Re: [RFC][v3][PATCH 3/6] tools:firmware:hvmloader: reserve RMRR mappings in e820

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 15/08/14 09:27, Tiejun Chen wrote:
> We need to reserve all RMRR mappings in e820 to avoid any
> potential guest memory conflict.
>
> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> ---
>  tools/firmware/hvmloader/e820.c | 94 +++++++++++++++++++++++++++++++++++++++++
>  tools/firmware/hvmloader/e820.h |  6 +++
>  tools/firmware/hvmloader/util.c | 16 +++++++
>  tools/firmware/hvmloader/util.h |  2 +
>  4 files changed, 118 insertions(+)
>
> diff --git a/tools/firmware/hvmloader/e820.c b/tools/firmware/hvmloader/e820.c
> index 2e05e93..7f54eab 100644
> --- a/tools/firmware/hvmloader/e820.c
> +++ b/tools/firmware/hvmloader/e820.c
> @@ -68,12 +68,89 @@ void dump_e820_table(struct e820entry *e820, unsigned int nr)
>      }
>  }

Please apply Xen coding style to all of this file - there are a lot of
errors.

>  
> +static unsigned int construct_rmrr_e820_maps(unsigned int nr,
> +                                     struct rmrr_map *e820_rmrr_map,
> +                                     struct e820entry *e820)
> +{
> +    unsigned int i = 0, j = 0, m = 0, sum_nr = 0;
> +    uint64_t start, end, rmrr_start, rmrr_end;
> +    unsigned int insert = 0, do_insert = 0;
> +
> +do_real_construct:
> +    sum_nr = nr + e820_rmrr_map->nr_map;
> +    for ( i = 0; i < e820_rmrr_map->nr_map; i++ )
> +    {
> +        rmrr_start = e820_rmrr_map->map[i].addr;
> +        rmrr_end = e820_rmrr_map->map[i].addr +
> +                   e820_rmrr_map->map[i].size + 1;
> +
> +        for ( j = 0; j < nr; j++ )
> +        {
> +            end = e820[j].addr + e820[j].size;
> +            start = e820[j+1].addr;
> +
> +            /* Between those existing e820 entries. */
> +            if ( (rmrr_start > end) && (rmrr_end < start) )
> +            {
> +                if (do_insert)
> +                {
> +                    /* Move to free this entry. */
> +                    for ( m = sum_nr - 1; m > j; m-- )
> +                    {
> +                        e820[m].addr = e820[m-1].addr;
> +                        e820[m].size = e820[m-1].size;
> +                        e820[m].type = e820[m-1].type;
> +                    }
> +
> +                    /* Then fill RMRR into that entry. */
> +                    e820[j+1].addr = rmrr_start;
> +                    e820[j+1].size = rmrr_end - rmrr_start;
> +                    e820[j+1].type = E820_RESERVED;
> +                    nr++;
> +                }
> +                insert++;
> +            }
> +            /* Already at the end. */
> +            else if ( (rmrr_start > end) && !start )
> +            {
> +                if (do_insert)
> +                {
> +                    e820[nr].addr = rmrr_start;
> +                    e820[nr].size = rmrr_end - rmrr_start;
> +                    e820[nr].type = E820_RESERVED;
> +                    nr++;
> +                }
> +                insert++;
> +            }
> +        }
> +    }
> +
> +    /* Just return if done. */
> +    if (do_insert)
> +        return nr;
> +
> +    /* Fine to construct RMRR mappings into e820. */
> +    if ( insert == e820_rmrr_map->nr_map)
> +    {
> +        do_insert = 1;
> +        goto do_real_construct;
> +    }
> +    /* Overlap. */
> +    else
> +    {
> +        printf("RMRR overlap with thoese existing e820 entries!\n");
> +        printf("So we don't construct RMRR mapping in e820!\n");
> +    }
> +
> +    return nr;
> +}
>  /* Create an E820 table based on memory parameters provided in hvm_info. */
>  int build_e820_table(struct e820entry *e820,
>                       unsigned int lowmem_reserved_base,
>                       unsigned int bios_image_base)
>  {
>      unsigned int nr = 0;
> +    struct rmrr_map *rmrr_maps;
>  
>      if ( !lowmem_reserved_base )
>              lowmem_reserved_base = 0xA0000;
> @@ -169,6 +246,23 @@ int build_e820_table(struct e820entry *e820,
>          nr++;
>      }
>  
> +    /* We'd better reserve RMRR mapping for each VM to avoid potential
> +     * memory conflict.
> +     */
> +    rmrr_maps = get_rmrr_map_info();
> +    if ( rmrr_maps->nr_map )
> +    {
> +        if ( (nr + rmrr_maps->nr_map) > E820MAX )
> +        {
> +            printf(" No free space to insert all RMRR mapping entry!!\n");
> +            return nr;
> +        }
> +        else
> +        {
> +            nr = construct_rmrr_e820_maps(nr, rmrr_maps, e820);
> +        }
> +    }
> +
>      return nr;
>  }
>  
> diff --git a/tools/firmware/hvmloader/e820.h b/tools/firmware/hvmloader/e820.h
> index b2ead7f..a61b80b 100644
> --- a/tools/firmware/hvmloader/e820.h
> +++ b/tools/firmware/hvmloader/e820.h
> @@ -15,6 +15,12 @@ struct e820entry {
>      uint32_t type;
>  } __attribute__((packed));
>  
> +#define E820MAX 128
> +
> +struct rmrr_map {
> +    unsigned int nr_map;
> +    struct e820entry map[E820MAX];
> +};
>  #endif /* __HVMLOADER_E820_H__ */
>  
>  /*
> diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
> index 80d822f..f63434a 100644
> --- a/tools/firmware/hvmloader/util.c
> +++ b/tools/firmware/hvmloader/util.c
> @@ -766,6 +766,22 @@ struct shared_info *get_shared_info(void)
>      return shared_info;
>  }
>  
> +struct rmrr_map *get_rmrr_map_info(void)
> +{
> +    static int no_rmrr = 1;
> +
> +    if ( no_rmrr == 0 )
> +        return &rmrr_e820map;
> +
> +    if ( hypercall_memory_op(XENMEM_reserved_device_memory_map,
> +                             &rmrr_e820map) != 0 )

This *only* works because you are not passing a xen_rmrr_memory_map_t as
per the hypercall definition, and Xen is clobbering your heap in a way
which matches the hvmloader layout.

> +        BUG();
> +
> +    no_rmrr = 0;
> +
> +    return &rmrr_e820map;
> +}
> +
>  uint16_t get_cpu_mhz(void)
>  {
>      struct shared_info *shared_info = get_shared_info();
> diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
> index a70e4aa..5f48a86 100644
> --- a/tools/firmware/hvmloader/util.h
> +++ b/tools/firmware/hvmloader/util.h
> @@ -236,6 +236,8 @@ unsigned long create_pir_tables(void);
>  void smp_initialise(void);
>  
>  #include "e820.h"
> +struct rmrr_map rmrr_e820map;

Unless I am mistaken, this will put an rmrr_map object named
rmrr_e820map in each translation unit which includes util.h  I suspect
it is not what you actually want to do.

~Andrew

> +struct rmrr_map *get_rmrr_map_info(void);
>  int build_e820_table(struct e820entry *e820,
>                       unsigned int lowmem_reserved_base,
>                       unsigned int bios_image_base);