Re: [PATCH 2/3] xen/x86: bzImage parse kernel_alignment

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 6 Mar 2024, Jason Andryuk wrote:
> Expand bzimage_parse() to return kernel_alignment from the setup_header.
> This will be needed if loading a PVH kernel at a physical offset to
> compensate for a reserved E820 region.
> 
> Signed-off-by: Jason Andryuk <jason.andryuk@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  xen/arch/x86/bzimage.c             | 4 +++-
>  xen/arch/x86/hvm/dom0_build.c      | 4 +++-
>  xen/arch/x86/include/asm/bzimage.h | 3 +--
>  xen/arch/x86/pv/dom0_build.c       | 2 +-
>  4 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/x86/bzimage.c b/xen/arch/x86/bzimage.c
> index ac4fd428be..0f4cfc49f7 100644
> --- a/xen/arch/x86/bzimage.c
> +++ b/xen/arch/x86/bzimage.c
> @@ -105,7 +105,7 @@ unsigned long __init bzimage_headroom(void *image_start,
>  }
>  
>  int __init bzimage_parse(void *image_base, void **image_start,
> -                         unsigned long *image_len)
> +                         unsigned long *image_len, unsigned int *align)
>  {
>      struct setup_header *hdr = (struct setup_header *)(*image_start);
>      int err = bzimage_check(hdr, *image_len);
> @@ -118,6 +118,8 @@ int __init bzimage_parse(void *image_base, void 
> **image_start,
>      {
>          *image_start += (hdr->setup_sects + 1) * 512 + hdr->payload_offset;
>          *image_len = hdr->payload_length;
> +        if ( align )
> +            *align = hdr->kernel_alignment;
>      }
>  
>      if ( elf_is_elfbinary(*image_start, *image_len) )
> diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
> index 0ceda4140b..bbae8a5645 100644
> --- a/xen/arch/x86/hvm/dom0_build.c
> +++ b/xen/arch/x86/hvm/dom0_build.c
> @@ -548,12 +548,14 @@ static int __init pvh_load_kernel(struct domain *d, 
> const module_t *image,
>      struct elf_binary elf;
>      struct elf_dom_parms parms;
>      paddr_t last_addr;
> +    unsigned int align = 0;
>      struct hvm_start_info start_info = { 0 };
>      struct hvm_modlist_entry mod = { 0 };
>      struct vcpu *v = d->vcpu[0];
>      int rc;
>  
> -    if ( (rc = bzimage_parse(image_base, &image_start, &image_len)) != 0 )
> +    rc = bzimage_parse(image_base, &image_start, &image_len, &align);
> +    if ( rc != 0 )
>      {
>          printk("Error trying to detect bz compressed kernel\n");
>          return rc;
> diff --git a/xen/arch/x86/include/asm/bzimage.h 
> b/xen/arch/x86/include/asm/bzimage.h
> index 7ed69d3910..de4e9a446f 100644
> --- a/xen/arch/x86/include/asm/bzimage.h
> +++ b/xen/arch/x86/include/asm/bzimage.h
> @@ -4,8 +4,7 @@
>  #include <xen/init.h>
>  
>  unsigned long bzimage_headroom(void *image_start, unsigned long 
> image_length);
> -
>  int bzimage_parse(void *image_base, void **image_start,
> -                  unsigned long *image_len);
> +                  unsigned long *image_len, unsigned int *align);
>  
>  #endif /* __X86_BZIMAGE_H__ */
> diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
> index d8043fa58a..e9fa8a9a82 100644
> --- a/xen/arch/x86/pv/dom0_build.c
> +++ b/xen/arch/x86/pv/dom0_build.c
> @@ -416,7 +416,7 @@ int __init dom0_construct_pv(struct domain *d,
>  
>      d->max_pages = ~0U;
>  
> -    if ( (rc = bzimage_parse(image_base, &image_start, &image_len)) != 0 )
> +    if ( (rc = bzimage_parse(image_base, &image_start, &image_len, NULL)) != 
> 0 )
>          return rc;
>  
>      if ( (rc = elf_init(&elf, image_start, image_len)) != 0 )
> -- 
> 2.44.0
> 
>