c0fed26f03 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -104,7 +104,9 @@ static uint64_t bios_translate_addr(void *opaque, uint64_t srcaddr)
>  static void s390_ipl_realize(DeviceState *dev, Error **errp)
>  {
>      S390IPLState *ipl = S390_IPL(dev);
> -    uint64_t pentry = KERN_IMAGE_START;
> +    uint64_t *iplpsw;
> +    uint64_t pentry;
> +    char *magic;
>      int kernel_size;
>      Error *err = NULL;
>  
> @@ -156,6 +158,17 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
>                                 NULL, 1, EM_S390, 0, 0);
>          if (kernel_size < 0) {
>              kernel_size = load_image_targphys(ipl->kernel, 0, ram_size);
> +            /* if this is Linux use KERN_IMAGE_START */
> +            magic = rom_ptr(0x10008);
> +            if (magic && !memcmp(magic, "S390EP", 6)) {
> +                pentry = KERN_IMAGE_START;
> +            } else {
> +                /* if not Linux use the IPL PSW */
> +                iplpsw = rom_ptr(0);
> +                if (iplpsw) {
> +                    pentry = *iplpsw & 0x7fffffffUL;

This needs an endianess conversion I think.
Christian Borntraeger May 8, 2018, 4:47 p.m. UTC | #3 
On 05/08/2018 04:15 PM, Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x10000 (the usual
> Linux entry point). To run other guests (e.g. test programs) it is
> useful to use the IPL PSW from address 0. We can use the Linux magic
> at 0x10008 to decide.
> 
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Acked-by: Jason J. Herne <jjherne@linux.ibm.com>
> ---
>  hw/s390x/ipl.c | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 150f6c0582..c0fed26f03 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -104,7 +104,9 @@ static uint64_t bios_translate_addr(void *opaque, uint64_t srcaddr)
>  static void s390_ipl_realize(DeviceState *dev, Error **errp)
>  {
>      S390IPLState *ipl = S390_IPL(dev);
> -    uint64_t pentry = KERN_IMAGE_START;
> +    uint64_t *iplpsw;
> +    uint64_t pentry;
> +    char *magic;
>      int kernel_size;
>      Error *err = NULL;
>  
> @@ -156,6 +158,17 @@ static void s390_ipl_realize(DeviceState *dev, Error **errp)
>                                 NULL, 1, EM_S390, 0, 0);
>          if (kernel_size < 0) {
>              kernel_size = load_image_targphys(ipl->kernel, 0, ram_size);
> +            /* if this is Linux use KERN_IMAGE_START */
> +            magic = rom_ptr(0x10008);
> +            if (magic && !memcmp(magic, "S390EP", 6)) {
> +                pentry = KERN_IMAGE_START;
> +            } else {
> +                /* if not Linux use the IPL PSW */
> +                iplpsw = rom_ptr(0);
> +                if (iplpsw) {
> +                    pentry = *iplpsw & 0x7fffffffUL;

I forgot endianess conversion here.


> +                }
> +            }
>          }
>          if (kernel_size < 0) {
>              error_setg(&err, "could not load kernel '%s'", ipl->kernel);
>
diff mbox series

Patch

diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
index 150f6c0582..c0fed26f03 100644
--- a/hw/s390x/ipl.c
+++ b/hw/s390x/ipl.c
@@ -104,7 +104,9 @@  static uint64_t bios_translate_addr(void *opaque, uint64_t srcaddr)
 static void s390_ipl_realize(DeviceState *dev, Error **errp)
 {
     S390IPLState *ipl = S390_IPL(dev);
-    uint64_t pentry = KERN_IMAGE_START;
+    uint64_t *iplpsw;
+    uint64_t pentry;
+    char *magic;
     int kernel_size;
     Error *err = NULL;
 
@@ -156,6 +158,17 @@  static void s390_ipl_realize(DeviceState *dev, Error **errp)
                                NULL, 1, EM_S390, 0, 0);
         if (kernel_size < 0) {
             kernel_size = load_image_targphys(ipl->kernel, 0, ram_size);
+            /* if this is Linux use KERN_IMAGE_START */
+            magic = rom_ptr(0x10008);
+            if (magic && !memcmp(magic, "S390EP", 6)) {
+                pentry = KERN_IMAGE_START;
+            } else {
+                /* if not Linux use the IPL PSW */
+                iplpsw = rom_ptr(0);
+                if (iplpsw) {
+                    pentry = *iplpsw & 0x7fffffffUL;
+                }
+            }
         }
         if (kernel_size < 0) {
             error_setg(&err, "could not load kernel '%s'", ipl->kernel);