[PATCH 4/4] efi: add helper functions to insert pmem node for DT fixup

[Ilias Apalodimas]

Hi Heinrich

On Mon, 11 Nov 2024 at 10:08, Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> On 10/25/24 13:14, Sughosh Ganu wrote:
> > The EFI HTTP boot puts the iso installer image at some location in
> > memory which needs to be reserved in the devicetree as persistent
> > memory (pmem). Add helper functions which add this pmem node when the
> > EFI_DT_FIXUP protocol's fixup callback is invoked.
> >
> > Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
> > ---
> >   boot/image-fdt.c             |  9 +++++++++
> >   include/efi_loader.h         | 17 +++++++++++++++++
> >   lib/efi_loader/efi_bootmgr.c | 21 +++++++++++++++++++++
> >   lib/efi_loader/efi_helper.c  | 12 ++++++++++++
> >   4 files changed, 59 insertions(+)
> >
> > diff --git a/boot/image-fdt.c b/boot/image-fdt.c
> > index 8eda521693..b39e81ad30 100644
> > --- a/boot/image-fdt.c
> > +++ b/boot/image-fdt.c
> > @@ -11,6 +11,7 @@
> >   #include <command.h>
> >   #include <fdt_support.h>
> >   #include <fdtdec.h>
> > +#include <efi_loader.h>
> >   #include <env.h>
> >   #include <errno.h>
> >   #include <image.h>
> > @@ -648,6 +649,14 @@ int image_setup_libfdt(struct bootm_headers *images, void *blob, bool lmb)
> >       if (!ft_verify_fdt(blob))
> >               goto err;
> >
> > +     if (CONFIG_IS_ENABLED(EFI_HTTP_BOOT)) {
> > +             fdt_ret = fdt_efi_pmem_setup(blob);
>
> I can see no reason why pmem setup should depend on HTTP boot.

The reason is that we *know* we want to preserve image on HTTP
installers. but we should only add it if that image is booted, not
unconditionally if EFI_HTTP is enabled

>
> It should be possible to pass a memory block device to the kernel no
> matter how it was created.

Yes, we can. But how do we know we need to setup a pmem node? In this
specific case, we know http installers need the image.
If we can find similar rules (or perhaps a command line option), we
can preserve it for all images

Thanks
/Ilias
>
> Best regards
>
> Heinrich
>
> > +             if (fdt_ret) {
> > +                     printf("ERROR: HTTP boot pmem fixup failed\n");
> > +                     goto err;
> > +             }
> > +     }
> > +
> >       /* after here we are using a livetree */
> >       if (!of_live_active() && CONFIG_IS_ENABLED(EVENT)) {
> >               struct event_ft_fixup fixup;
> > diff --git a/include/efi_loader.h b/include/efi_loader.h
> > index d450e304c6..031de18746 100644
> > --- a/include/efi_loader.h
> > +++ b/include/efi_loader.h
> > @@ -748,6 +748,15 @@ bool efi_varname_is_load_option(u16 *var_name16, int *index);
> >   efi_status_t efi_next_variable_name(efi_uintn_t *size, u16 **buf,
> >                                   efi_guid_t *guid);
> >
> > +/**
> > + * fdt_efi_pmem_setup() - Setup the pmem node in the devicetree
> > + *
> > + * @fdt:     Pointer to the devicetree
> > + *
> > + * Return:   0 on success, negative on failure
> > + */
> > +int fdt_efi_pmem_setup(void *fdt);
> > +
> >   /**
> >    * efi_size_in_pages() - convert size in bytes to size in pages
> >    *
> > @@ -964,6 +973,14 @@ efi_status_t efi_set_load_options(efi_handle_t handle,
> >                                 void *load_options);
> >   efi_status_t efi_bootmgr_load(efi_handle_t *handle, void **load_options);
> >
> > +/**
> > + * efi_bootmgr_pmem_setup() - Put a pmem node for UEFI HTTP installers
> > + *
> > + * @fdt:     Pointer to the DT blob
> > + * Return:   status code
> > + */
> > +efi_status_t efi_bootmgr_pmem_setup(void *fdt);
> > +
> >   /**
> >    * struct efi_image_regions - A list of memory regions
> >    *
> > diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> > index 16f75555f6..1d9246be61 100644
> > --- a/lib/efi_loader/efi_bootmgr.c
> > +++ b/lib/efi_loader/efi_bootmgr.c
> > @@ -41,6 +41,8 @@ struct uridp_context {
> >       efi_handle_t mem_handle;
> >   };
> >
> > +static struct uridp_context *uctx;
> > +
> >   const efi_guid_t efi_guid_bootmenu_auto_generated =
> >               EFICONFIG_AUTO_GENERATED_ENTRY_GUID;
> >
> > @@ -423,6 +425,7 @@ efi_status_t efi_bootmgr_release_uridp(struct uridp_context *ctx)
> >
> >       efi_free_pool(ctx->loaded_dp);
> >       free(ctx);
> > +     uctx = NULL;
> >
> >       return ret == EFI_SUCCESS ? ret2 : ret;
> >   }
> > @@ -443,6 +446,23 @@ static void EFIAPI efi_bootmgr_http_return(struct efi_event *event,
> >       EFI_EXIT(ret);
> >   }
> >
> > +/**
> > + * efi_bootmgr_pmem_setup() - Put a pmem node for UEFI HTTP installers
> > + *
> > + * @fdt:     Pointer to the DT blob
> > + * Return:   status code
> > + */
> > +efi_status_t efi_bootmgr_pmem_setup(void *fdt)
> > +{
> > +     if (!uctx) {
> > +             log_warning("No EFI HTTP boot context found\n");
> > +             return EFI_SUCCESS;
> > +     }
> > +
> > +     return !fdt_fixup_pmem_region(fdt, uctx->image_addr, uctx->image_size) ?
> > +             EFI_SUCCESS : EFI_INVALID_PARAMETER;
> > +}
> > +
> >   /**
> >    * try_load_from_uri_path() - Handle the URI device path
> >    *
> > @@ -472,6 +492,7 @@ static efi_status_t try_load_from_uri_path(struct efi_device_path_uri *uridp,
> >       if (!ctx)
> >               return EFI_OUT_OF_RESOURCES;
> >
> > +     uctx = ctx;
> >       s = env_get("loadaddr");
> >       if (!s) {
> >               log_err("Error: loadaddr is not set\n");
> > diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
> > index 00167bd2a1..33cd8b9a50 100644
> > --- a/lib/efi_loader/efi_helper.c
> > +++ b/lib/efi_loader/efi_helper.c
> > @@ -242,6 +242,18 @@ int efi_unlink_dev(efi_handle_t handle)
> >       return 0;
> >   }
> >
> > +/**
> > + * fdt_efi_pmem_setup() - Setup the pmem node in the devicetree
> > + *
> > + * @fdt:     Pointer to the devicetree
> > + *
> > + * Return:   0 on success, negative on failure
> > + */
> > +int fdt_efi_pmem_setup(void *fdt)
> > +{
> > +     return efi_bootmgr_pmem_setup(fdt) == EFI_SUCCESS ? 0 : -1;
> > +}
> > +
> >   static int u16_tohex(u16 c)
> >   {
> >       if (c >= '0' && c <= '9')
>