Re: [Xen-devel] [PATCH RFC] Supporting more than 4 emulated NICs

["Charles Arnold" <carnold@xxxxxxxx>]

Any opinions regarding this patch?

>>> On 5/15/2018 at 11:34 AM, Charles Arnold wrote: 
> Some time ago this bug was written up,
> 
> https://bugs.xenproject.org/xen/bug/46
> "qemu-upstream: limitation on 4 emulated NICs prevents guest from starting
> unless PV override is used."
> 
> While there were some proposed patches and discussion in the bug and on the
> mailing list back in 2014/2015 to address this issue it hasn't seen much
> movement since then.
> 
> The last proposed patch in the bug by Stefano Stabellini is below with some
> small adjustments I've made.
> 
> What is the status of this patch? Does it break migration?
> 
> 
> libxl: account for romfile memory
> 
> Account for memory needed for emulated network card rom files.
> Assume 256K for each romfile.
> 
> Reviewed-by: Charles Arnold <carnold@xxxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
> index f0fd5fd..56a0575 100644
> --- a/tools/libxl/libxl_dom.c
> +++ b/tools/libxl/libxl_dom.c
> @@ -471,7 +471,8 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
>          return ERROR_FAIL;
>      }
>  
> -    if (xc_domain_setmaxmem(ctx->xch, domid, info->target_memkb + size) < 
> 0) {
> +    if (xc_domain_setmaxmem(ctx->xch, domid, info->target_memkb + size
> +       + libxl__get_rom_memory_kb(gc, domid, d_config)) < 0) {
>          LOGE(ERROR, "Couldn't set max memory");
>          return ERROR_FAIL;
>      }
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index c582894..ec99fc0 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -102,8 +102,9 @@
>  #define LIBXL_XENCONSOLE_LIMIT 1048576
>  #define LIBXL_XENCONSOLE_PROTOCOL "vt100"
>  #define LIBXL_MAXMEM_CONSTANT 1024
> +#define LIBXL_ROMSIZE_KB 256
>  #define LIBXL_PV_EXTRA_MEMORY 1024
> -#define LIBXL_HVM_EXTRA_MEMORY 2048
> +#define LIBXL_HVM_EXTRA_MEMORY (LIBXL_MAXMEM_CONSTANT + 1024)
>  #define LIBXL_MIN_DOM0_MEM (128*1024)
>  #define LIBXL_INVALID_GFN (~(uint64_t)0)
>  #define LIBXL_VGA_HOLE_SIZE 0x20
> @@ -1200,6 +1201,13 @@ _hidden char * libxl__domain_pvcontrol_read(libxl__gc 
> *gc,
>  _hidden int libxl__domain_pvcontrol_write(libxl__gc *gc, xs_transaction_t 
> t,
>                                            uint32_t domid, const char *cmd);
>  
> +/* Returns the amount of extra mem required to allocate roms or an libxl
> + * error code on error.
> + * The *d_config parameter is optional.
> + */
> +_hidden int libxl__get_rom_memory_kb(libxl__gc *gc, uint32_t domid,
> +                                     libxl_domain_config *d_config);
> +
>  /* from xl_device */
>  _hidden char *libxl__device_disk_string_of_backend(libxl_disk_backend 
> backend);
>  _hidden char *libxl__device_disk_string_of_format(libxl_disk_format 
> format);
> diff --git a/tools/libxl/libxl_mem.c b/tools/libxl/libxl_mem.c
> index e551e09..b6f9440 100644
> --- a/tools/libxl/libxl_mem.c
> +++ b/tools/libxl/libxl_mem.c
> @@ -17,6 +17,30 @@
>  #include "libxl_internal.h"
>  #include "libxl_arch.h"
>  
> +int libxl__get_rom_memory_kb(libxl__gc *gc, uint32_t domid, 
> libxl_domain_config *d_config)
> +{
> +    int i, count_rom, rc;
> +    libxl_domain_config local_d_config;
> +
> +    if (d_config == NULL) {
> +        libxl_domain_config_init(&local_d_config);
> +        rc = libxl__get_domain_configuration(gc, domid, &local_d_config);
> +        if (rc < 0)
> +            return rc;
> +        d_config = &local_d_config;
> +    }
> +
> +    if (d_config->c_info.type == LIBXL_DOMAIN_TYPE_PV)
> +        return 0;
> +
> +    for (i = 0, count_rom = 0; i < d_config->num_nics; i++) {
> +        if (d_config->nics[i].nictype == LIBXL_NIC_TYPE_VIF_IOEMU)
> +            count_rom++;
> +    }
> +
> +    return count_rom*LIBXL_ROMSIZE_KB;
> +}
> +
>  /*
>   * Set the maximum memory size of the domain in the hypervisor. There is no
>   * change of the current memory size involved. The specified memory size 
> can
> @@ -74,11 +98,13 @@ int libxl_domain_setmaxmem(libxl_ctx *ctx, uint32_t 
> domid, uint64_t max_memkb)
>          goto out;
>      }
>  
> -    rc = xc_domain_setmaxmem(ctx->xch, domid, max_memkb + size);
> +    rc = xc_domain_setmaxmem(ctx->xch, domid, max_memkb + size
> +                             + libxl__get_rom_memory_kb(gc, domid, NULL));
>      if (rc != 0) {
>          LOGED(ERROR, domid,
> -              "xc_domain_setmaxmem domid=%d memkb=%"PRIu64" failed 
> ""rc=%d\n",
> -              domid, max_memkb + size, rc);
> +              "xc_domain_setmaxmem domid=%d memkb=%"PRIu64" failed 
> rc=%d\n",
> +              domid, max_memkb + size +
> +              libxl__get_rom_memory_kb(gc, domid, NULL), rc);
>          goto out;
>      }
>  
> @@ -286,11 +312,12 @@ retry_transaction:
>  
>      if (enforce) {
>          memorykb = new_target_memkb + videoram;
> -        r = xc_domain_setmaxmem(ctx->xch, domid, memorykb + size);
> +        r = xc_domain_setmaxmem(ctx->xch, domid, memorykb + size
> +                + libxl__get_rom_memory_kb(gc, domid, NULL));
>          if (r != 0) {
>              LOGED(ERROR, domid,
>                    "xc_domain_setmaxmem memkb=%"PRIu64" failed ""rc=%d\n",
> -                  memorykb + size,
> +                  memorykb + size + libxl__get_rom_memory_kb(gc, domid, 
> NULL),
>                    r);
>              abort_transaction = 1;
>              rc = ERROR_FAIL;
> 


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