Re: [Xen-devel] [v8][PATCH 07/17] hvmloader/util: get reserved device memory maps

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Dec 01, 2014 at 05:24:25PM +0800, Tiejun Chen wrote:
> We need to use reserved device memory maps with multiple times, so
> provide just one common function should be friend.

We need to call reserved device memory maps hypercall
(XENMEM_reserved_device_memory_map) many times, hence provide one common 
function.

> 
> Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> ---
>  tools/firmware/hvmloader/util.c | 59 
> +++++++++++++++++++++++++++++++++++++++++
>  tools/firmware/hvmloader/util.h |  2 ++
>  2 files changed, 61 insertions(+)
> 
> diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
> index 80d822f..dd81fb6 100644
> --- a/tools/firmware/hvmloader/util.c
> +++ b/tools/firmware/hvmloader/util.c
> @@ -22,11 +22,14 @@
>  #include "config.h"
>  #include "hypercall.h"
>  #include "ctype.h"
> +#include "errno.h"
>  #include <stdint.h>
>  #include <xen/xen.h>
>  #include <xen/memory.h>
>  #include <xen/sched.h>
>  
> +struct xen_reserved_device_memory *rdm_map;
> +
>  void wrmsr(uint32_t idx, uint64_t v)
>  {
>      asm volatile (
> @@ -828,6 +831,62 @@ int hpet_exists(unsigned long hpet_base)
>      return ((hpet_id >> 16) == 0x8086);
>  }
>  
> +static int
> +get_reserved_device_memory_map(struct xen_reserved_device_memory entries[],
> +                               uint32_t *max_entries)
> +{
> +    int rc;
> +    struct xen_reserved_device_memory_map xrdmmap = {
> +        .domid = DOMID_SELF,
> +        .nr_entries = *max_entries
> +    };
> +
> +    set_xen_guest_handle(xrdmmap.buffer, entries);
> +
> +    rc = hypercall_memory_op(XENMEM_reserved_device_memory_map, &xrdmmap);
> +    *max_entries = xrdmmap.nr_entries;

Don't you want to check rc first before altering 'max_entries' ?

> +
> +    return rc;
> +}
> +
> +/*
> + * Getting all reserved device memory map info in case of hvmloader.
> + * We just return zero for any failed cases, and this means we
> + * can't further handle any reserved device memory.

That does not sound like the right error value. Why not a proper
return value? At worst you can put 'nr_entries' as an parameter
and return the error value.

> + */
> +unsigned int hvm_get_reserved_device_memory_map(void)
> +{
> +    static unsigned int nr_entries = 0;
> +    int rc = get_reserved_device_memory_map(rdm_map, &nr_entries);
> +
> +    if ( rc == -ENOBUFS )
> +    {
> +        rdm_map = mem_alloc(nr_entries*sizeof(struct 
> xen_reserved_device_memory),

That '*' being squashed looks wrong. Just make it bigger and don't worry about
the 80 line.

> +                            0);
> +        if ( rdm_map )
> +        {
> +            rc = get_reserved_device_memory_map(rdm_map, &nr_entries);
> +            if ( rc )
> +            {
> +                printf("Could not get reserved dev memory info on domain");
> +                return 0;
> +            }
> +        }
> +        else
> +        {
> +            printf("No space to get reserved dev memory maps!\n");
> +            return 0;
> +        }
> +    }
> +    else if ( rc )
> +    {
> +        printf("Could not get reserved dev memory info on domain");
> +        return 0;
> +    }
> +
> +    return nr_entries;
> +}
> +
>  /*
>   * Local variables:
>   * mode: C
> diff --git a/tools/firmware/hvmloader/util.h b/tools/firmware/hvmloader/util.h
> index a70e4aa..e4f1851 100644
> --- a/tools/firmware/hvmloader/util.h
> +++ b/tools/firmware/hvmloader/util.h
> @@ -241,6 +241,8 @@ int build_e820_table(struct e820entry *e820,
>                       unsigned int bios_image_base);
>  void dump_e820_table(struct e820entry *e820, unsigned int nr);
>  
> +unsigned int hvm_get_reserved_device_memory_map(void);
> +
>  #ifndef NDEBUG
>  void perform_tests(void);
>  #else
> -- 
> 1.9.1
> 

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