Re: [Xen-devel] [PATCH for-next 08/16] xen/arm: kernel: Rework kernel_zimage_load to use the generic copy helper

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 23 Nov 2017, Julien Grall wrote:
> The function kernel_zimage is dealing with IPA but uses gvirt_to_maddr to
> do the translation. This is currently working fine because the stage-1 MMU
> is disabled.
> 
> Furthermore, the function is implementing its own copy to guest resulting
> in code duplication and making more difficult to update the logic in
> page-tables (such support for Populate On Demand).
> 
> The new copy_to_guest_phys_flush_dcache could be used here by
> temporarily mapping the full kernel in the virtual space.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> ---
>  xen/arch/arm/domain_build.c |  1 +
>  xen/arch/arm/kernel.c       | 33 ++++++++++++---------------------
>  xen/arch/arm/kernel.h       |  2 ++
>  3 files changed, 15 insertions(+), 21 deletions(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index c74f4dd69d..3f87bf2051 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -2133,6 +2133,7 @@ int construct_dom0(struct domain *d)
>      d->max_pages = ~0U;
>  
>      kinfo.unassigned_mem = dom0_mem;
> +    kinfo.d = d;
>  
>      rc = kernel_probe(&kinfo);
>      if ( rc < 0 )
> diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
> index a6c6413712..2fb0b9684d 100644
> --- a/xen/arch/arm/kernel.c
> +++ b/xen/arch/arm/kernel.c
> @@ -15,6 +15,8 @@
>  #include <xen/gunzip.h>
>  #include <xen/vmap.h>
>  
> +#include <asm/guest_access.h>
> +
>  #include "kernel.h"
>  
>  #define UIMAGE_MAGIC          0x27051956
> @@ -157,7 +159,8 @@ static void kernel_zimage_load(struct kernel_info *info)
>      paddr_t load_addr = kernel_zimage_place(info);
>      paddr_t paddr = info->zimage.kernel_addr;
>      paddr_t len = info->zimage.len;
> -    unsigned long offs;
> +    void *kernel;
> +    int rc;
>  
>      info->entry = load_addr;
>  
> @@ -165,29 +168,17 @@ static void kernel_zimage_load(struct kernel_info *info)
>  
>      printk("Loading zImage from %"PRIpaddr" to %"PRIpaddr"-%"PRIpaddr"\n",
>             paddr, load_addr, load_addr + len);
> -    for ( offs = 0; offs < len; )
> -    {
> -        uint64_t par;
> -        paddr_t s, l, ma = 0;
> -        void *dst;
> -
> -        s = offs & ~PAGE_MASK;
> -        l = min(PAGE_SIZE - s, len);
> -
> -        par = gvirt_to_maddr(load_addr + offs, &ma, GV2M_WRITE);
> -        if ( par )
> -        {
> -            panic("Unable to map translate guest address");
> -            return;
> -        }
>  
> -        dst = map_domain_page(maddr_to_mfn(ma));
> +    kernel = ioremap_wc(paddr, len);

Why ioremap_wc?


> +    if ( !kernel )
> +        panic("Unable to map the hwdom kernel");
>  
> -        copy_from_paddr(dst + s, paddr + offs, l);
> +    rc = copy_to_guest_phys_flush_dcache(info->d, load_addr,
> +                                         kernel, len);
> +    if ( rc != 0 )
> +        panic("Unable to copy the kernel in the hwdom memory");
>  
> -        unmap_domain_page(dst);
> -        offs += l;
> -    }
> +    iounmap(kernel);
>  }
>  
>  /*
> diff --git a/xen/arch/arm/kernel.h b/xen/arch/arm/kernel.h
> index c1b07d4f7b..6d695097b5 100644
> --- a/xen/arch/arm/kernel.h
> +++ b/xen/arch/arm/kernel.h
> @@ -15,6 +15,8 @@ struct kernel_info {
>      enum domain_type type;
>  #endif
>  
> +    struct domain *d;
> +
>      void *fdt; /* flat device tree */
>      paddr_t unassigned_mem; /* RAM not (yet) assigned to a bank */
>      struct meminfo mem;
> -- 
> 2.11.0
> 

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