Re: [PATCH v5 02/14] libxc: Prepare a start info structure for hvmloader

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 06/22/2016 01:15 PM, Anthony PERARD wrote:
> ... and load BIOS/UEFI firmware into guest memory.
>
> This adds a new firmware module, system_firmware_module. It is loaded in
> the guest memory and final location is provided to hvmloader via the
> hvm_start_info struct.
>
> This patch create the hvm_start_info struct for HVM guest that have a
> device model, so this is now common code with HVM guest without device
> model.
>
> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
> ---
> CC: boris.ostrovsky@oracle.com
> CC: roger.pau@citrix.com
>
> Changes in V5:
> - in alloc_magic_pages_hvm, check dom->device_model only once instead of
>   twice (fold second if into previous else)
> - rework add_module_to_list to make it easier to read
> - also comment about the intended memory layout of start_info and the
>   modules
> - in bootlate_hvm(), drop start_page and use start_info as they point to
>   the same address
> - rename xc_dom_image.bios_module to xc_dom_image.system_firmware_module
> - rename module name to "firmware" (was "bios")
>
> Changes in V4:
> - change title to suggest the change of beavior
> - remove code to load acpi tables (dsdt)
> - Update public/xen.h about hvm_start_info available on other HVM guest
>   in %ebx.
>
> Changes in V3:
> - rename acpi_table_module to full_acpi_module.
> - factorise module loading, using new function to load existing optinal
>   module, this should not change anything
> - should now use the same code to loads modules as for HVMlite VMs.
>   this avoid duplication of code.
> - no more generic cmdline with a list of modules, each module have its name
>   in the module specific cmdline.
> - scope change for common code between hvmlite and hvmloader
> ---
>  tools/libxc/include/xc_dom.h   |   3 +
>  tools/libxc/xc_dom_hvmloader.c |   3 +
>  tools/libxc/xc_dom_x86.c       | 152 +++++++++++++++++++++++++++++------------
>  xen/include/public/xen.h       |   2 +-
>  4 files changed, 116 insertions(+), 44 deletions(-)
>
> diff --git a/tools/libxc/include/xc_dom.h b/tools/libxc/include/xc_dom.h
> index 6cb10c4..0629971 100644
> --- a/tools/libxc/include/xc_dom.h
> +++ b/tools/libxc/include/xc_dom.h
> @@ -209,6 +209,9 @@ struct xc_dom_image {
>      /* If unset disables the setup of the IOREQ pages. */
>      bool device_model;
>  
> +    /* BIOS/Firmware passed to HVMLOADER */
> +    struct xc_hvm_firmware_module system_firmware_module;
> +
>      /* Extra ACPI tables passed to HVMLOADER */
>      struct xc_hvm_firmware_module acpi_module;
>  
> diff --git a/tools/libxc/xc_dom_hvmloader.c b/tools/libxc/xc_dom_hvmloader.c
> index da8b995..cf2d57c 100644
> --- a/tools/libxc/xc_dom_hvmloader.c
> +++ b/tools/libxc/xc_dom_hvmloader.c
> @@ -167,6 +167,9 @@ static int modules_init(struct xc_dom_image *dom)
>  {
>      int rc;
>  
> +    rc = module_init_one(dom, &dom->system_firmware_module,
> +                         "System Firmware module");
> +    if ( rc ) goto err;
>      rc = module_init_one(dom, &dom->acpi_module, "ACPI module");
>      if ( rc ) goto err;
>      rc = module_init_one(dom, &dom->smbios_module, "SMBIOS module");
> diff --git a/tools/libxc/xc_dom_x86.c b/tools/libxc/xc_dom_x86.c
> index 021f8a8..f017fbd 100644
> --- a/tools/libxc/xc_dom_x86.c
> +++ b/tools/libxc/xc_dom_x86.c
> @@ -69,6 +69,9 @@
>  #define round_up(addr, mask)     ((addr) | (mask))
>  #define round_pg_up(addr)  (((addr) + PAGE_SIZE_X86 - 1) & ~(PAGE_SIZE_X86 - 1))
>  
> +#define HVMLOADER_MODULE_MAX_COUNT 1
> +#define HVMLOADER_MODULE_NAME_SIZE 10
> +
>  struct xc_dom_params {
>      unsigned levels;
>      xen_vaddr_t vaddr_mask;
> @@ -590,6 +593,7 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
>      xen_pfn_t special_array[X86_HVM_NR_SPECIAL_PAGES];
>      xen_pfn_t ioreq_server_array[NR_IOREQ_SERVER_PAGES];
>      xc_interface *xch = dom->xch;
> +    size_t start_info_size = sizeof(struct hvm_start_info);
>  
>      /* Allocate and clear special pages. */
>      for ( i = 0; i < X86_HVM_NR_SPECIAL_PAGES; i++ )
> @@ -624,8 +628,6 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
>  
>      if ( !dom->device_model )
>      {
> -        size_t start_info_size = sizeof(struct hvm_start_info);
> -
>          if ( dom->cmdline )
>          {
>              dom->cmdline_size = ROUNDUP(strlen(dom->cmdline) + 1, 8);
> @@ -635,17 +637,18 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
>          /* Limited to one module. */
>          if ( dom->ramdisk_blob )
>              start_info_size += sizeof(struct hvm_modlist_entry);
> -
> -        rc = xc_dom_alloc_segment(dom, &dom->start_info_seg,
> -                                  "HVMlite start info", 0, start_info_size);
> -        if ( rc != 0 )
> -        {
> -            DOMPRINTF("Unable to reserve memory for the start info");
> -            goto out;
> -        }
>      }
>      else
>      {
> +        start_info_size +=
> +            sizeof(struct hvm_modlist_entry) * HVMLOADER_MODULE_MAX_COUNT;
> +        /*
> +         * Add extra space to write modules name.
> +         * The HVMLOADER_MODULE_NAME_SIZE accounts for NUL byte.
> +         */
> +        start_info_size +=
> +            HVMLOADER_MODULE_NAME_SIZE * HVMLOADER_MODULE_MAX_COUNT;
> +
>          /*
>           * Allocate and clear additional ioreq server pages. The default
>           * server will use the IOREQ and BUFIOREQ special pages above.
> @@ -672,6 +675,14 @@ static int alloc_magic_pages_hvm(struct xc_dom_image *dom)
>                           NR_IOREQ_SERVER_PAGES);
>      }
>  
> +    rc = xc_dom_alloc_segment(dom, &dom->start_info_seg,
> +                              "HVMlite start info", 0, start_info_size);
> +    if ( rc != 0 )
> +    {
> +        DOMPRINTF("Unable to reserve memory for the start info");
> +        goto out;
> +    }
> +
>      /*
>       * Identity-map page table is required for running with CR0.PG=0 when
>       * using Intel EPT. Create a 32-bit non-PAE page directory of superpages.
> @@ -1689,42 +1700,89 @@ static int alloc_pgtables_hvm(struct xc_dom_image *dom)
>      return 0;
>  }
>  
> +/*
> + * The memory layout of the start_info page and the modules, and where the
> + * addresses are stored:
> + *
> + * /----------------------------------\
> + * | struct hvm_start_info            |
> + * +----------------------------------+ <- start_info->modlist_paddr
> + * | struct hvm_modlist_entry[0]      |
> + * +----------------------------------+
> + * | struct hvm_modlist_entry[1]      |
> + * +----------------------------------+ <- modlist[0].cmdline_paddr
> + * | cmdline of module 0              |
> + * | char[HVMLOADER_MODULE_NAME_SIZE] |
> + * +----------------------------------+ <- modlist[1].cmdline_paddr
> + * | cmdline of module 1              |
> + * +----------------------------------+
> + */

Should this go to public/xen.h?

> +static void add_module_to_list(struct xc_dom_image *dom,
> +                               struct xc_hvm_firmware_module *module,
> +                               const char *name,
> +                               struct hvm_modlist_entry *modlist,
> +                               struct hvm_start_info *start_info)
> +{
> +    uint32_t index = start_info->nr_modules;
> +    void *modules_cmdline_start = modlist + HVMLOADER_MODULE_MAX_COUNT;
> +    uint64_t modlist_paddr = (dom->start_info_seg.pfn << PAGE_SHIFT) +
> +        ((uintptr_t)modlist - (uintptr_t)start_info);
> +    uint64_t modules_cmdline_paddr = modlist_paddr +
> +        sizeof(struct hvm_modlist_entry) * HVMLOADER_MODULE_MAX_COUNT;
> +
> +    if ( module->length == 0 )
> +        return;
> +
> +    assert(start_info->nr_modules < HVMLOADER_MODULE_MAX_COUNT);
> +    assert(strnlen(name, HVMLOADER_MODULE_NAME_SIZE)
> +           < HVMLOADER_MODULE_NAME_SIZE);
> +
> +    modlist[index].paddr = module->guest_addr_out;
> +    modlist[index].size = module->length;
> +
> +    strncpy(modules_cmdline_start + HVMLOADER_MODULE_NAME_SIZE * index,
> +            name, HVMLOADER_MODULE_NAME_SIZE);
> +    modlist[index].cmdline_paddr =
> +        modules_cmdline_paddr + HVMLOADER_MODULE_NAME_SIZE * index;
> +
> +    start_info->nr_modules++;
> +}
> +
>  static int bootlate_hvm(struct xc_dom_image *dom)
>  {
>      uint32_t domid = dom->guest_domid;
>      xc_interface *xch = dom->xch;
> +    struct hvm_start_info *start_info;
> +    size_t start_info_size;
> +    struct hvm_modlist_entry *modlist;
>  
> -    if ( !dom->device_model )
> -    {
> -        struct hvm_start_info *start_info;
> -        size_t start_info_size;
> -        void *start_page;
> -
> -        start_info_size = sizeof(*start_info) + dom->cmdline_size;
> -        if ( dom->ramdisk_blob )
> -            start_info_size += sizeof(struct hvm_modlist_entry);
> +    start_info_size = sizeof(*start_info) + dom->cmdline_size;
> +    if ( dom->ramdisk_blob )
> +        start_info_size += sizeof(struct hvm_modlist_entry);
>  
> -        if ( start_info_size >
> -             dom->start_info_seg.pages << XC_DOM_PAGE_SHIFT(dom) )
> -        {
> -            DOMPRINTF("Trying to map beyond start_info_seg");
> -            return -1;
> -        }
> +    if ( start_info_size >
> +         dom->start_info_seg.pages << XC_DOM_PAGE_SHIFT(dom) )
> +    {
> +        DOMPRINTF("Trying to map beyond start_info_seg");
> +        return -1;
> +    }
>  
> -        start_page = xc_map_foreign_range(xch, domid, start_info_size,
> -                                          PROT_READ | PROT_WRITE,
> -                                          dom->start_info_seg.pfn);
> -        if ( start_page == NULL )
> -        {
> -            DOMPRINTF("Unable to map HVM start info page");
> -            return -1;
> -        }
> +    start_info = xc_map_foreign_range(xch, domid, start_info_size,
> +                                      PROT_READ | PROT_WRITE,
> +                                      dom->start_info_seg.pfn);
> +    if ( start_info == NULL )
> +    {
> +        DOMPRINTF("Unable to map HVM start info page");
> +        return -1;
> +    }
>  
> -        start_info = start_page;
> +    modlist = (void*)(start_info + 1) + dom->cmdline_size;
>  
> +    if ( !dom->device_model )
> +    {
>          if ( dom->cmdline )
>          {
> -            char *cmdline = start_page + sizeof(*start_info);
> +            char *cmdline = (void*)(start_info + 1);
>  
>              strncpy(cmdline, dom->cmdline, dom->cmdline_size);
>              start_info->cmdline_paddr = (dom->start_info_seg.pfn << PAGE_SHIFT) +
> @@ -1733,22 +1791,30 @@ static int bootlate_hvm(struct xc_dom_image *dom)
>  
>          if ( dom->ramdisk_blob )
>          {
> -            struct hvm_modlist_entry *modlist =
> -                start_page + sizeof(*start_info) + dom->cmdline_size;
>  
>              modlist[0].paddr = dom->ramdisk_seg.vstart - dom->parms.virt_base;
>              modlist[0].size = dom->ramdisk_seg.vend - dom->ramdisk_seg.vstart;
> -            start_info->modlist_paddr = (dom->start_info_seg.pfn << PAGE_SHIFT) +
> -                                ((uintptr_t)modlist - (uintptr_t)start_info);
>              start_info->nr_modules = 1;
>          }
> -
> -        start_info->magic = XEN_HVM_START_MAGIC_VALUE;
> -
> -        munmap(start_page, start_info_size);
>      }
>      else
>      {
> +        add_module_to_list(dom, &dom->system_firmware_module, "firmware",
> +                           modlist, start_info);
> +    }

Is it possible to add PVH's ramdisk via this routine as well?

-boris

> +
> +    if ( start_info->nr_modules )
> +    {
> +        start_info->modlist_paddr = (dom->start_info_seg.pfn << PAGE_SHIFT) +
> +                            ((uintptr_t)modlist - (uintptr_t)start_info);
> +    }
> +
> +    start_info->magic = XEN_HVM_START_MAGIC_VALUE;
> +
> +    munmap(start_info, start_info_size);
> +
> +    if ( dom->device_model )
> +    {
>          void *hvm_info_page;
>  
>          if ( (hvm_info_page = xc_map_foreign_range(
> diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
> index 37bbb22..d9ddee7 100644
> --- a/xen/include/public/xen.h
> +++ b/xen/include/public/xen.h
> @@ -814,7 +814,7 @@ struct start_info {
>  typedef struct start_info start_info_t;
>  
>  /*
> - * Start of day structure passed to PVH guests in %ebx.
> + * Start of day structure passed to PVH guests and to HVM guests in %ebx.
>   *
>   * NOTE: nothing will be loaded at physical address 0, so a 0 value in any
>   * of the address fields should be treated as not present.



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