[SeaBIOS] [PATCH v5 3/5] QEMU fw_cfg: Add command to write back address of file

[Igor Mammedov]

On Mon, 20 Feb 2017 10:43:46 +0100
Laszlo Ersek <lersek at redhat.com> wrote:

> On 02/18/17 07:21, ben at skyportsystems.com wrote:
> > From: Ben Warren <ben at skyportsystems.com>
> > 
> > This command is similar to ADD_POINTER, but instead of patching
> > memory, it writes the pointer back to QEMU over the DMA interface.
> > 
> > Signed-off-by: Ben Warren <ben at skyportsystems.com>
> > ---
> >  src/fw/romfile_loader.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
> >  src/fw/romfile_loader.h | 23 ++++++++++++++++++++---
> >  2 files changed, 65 insertions(+), 3 deletions(-)  
> 
> Reviewed-by: Laszlo Ersek <lersek at redhat.com>
Reviewed-by: Igor Mammedov <imammedo at redhat.com>

> 
> Thanks
> Laszlo
> 
> > diff --git a/src/fw/romfile_loader.c b/src/fw/romfile_loader.c
> > index 7737453..30e7b58 100644
> > --- a/src/fw/romfile_loader.c
> > +++ b/src/fw/romfile_loader.c
> > @@ -5,6 +5,7 @@
> >  #include "romfile.h" // struct romfile_s
> >  #include "malloc.h" // Zone*, _malloc
> >  #include "output.h" // warn_*
> > +#include "paravirt.h" // qemu_cfg_write_file
> >  
> >  struct romfile_loader_file {
> >      struct romfile_s *file;
> > @@ -127,6 +128,46 @@ err:
> >      warn_internalerror();
> >  }
> >  
> > +static void romfile_loader_write_pointer(struct romfile_loader_entry_s *entry,
> > +                                         struct romfile_loader_files *files)
> > +{
> > +    struct romfile_s *dest_file;
> > +    struct romfile_loader_file *src_file;
> > +    unsigned dst_offset = le32_to_cpu(entry->wr_pointer.dst_offset);
> > +    unsigned src_offset = le32_to_cpu(entry->wr_pointer.src_offset);
> > +    u64 pointer = 0;
> > +
> > +    /* Writing back to a file that may not be loaded in RAM */
> > +    dest_file = romfile_find(entry->wr_pointer.dest_file);
> > +    src_file = romfile_loader_find(entry->wr_pointer.src_file, files);
> > +
> > +    if (!dest_file || !src_file || !src_file->data ||
> > +        dst_offset + entry->wr_pointer.size < dst_offset ||
> > +        dst_offset + entry->wr_pointer.size > dest_file->size ||
> > +        src_offset >= src_file->file->size ||
> > +        entry->wr_pointer.size < 1 || entry->wr_pointer.size > 8 ||
> > +        entry->wr_pointer.size & (entry->wr_pointer.size - 1)) {
> > +        goto err;
> > +    }
> > +
> > +    pointer = (unsigned long)src_file->data + src_offset;
> > +    /* Make sure the pointer fits within wr_pointer.size */
> > +    if ((entry->wr_pointer.size != sizeof(u64)) &&
> > +        ((pointer >> (entry->wr_pointer.size * 8)) > 0)) {
> > +        goto err;
> > +    }
> > +    pointer = cpu_to_le64(pointer);
> > +
> > +    /* Only supported on QEMU */
> > +    if (qemu_cfg_write_file(&pointer, dest_file, dst_offset,
> > +                            entry->wr_pointer.size) != entry->wr_pointer.size) {
> > +        goto err;
> > +    }
> > +    return;
> > + err:
> > +    warn_internalerror();
> > +}
> > +
> >  int romfile_loader_execute(const char *name)
> >  {
> >      struct romfile_loader_entry_s *entry;
> > @@ -161,6 +202,10 @@ int romfile_loader_execute(const char *name)
> >                          break;
> >                  case ROMFILE_LOADER_COMMAND_ADD_CHECKSUM:
> >                          romfile_loader_add_checksum(entry, files);
> > +                        break;
> > +                case ROMFILE_LOADER_COMMAND_WRITE_POINTER:
> > +                        romfile_loader_write_pointer(entry, files);
> > +                        break;
> >                  default:
> >                          /* Skip commands that we don't recognize. */
> >                          break;
> > diff --git a/src/fw/romfile_loader.h b/src/fw/romfile_loader.h
> > index bce3719..4dc50ab 100644
> > --- a/src/fw/romfile_loader.h
> > +++ b/src/fw/romfile_loader.h
> > @@ -51,15 +51,32 @@ struct romfile_loader_entry_s {
> >              u32 length;
> >          } cksum;
> >  
> > +        /*
> > +         * COMMAND_WRITE_POINTER - Write back to a host file via DMA,
> > +         * @wr_pointer.dest_file at offset @wr_pointer.dst_offset, a pointer
> > +         * to the table originating from @wr_pointer.src_file at offset
> > +         * @wr_pointer.src_offset.
> > +         * 1,2,4 or 8 byte unsigned addition is used depending on
> > +         * @wr_pointer.size.
> > +         */
> > +        struct {
> > +            char dest_file[ROMFILE_LOADER_FILESZ];
> > +            char src_file[ROMFILE_LOADER_FILESZ];
> > +            u32 dst_offset;
> > +            u32 src_offset;
> > +            u8 size;
> > +        } wr_pointer;
> > +
> >          /* padding */
> >          char pad[124];
> >      };
> >  };
> >  
> >  enum {
> > -    ROMFILE_LOADER_COMMAND_ALLOCATE     = 0x1,
> > -    ROMFILE_LOADER_COMMAND_ADD_POINTER  = 0x2,
> > -    ROMFILE_LOADER_COMMAND_ADD_CHECKSUM = 0x3,
> > +    ROMFILE_LOADER_COMMAND_ALLOCATE      = 0x1,
> > +    ROMFILE_LOADER_COMMAND_ADD_POINTER   = 0x2,
> > +    ROMFILE_LOADER_COMMAND_ADD_CHECKSUM  = 0x3,
> > +    ROMFILE_LOADER_COMMAND_WRITE_POINTER = 0x4,
> >  };
> >  
> >  enum {
> >   
> 
> 
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