Re: [Qemu-devel] [PATCH v3 1/1] s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW
On 06/12/2018 01:55 PM, Cornelia Huck wrote:
> On Tue, 12 Jun 2018 12:04:48 +0200
> Christian Borntraeger wrote:
>
>> Right now the IPL device always starts from address 0x1 (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
>> ---
>> v2->v3:
>> - check for iplpsw to avoid assert on file errors
>> - use 4 bytes at 4 instead of 8 bytes at 0
>> v1->v2:
>> - use LINUX_MAGIC_ADDR define
>> - use assert for valid iplpsw pointer
>> - add endianess conversion
>> hw/s390x/ipl.c | 19 ++-
>> 1 file changed, 18 insertions(+), 1 deletion(-)
>>
>> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
>> index 04245b5258..1a42630962 100644
>> --- a/hw/s390x/ipl.c
>> +++ b/hw/s390x/ipl.c
>> @@ -29,6 +29,7 @@
>> #include "exec/exec-all.h"
>>
>> #define KERN_IMAGE_START0x01UL
>> +#define LINUX_MAGIC_ADDR0x010008UL
>> #define KERN_PARM_AREA 0x010480UL
>> #define INITRD_START0x80UL
>> #define INITRD_PARM_START 0x010408UL
>> @@ -105,7 +106,9 @@ 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;
>> +uint32_t *iplpsw;
>
> In case you respin: Can this be ipl_psw, please?
sure.
>
>> +uint64_t pentry;
>> +char *magic;
>> int kernel_size;
>> Error *err = NULL;
>>
>> @@ -157,6 +160,20 @@ 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(LINUX_MAGIC_ADDR);
>> +if (magic && !memcmp(magic, "S390EP", 6)) {
>> +pentry = KERN_IMAGE_START;
>> +} else {
>> +/* if not Linux use the IPL PSW */
>
> "use the address of the IPL PSW"?
Well we use the IPL PSW (and we need the address to get that) See the * before
iplpsw.
>
>> +iplpsw = rom_ptr(4);
>> +if (iplpsw) {
>> +pentry = be32_to_cpu(*iplpsw) & 0x7fffUL;
>> +} else {
>> +error_setg(&err, "Could not get IPL PSW");
>> +goto error;
>> +}
>> +}
>> }
>> if (kernel_size < 0) {
>> error_setg(&err, "could not load kernel '%s'", ipl->kernel);
>
> Is this ever reached now? In any case, it might make sense to move this
Hmm, Right. If kernel_size < 0 then magic and ipl_psw should be NULL and we
error out early
> up, as the "could not load kernel 'plahh'" message seems more useful
> than "Could not get IPL PSW"...
>
> Also, further below we copy ipl->cmdline if we think we're dealing with
> a Linux image. Would it make sense to explicitly check for the Linux
> magic there as well? (Separate patch, of course.)
>
> Can/should netboot do a similar check? It uses KERN_IMAGE_START
> unconditionally if it wasn't an ELF file.
I think we already changed that there (I asked for that change).
Re: [Qemu-devel] [PATCH v3 1/1] s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW
On Tue, 12 Jun 2018 12:04:48 +0200
Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x1 (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
> ---
> v2->v3:
> - check for iplpsw to avoid assert on file errors
> - use 4 bytes at 4 instead of 8 bytes at 0
> v1->v2:
> - use LINUX_MAGIC_ADDR define
> - use assert for valid iplpsw pointer
> - add endianess conversion
> hw/s390x/ipl.c | 19 ++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 04245b5258..1a42630962 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -29,6 +29,7 @@
> #include "exec/exec-all.h"
>
> #define KERN_IMAGE_START0x01UL
> +#define LINUX_MAGIC_ADDR0x010008UL
> #define KERN_PARM_AREA 0x010480UL
> #define INITRD_START0x80UL
> #define INITRD_PARM_START 0x010408UL
> @@ -105,7 +106,9 @@ 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;
> +uint32_t *iplpsw;
In case you respin: Can this be ipl_psw, please?
> +uint64_t pentry;
> +char *magic;
> int kernel_size;
> Error *err = NULL;
>
> @@ -157,6 +160,20 @@ 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(LINUX_MAGIC_ADDR);
> +if (magic && !memcmp(magic, "S390EP", 6)) {
> +pentry = KERN_IMAGE_START;
> +} else {
> +/* if not Linux use the IPL PSW */
"use the address of the IPL PSW"?
> +iplpsw = rom_ptr(4);
> +if (iplpsw) {
> +pentry = be32_to_cpu(*iplpsw) & 0x7fffUL;
> +} else {
> +error_setg(&err, "Could not get IPL PSW");
> +goto error;
> +}
> +}
> }
> if (kernel_size < 0) {
> error_setg(&err, "could not load kernel '%s'", ipl->kernel);
Is this ever reached now? In any case, it might make sense to move this
up, as the "could not load kernel 'plahh'" message seems more useful
than "Could not get IPL PSW"...
Also, further below we copy ipl->cmdline if we think we're dealing with
a Linux image. Would it make sense to explicitly check for the Linux
magic there as well? (Separate patch, of course.)
Can/should netboot do a similar check? It uses KERN_IMAGE_START
unconditionally if it wasn't an ELF file.
Re: [Qemu-devel] [PATCH v3 1/1] s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW
On 12.06.2018 12:04, Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x1 (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
> ---
> v2->v3:
> - check for iplpsw to avoid assert on file errors
> - use 4 bytes at 4 instead of 8 bytes at 0
> v1->v2:
> - use LINUX_MAGIC_ADDR define
> - use assert for valid iplpsw pointer
> - add endianess conversion
> hw/s390x/ipl.c | 19 ++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 04245b5258..1a42630962 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -29,6 +29,7 @@
> #include "exec/exec-all.h"
>
> #define KERN_IMAGE_START0x01UL
> +#define LINUX_MAGIC_ADDR0x010008UL
> #define KERN_PARM_AREA 0x010480UL
> #define INITRD_START0x80UL
> #define INITRD_PARM_START 0x010408UL
> @@ -105,7 +106,9 @@ 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;
> +uint32_t *iplpsw;
> +uint64_t pentry;
> +char *magic;
> int kernel_size;
> Error *err = NULL;
>
> @@ -157,6 +160,20 @@ 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(LINUX_MAGIC_ADDR);
> +if (magic && !memcmp(magic, "S390EP", 6)) {
> +pentry = KERN_IMAGE_START;
> +} else {
> +/* if not Linux use the IPL PSW */
> +iplpsw = rom_ptr(4);
> +if (iplpsw) {
> +pentry = be32_to_cpu(*iplpsw) & 0x7fffUL;
> +} else {
> +error_setg(&err, "Could not get IPL PSW");
> +goto error;
> +}
> +}
> }
> if (kernel_size < 0) {
> error_setg(&err, "could not load kernel '%s'", ipl->kernel);
>
Reviewed-by: Thomas Huth
Re: [Qemu-devel] [PATCH v3 1/1] s390x/ipl: Try to detect Linux vs non Linux for initial IPL PSW
On 12.06.2018 12:04, Christian Borntraeger wrote:
> Right now the IPL device always starts from address 0x1 (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
> ---
> v2->v3:
> - check for iplpsw to avoid assert on file errors
> - use 4 bytes at 4 instead of 8 bytes at 0
I trust you that this is the right thing to do :)
Reviewed-by: David Hildenbrand
> v1->v2:
> - use LINUX_MAGIC_ADDR define
> - use assert for valid iplpsw pointer
> - add endianess conversion
> hw/s390x/ipl.c | 19 ++-
> 1 file changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 04245b5258..1a42630962 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -29,6 +29,7 @@
> #include "exec/exec-all.h"
>
> #define KERN_IMAGE_START0x01UL
> +#define LINUX_MAGIC_ADDR0x010008UL
> #define KERN_PARM_AREA 0x010480UL
> #define INITRD_START0x80UL
> #define INITRD_PARM_START 0x010408UL
> @@ -105,7 +106,9 @@ 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;
> +uint32_t *iplpsw;
> +uint64_t pentry;
> +char *magic;
> int kernel_size;
> Error *err = NULL;
>
> @@ -157,6 +160,20 @@ 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(LINUX_MAGIC_ADDR);
> +if (magic && !memcmp(magic, "S390EP", 6)) {
> +pentry = KERN_IMAGE_START;
> +} else {
> +/* if not Linux use the IPL PSW */
> +iplpsw = rom_ptr(4);
> +if (iplpsw) {
> +pentry = be32_to_cpu(*iplpsw) & 0x7fffUL;
> +} else {
> +error_setg(&err, "Could not get IPL PSW");
> +goto error;
> +}
> +}
> }
> if (kernel_size < 0) {
> error_setg(&err, "could not load kernel '%s'", ipl->kernel);
>
--
Thanks,
David / dhildenb
