xen/tools/libxc/xc_hvm_build.c

/******************************************************************************
 * xc_hvm_build.c
 */

#define ELFSIZE 32
#include <stddef.h>
#include <inttypes.h>
#include "xg_private.h"
#include "xc_private.h"
#include "xc_elf.h"
#include <stdlib.h>
#include <unistd.h>
#include <zlib.h>
#include <xen/hvm/hvm_info_table.h>
#include <xen/hvm/params.h>
#include <xen/hvm/e820.h>

#define SCRATCH_PFN 0xFFFFF

#define HVM_LOADER_ENTR_ADDR  0x00100000
static int
parseelfimage(
    char *elfbase, unsigned long elfsize, struct domain_setup_info *dsi);
static int
loadelfimage(
    char *elfbase, int xch, uint32_t dom, unsigned long *parray,
    struct domain_setup_info *dsi);

int xc_set_hvm_param(
    int handle, domid_t dom, int param, unsigned long value)
{
    DECLARE_HYPERCALL;
    xen_hvm_param_t arg;
    int rc;

    hypercall.op     = __HYPERVISOR_hvm_op;
    hypercall.arg[0] = HVMOP_set_param;
    hypercall.arg[1] = (unsigned long)&arg;
    arg.domid = dom;
    arg.index = param;
    arg.value = value;
    if ( lock_pages(&arg, sizeof(arg)) != 0 )
        return -1;
    rc = do_xen_hypercall(handle, &hypercall);
    unlock_pages(&arg, sizeof(arg));
    return rc;
}

int xc_get_hvm_param(
    int handle, domid_t dom, int param, unsigned long *value)
{
    DECLARE_HYPERCALL;
    xen_hvm_param_t arg;
    int rc;

    hypercall.op     = __HYPERVISOR_hvm_op;
    hypercall.arg[0] = HVMOP_get_param;
    hypercall.arg[1] = (unsigned long)&arg;
    arg.domid = dom;
    arg.index = param;
    if ( lock_pages(&arg, sizeof(arg)) != 0 )
        return -1;
    rc = do_xen_hypercall(handle, &hypercall);
    unlock_pages(&arg, sizeof(arg));
    *value = arg.value;
    return rc;
}

static void build_e820map(void *e820_page, unsigned long long mem_size)
{
    struct e820entry *e820entry =
        (struct e820entry *)(((unsigned char *)e820_page) + E820_MAP_OFFSET);
    unsigned long long extra_mem_size = 0;
    unsigned char nr_map = 0;

    /*
     * Physical address space from HVM_BELOW_4G_RAM_END to 4G is reserved
     * for PCI devices MMIO. So if HVM has more than HVM_BELOW_4G_RAM_END
     * RAM, memory beyond HVM_BELOW_4G_RAM_END will go to 4G above.
     */
    if ( mem_size > HVM_BELOW_4G_RAM_END )
    {
        extra_mem_size = mem_size - HVM_BELOW_4G_RAM_END;
        mem_size = HVM_BELOW_4G_RAM_END;
    }

    /* 0x0-0x9F000: Ordinary RAM. */
    e820entry[nr_map].addr = 0x0;
    e820entry[nr_map].size = 0x9F000;
    e820entry[nr_map].type = E820_RAM;
    nr_map++;

    /*
     * 0x9F000-0x9F800: SMBIOS tables.
     * 0x9FC00-0xA0000: Extended BIOS Data Area (EBDA).
     * TODO: SMBIOS tables should be moved higher (>=0xE0000).
     *       They are unusually low in our memory map: could cause problems?
     */
    e820entry[nr_map].addr = 0x9F000;
    e820entry[nr_map].size = 0x1000;
    e820entry[nr_map].type = E820_RESERVED;
    nr_map++;

    /*
     * Following regions are standard regions of the PC memory map.
     * They are not covered by e820 regions. OSes will not use as RAM.
     * 0xA0000-0xC0000: VGA memory-mapped I/O. Not covered by E820.
     * 0xC0000-0xE0000: 16-bit devices, expansion ROMs (inc. vgabios).
     * TODO: hvmloader should free pages which turn out to be unused.
     */

    /*
     * 0xE0000-0x0F0000: PC-specific area. We place ACPI tables here.
     *                   We *cannot* mark as E820_ACPI, for two reasons:
     *                    1. ACPI spec. says that E820_ACPI regions below
     *                       16MB must clip INT15h 0x88 and 0xe801 queries.
     *                       Our rombios doesn't do this.
     *                    2. The OS is allowed to reclaim ACPI memory after
     *                       parsing the tables. But our FACS is in this
     *                       region and it must not be reclaimed (it contains
     *                       the ACPI global lock!).
     * 0xF0000-0x100000: System BIOS.
     * TODO: hvmloader should free pages which turn out to be unused.
     */
    e820entry[nr_map].addr = 0xE0000;
    e820entry[nr_map].size = 0x20000;
    e820entry[nr_map].type = E820_RESERVED;
    nr_map++;

    /* Low RAM goes here. Remove 3 pages for ioreq, bufioreq, and xenstore. */
    e820entry[nr_map].addr = 0x100000;
    e820entry[nr_map].size = mem_size - 0x100000 - PAGE_SIZE * 3;
    e820entry[nr_map].type = E820_RAM;
    nr_map++;

    if ( extra_mem_size )
    {
        e820entry[nr_map].addr = (1ULL << 32);
        e820entry[nr_map].size = extra_mem_size;
        e820entry[nr_map].type = E820_RAM;
        nr_map++;
    }

    *(((unsigned char *)e820_page) + E820_MAP_NR_OFFSET) = nr_map;
}

static int setup_guest(int xc_handle,
                       uint32_t dom, int memsize,
                       char *image, unsigned long image_size,
                       vcpu_guest_context_t *ctxt)
{
    xen_pfn_t *page_array = NULL;
    unsigned long i, nr_pages = (unsigned long)memsize << (20 - PAGE_SHIFT);
    unsigned long shared_page_nr;
    struct xen_add_to_physmap xatp;
    struct shared_info *shared_info;
    void *e820_page;
    struct domain_setup_info dsi;
    uint64_t v_end;
    int rc;

    memset(&dsi, 0, sizeof(struct domain_setup_info));

    if ( (parseelfimage(image, image_size, &dsi)) != 0 )
        goto error_out;

    if ( (dsi.v_kernstart & (PAGE_SIZE - 1)) != 0 )
    {
        PERROR("Guest OS must load to a page boundary.\n");
        goto error_out;
    }

    v_end = (unsigned long long)memsize << 20;

    IPRINTF("VIRTUAL MEMORY ARRANGEMENT:\n"
           "  Loaded HVM loader:    %016"PRIx64"->%016"PRIx64"\n"
           "  TOTAL:                %016"PRIx64"->%016"PRIx64"\n",
           dsi.v_kernstart, dsi.v_kernend,
           dsi.v_start, v_end);
    IPRINTF("  ENTRY ADDRESS:        %016"PRIx64"\n", dsi.v_kernentry);

    if ( (v_end - dsi.v_start) > ((unsigned long long)nr_pages << PAGE_SHIFT) )
    {
        PERROR("Initial guest OS requires too much space: "
               "(%lluMB is greater than %lluMB limit)\n",
               (unsigned long long)(v_end - dsi.v_start) >> 20,
               ((unsigned long long)nr_pages << PAGE_SHIFT) >> 20);
        goto error_out;
    }

    if ( (page_array = malloc(nr_pages * sizeof(xen_pfn_t))) == NULL )
    {
        PERROR("Could not allocate memory.\n");
        goto error_out;
    }

    for ( i = 0; i < nr_pages; i++ )
        page_array[i] = i;
    for ( i = HVM_BELOW_4G_RAM_END >> PAGE_SHIFT; i < nr_pages; i++ )
        page_array[i] += HVM_BELOW_4G_MMIO_LENGTH >> PAGE_SHIFT;

    /* Allocate memory for HVM guest, skipping VGA hole 0xA0000-0xC0000. */
    rc = xc_domain_memory_populate_physmap(
        xc_handle, dom, (nr_pages > 0xa0) ? 0xa0 : nr_pages,
        0, 0, &page_array[0x00]);
    if ( (rc == 0) && (nr_pages > 0xc0) )
        rc = xc_domain_memory_populate_physmap(
            xc_handle, dom, nr_pages - 0xc0, 0, 0, &page_array[0xc0]);
    if ( rc != 0 )
    {
        PERROR("Could not allocate memory for HVM guest.\n");
        goto error_out;
    }

    loadelfimage(image, xc_handle, dom, page_array, &dsi);

    if ( (e820_page = xc_map_foreign_range(
              xc_handle, dom, PAGE_SIZE, PROT_READ | PROT_WRITE,
              E820_MAP_PAGE >> PAGE_SHIFT)) == NULL )
        goto error_out;
    memset(e820_page, 0, PAGE_SIZE);
    build_e820map(e820_page, v_end);
    munmap(e820_page, PAGE_SIZE);

    /* Map and initialise shared_info page. */
    xatp.domid = dom;
    xatp.space = XENMAPSPACE_shared_info;
    xatp.idx   = 0;
    xatp.gpfn  = SCRATCH_PFN;
    if ( (xc_memory_op(xc_handle, XENMEM_add_to_physmap, &xatp) != 0) ||
         ((shared_info = xc_map_foreign_range(
             xc_handle, dom, PAGE_SIZE, PROT_READ | PROT_WRITE,
             SCRATCH_PFN)) == NULL) )
        goto error_out;
    memset(shared_info, 0, PAGE_SIZE);
    for ( i = 0; i < MAX_VIRT_CPUS; i++ )
        shared_info->vcpu_info[i].evtchn_upcall_mask = 1;
    memset(&shared_info->evtchn_mask[0], 0xff,
           sizeof(shared_info->evtchn_mask));
    munmap(shared_info, PAGE_SIZE);

    if ( v_end > HVM_BELOW_4G_RAM_END )
        shared_page_nr = (HVM_BELOW_4G_RAM_END >> PAGE_SHIFT) - 1;
    else
        shared_page_nr = (v_end >> PAGE_SHIFT) - 1;

    /* Paranoia: clean pages. */
    if ( xc_clear_domain_page(xc_handle, dom, shared_page_nr) ||
         xc_clear_domain_page(xc_handle, dom, shared_page_nr-1) ||
         xc_clear_domain_page(xc_handle, dom, shared_page_nr-2) )
        goto error_out;

    xc_set_hvm_param(xc_handle, dom, HVM_PARAM_STORE_PFN, shared_page_nr-1);
    xc_set_hvm_param(xc_handle, dom, HVM_PARAM_BUFIOREQ_PFN, shared_page_nr-2);
    xc_set_hvm_param(xc_handle, dom, HVM_PARAM_IOREQ_PFN, shared_page_nr);

    free(page_array);

    ctxt->user_regs.eip = dsi.v_kernentry;

    return 0;

 error_out:
    free(page_array);
    return -1;
}

static int xc_hvm_build_internal(int xc_handle,
                                 uint32_t domid,
                                 int memsize,
                                 char *image,
                                 unsigned long image_size)
{
    struct xen_domctl launch_domctl;
    vcpu_guest_context_t ctxt;
    int rc;

    if ( (image == NULL) || (image_size == 0) )
    {
        ERROR("Image required");
        goto error_out;
    }

    memset(&ctxt, 0, sizeof(ctxt));

    if ( setup_guest(xc_handle, domid, memsize, image, image_size, &ctxt) < 0 )
    {
        goto error_out;
    }

    if ( lock_pages(&ctxt, sizeof(ctxt) ) )
    {
        PERROR("%s: ctxt mlock failed", __func__);
        goto error_out;
    }

    memset(&launch_domctl, 0, sizeof(launch_domctl));
    launch_domctl.domain = (domid_t)domid;
    launch_domctl.u.vcpucontext.vcpu   = 0;
    set_xen_guest_handle(launch_domctl.u.vcpucontext.ctxt, &ctxt);
    launch_domctl.cmd = XEN_DOMCTL_setvcpucontext;
    rc = xc_domctl(xc_handle, &launch_domctl);

    unlock_pages(&ctxt, sizeof(ctxt));

    return rc;

 error_out:
    return -1;
}

static inline int is_loadable_phdr(Elf32_Phdr *phdr)
{
    return ((phdr->p_type == PT_LOAD) &&
            ((phdr->p_flags & (PF_W|PF_X)) != 0));
}

static int parseelfimage(char *elfbase,
                         unsigned long elfsize,
                         struct domain_setup_info *dsi)
{
    Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfbase;
    Elf32_Phdr *phdr;
    Elf32_Shdr *shdr;
    unsigned long kernstart = ~0UL, kernend=0UL;
    char *shstrtab;
    int h;

    if ( !IS_ELF(*ehdr) )
    {
        xc_set_error(XC_INVALID_KERNEL,
                     "Kernel image does not have an ELF header.");
        return -EINVAL;
    }

    if ( (ehdr->e_phoff + (ehdr->e_phnum * ehdr->e_phentsize)) > elfsize )
    {
        xc_set_error(XC_INVALID_KERNEL,
                     "ELF program headers extend beyond end of image.");
        return -EINVAL;
    }

    if ( (ehdr->e_shoff + (ehdr->e_shnum * ehdr->e_shentsize)) > elfsize )
    {
        xc_set_error(XC_INVALID_KERNEL,
                     "ELF section headers extend beyond end of image.");
        return -EINVAL;
    }

    /* Find the section-header strings table. */
    if ( ehdr->e_shstrndx == SHN_UNDEF )
    {
        xc_set_error(XC_INVALID_KERNEL,
                     "ELF image has no section-header strings table (shstrtab).");
        return -EINVAL;
    }
    shdr = (Elf32_Shdr *)(elfbase + ehdr->e_shoff +
                          (ehdr->e_shstrndx*ehdr->e_shentsize));
    shstrtab = elfbase + shdr->sh_offset;

    for ( h = 0; h < ehdr->e_phnum; h++ )
    {
        phdr = (Elf32_Phdr *)(elfbase + ehdr->e_phoff + (h*ehdr->e_phentsize));
        if ( !is_loadable_phdr(phdr) )
            continue;
        if ( phdr->p_paddr < kernstart )
            kernstart = phdr->p_paddr;
        if ( (phdr->p_paddr + phdr->p_memsz) > kernend )
            kernend = phdr->p_paddr + phdr->p_memsz;
    }

    if ( (kernstart > kernend) ||
         (ehdr->e_entry < kernstart) ||
         (ehdr->e_entry > kernend) )
    {
        xc_set_error(XC_INVALID_KERNEL,
                     "Malformed ELF image.");
        return -EINVAL;
    }

    dsi->v_start = 0x00000000;

    dsi->v_kernstart = kernstart;
    dsi->v_kernend   = kernend;
    dsi->v_kernentry = HVM_LOADER_ENTR_ADDR;

    dsi->v_end       = dsi->v_kernend;

    return 0;
}

static int
loadelfimage(
    char *elfbase, int xch, uint32_t dom, unsigned long *parray,
    struct domain_setup_info *dsi)
{
    Elf32_Ehdr *ehdr = (Elf32_Ehdr *)elfbase;
    Elf32_Phdr *phdr;
    int h;

    char         *va;
    unsigned long pa, done, chunksz;

    for ( h = 0; h < ehdr->e_phnum; h++ )
    {
        phdr = (Elf32_Phdr *)(elfbase + ehdr->e_phoff + (h*ehdr->e_phentsize));
        if ( !is_loadable_phdr(phdr) )
            continue;

        for ( done = 0; done < phdr->p_filesz; done += chunksz )
        {
            pa = (phdr->p_paddr + done) - dsi->v_start;
            if ((va = xc_map_foreign_range(
                xch, dom, PAGE_SIZE, PROT_WRITE,
                parray[pa >> PAGE_SHIFT])) == 0)
                return -1;
            chunksz = phdr->p_filesz - done;
            if ( chunksz > (PAGE_SIZE - (pa & (PAGE_SIZE-1))) )
                chunksz = PAGE_SIZE - (pa & (PAGE_SIZE-1));
            memcpy(va + (pa & (PAGE_SIZE-1)),
                   elfbase + phdr->p_offset + done, chunksz);
            munmap(va, PAGE_SIZE);
        }

        for ( ; done < phdr->p_memsz; done += chunksz )
        {
            pa = (phdr->p_paddr + done) - dsi->v_start;
            if ((va = xc_map_foreign_range(
                xch, dom, PAGE_SIZE, PROT_WRITE,
                parray[pa >> PAGE_SHIFT])) == 0)
                return -1;
            chunksz = phdr->p_memsz - done;
            if ( chunksz > (PAGE_SIZE - (pa & (PAGE_SIZE-1))) )
                chunksz = PAGE_SIZE - (pa & (PAGE_SIZE-1));
            memset(va + (pa & (PAGE_SIZE-1)), 0, chunksz);
            munmap(va, PAGE_SIZE);
        }
    }

    return 0;
}

/* xc_hvm_build
 *
 * Create a domain for a virtualized Linux, using files/filenames
 *
 */

int xc_hvm_build(int xc_handle,
                 uint32_t domid,
                 int memsize,
                 const char *image_name)
{
    char *image;
    int  sts;
    unsigned long image_size;

    if ( (image_name == NULL) ||
         ((image = xc_read_image(image_name, &image_size)) == NULL) )
        return -1;

    sts = xc_hvm_build_internal(xc_handle, domid, memsize, image, image_size);

    free(image);

    return sts;
}

/* xc_hvm_build_mem
 *
 * Create a domain for a virtualized Linux, using buffers
 *
 */

int xc_hvm_build_mem(int xc_handle,
                     uint32_t domid,
                     int memsize,
                     const char *image_buffer,
                     unsigned long image_size)
{
    int           sts;
    unsigned long img_len;
    char         *img;

    /* Validate that there is a kernel buffer */

    if ( (image_buffer == NULL) || (image_size == 0) )
    {
        ERROR("kernel image buffer not present");
        return -1;
    }

    img = xc_inflate_buffer(image_buffer, image_size, &img_len);
    if (img == NULL)
    {
        ERROR("unable to inflate ram disk buffer");
        return -1;
    }

    sts = xc_hvm_build_internal(xc_handle, domid, memsize,
                                img, img_len);

    /* xc_inflate_buffer may return the original buffer pointer (for
       for already inflated buffers), so exercise some care in freeing */

    if ( (img != NULL) && (img != image_buffer) )
        free(img);

    return sts;
}

/*
 * Local variables:
 * mode: C
 * c-set-style: "BSD"
 * c-basic-offset: 4
 * tab-width: 4
 * indent-tabs-mode: nil
 * End:
 */