Re: [Qemu-devel] [PATCH 3/5] s390x/ipl: Load network boot image

[Farhan Ali]

Hi Thomas,

Thanks for the review.

On 02/20/2017 10:28 AM, Thomas Huth wrote:
> On 20.02.2017 15:19, Cornelia Huck wrote:
> > From: Farhan Ali <address@hidden>
> >
> > Load the network boot image into guest RAM when the boot
> > device selected is a network device. Use some of the reserved
> > space in IplBlockCcw to store the start address of the netboot
> > image.
> >
> > A user could also use 'chreipl'(diag 308/5) to change the boot device.
> > So every time we update the IPLB, we need to verify if the selected
> > boot device is a network device so we can appropriately load the
> > network boot image.
> >
> > Signed-off-by: Farhan Ali <address@hidden>
> > Signed-off-by: Cornelia Huck <address@hidden>
> > ---
> >  hw/s390x/ipl.c | 86 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> >  hw/s390x/ipl.h |  4 ++-
> >  2 files changed, 89 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> > index fd656718a7..80e05cc7a5 100644
> > --- a/hw/s390x/ipl.c
> > +++ b/hw/s390x/ipl.c
> > @@ -20,6 +20,7 @@
> >  #include "hw/s390x/virtio-ccw.h"
> >  #include "hw/s390x/css.h"
> >  #include "ipl.h"
> > +#include "qemu/error-report.h"
> >
> >  #define KERN_IMAGE_START                0x010000UL
> >  #define KERN_PARM_AREA                  0x010480UL
> > @@ -227,6 +228,12 @@ static bool s390_gen_initial_iplb(S390IPLState *ipl)
> >                  TYPE_VIRTIO_CCW_DEVICE);
> >          SCSIDevice *sd = (SCSIDevice *) object_dynamic_cast(OBJECT(dev_st),
> >                                                              TYPE_SCSI_DEVICE);
> > +        VirtIONet *vn = (VirtIONet *) object_dynamic_cast(OBJECT(dev_st),
> > +                                                          TYPE_VIRTIO_NET);
> > +
> > +        if (vn) {
> > +            ipl->netboot = true;
> > +        }
> >          if (virtio_ccw_dev) {
> >              CcwDevice *ccw_dev = CCW_DEVICE(virtio_ccw_dev);
> >
> > @@ -259,12 +266,84 @@ static bool s390_gen_initial_iplb(S390IPLState *ipl)
> >      return false;
> >  }
> >
> > +static int load_netboot_image(void)
> > +{
> > +
>
> Please remove that empty line above.

Will do.

> > +    S390IPLState *ipl = get_ipl_device();
> > +    char *netboot_filename;
> > +    MemoryRegion *sysmem =  get_system_memory();
> > +    MemoryRegion *mr = NULL;
> > +    void *ram_ptr = NULL;
> > +    int img_size = -1;
> > +
> > +    mr = memory_region_find(sysmem, 0, 1).mr;
> > +    if (!mr) {
> > +        error_report("Failed to find memory region at address 0");
> > +        goto out;
>
> <bikeshedpainting>I'd prefer a "return -1 here</bikeshedpainting>

will make the change.

> > +    }
> > +
> > +    ram_ptr = memory_region_get_ram_ptr(mr);
> > +    if (!ram_ptr) {
> > +        error_report("No RAM found");
> > +        goto unref_mr;
> > +    }
> > +
> > +    netboot_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, ipl->netboot_fw);
> > +    if (netboot_filename == NULL) {
> > +        error_report("Could not find network bootloader");
> > +        goto unref_mr;
> > +    }
>
> So you're doing error_report() here already ...
>
> > +    img_size = load_elf_ram(netboot_filename, NULL, NULL, &ipl->start_addr,
> > +                            NULL, NULL, 1, EM_S390, 0, 0, NULL, false);
> > +
> > +    if (img_size < 0) {
> > +        img_size = load_image_size(netboot_filename, ram_ptr, ram_size);
> > +        ipl->start_addr = KERN_IMAGE_START;
> > +    }
> > +
> > +    g_free(netboot_filename);
> > +
> > +unref_mr:
> > +    memory_region_unref(mr);
> > +out:
> > +    return img_size;
> > +}
> > +
> > +static bool is_virtio_net_device(IplParameterBlock *iplb)
> > +{
> > +    uint8_t cssid;
> > +    uint8_t ssid;
> > +    uint16_t devno;
> > +    uint16_t schid;
> > +    SubchDev *sch = NULL;
> > +
> > +    if (iplb->pbt != S390_IPL_TYPE_CCW) {
> > +        return false;
> > +    }
> > +
> > +    devno = be16_to_cpu(iplb->ccw.devno);
> > +    ssid = iplb->ccw.ssid & 3;
> > +
> > +    for (schid = 0; schid < MAX_SCHID; schid++) {
> > +        for (cssid = 0; cssid < MAX_CSSID; cssid++) {
> > +            sch = css_find_subch(1, cssid, ssid, schid);
> > +
> > +            if (sch && sch->devno == devno) {
> > +                return sch->id.cu_model == VIRTIO_ID_NET;
> > +            }
> > +        }
> > +    }
> > +   return false;
> > +}
> > +
> >  void s390_ipl_update_diag308(IplParameterBlock *iplb)
> >  {
> >      S390IPLState *ipl = get_ipl_device();
> >
> >      ipl->iplb = *iplb;
> >      ipl->iplb_valid = true;
> > +    ipl->netboot = is_virtio_net_device(iplb);
> >  }
> >
> >  IplParameterBlock *s390_ipl_get_iplb(void)
> > @@ -298,6 +377,13 @@ void s390_ipl_prepare_cpu(S390CPU *cpu)
> >              ipl->iplb_valid = s390_gen_initial_iplb(ipl);
> >          }
> >      }
> > +    if (ipl->netboot) {
> > +        if (load_netboot_image() < 0) {
> > +            error_report("Failed to load network bootloader");
>
> ... and then you do another error_report here again ... so one error
> gets reported with two error message. Wouldn't it be nicer to rather do
> error_setg(...) in load_netboot_image() and then report only one error
> at this level here?

What would be the advantage of doing that?

Thanks
Farhan


> > +            vm_stop(RUN_STATE_INTERNAL_ERROR);
> > +        }
> > +        ipl->iplb.ccw.netboot_start_addr = ipl->start_addr;
> > +    }
> >  }
> >
> >  static void s390_ipl_reset(DeviceState *dev)
> > diff --git a/hw/s390x/ipl.h b/hw/s390x/ipl.h
> > index 4ad9a7c05e..46930e4c64 100644
> > --- a/hw/s390x/ipl.h
> > +++ b/hw/s390x/ipl.h
> > @@ -16,7 +16,8 @@
> >  #include "cpu.h"
> >
> >  struct IplBlockCcw {
> > -    uint8_t  reserved0[85];
> > +    uint64_t netboot_start_addr;
> > +    uint8_t  reserved0[77];
> >      uint8_t  ssid;
> >      uint16_t devno;
> >      uint8_t  vm_flags;
> > @@ -100,6 +101,7 @@ struct S390IPLState {
> >      IplParameterBlock iplb;
> >      bool iplb_valid;
> >      bool reipl_requested;
> > +    bool netboot;
> >
> >      /*< public >*/
> >      char *kernel;