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xen/stubdom/grub/kexec.c
T
Keir Fraser a2c7db64f5 Add PV-GRUB 
This fetches GRUB1 sources, applies the {graphical, print function,
save default, and ext3_256byte} patches from debian, and applies a
patch to make it work on x86_64 and port it to Mini-OS.  By using
libxc, PV-GRUB can then "kexec" the loaded kernel from inside the
domain itself, hence permitting to avoid the security-concerned
pygrub.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>
2008-06-18 09:36:47 +01:00

325 lines
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/*
* This supports booting another PV kernel from Mini-OS
*
* The idea is to setup it using libxc, answer to day0 memory allocation
* requests, and using a trampoline boot page to switch to the new page table.
*
* The procedure of the boot page is:
* - map itself at the target position (that may overwrite some C stuff, but we
* do not care any more)
* - jump there
* - switch to the target page table
* - unpin the old page table
* - jump to the new kernel
*
* Samuel Thibault <Samuel.Thibault@eu.citrix.com>, May 2008
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <xenctrl.h>
#include <xc_dom.h>
#include <kernel.h>
#include <console.h>
#include <os.h>
#include <blkfront.h>
#include <netfront.h>
#include <fbfront.h>
#include <shared.h>
#include "mini-os.h"
#if 0
#define DEBUG(fmt, ...) printk(fmt, ## __VA_ARGS__)
#else
#define DEBUG(fmt, ...) (void)0
#endif
/* Assembly boot page from boot.S */
extern void _boot_page;
extern pgentry_t _boot_page_entry;
extern unsigned long _boot_pdmfn;
extern unsigned long _boot_stack, _boot_target, _boot_start_info, _boot_start;
extern xen_pfn_t _boot_oldpdmfn;
extern void _boot(void);
static unsigned long *pages;
static unsigned long *pages_mfns;
static unsigned long allocated;
int pin_table(int xc_handle, unsigned int type, unsigned long mfn,
domid_t dom);
/* We need mfn to appear as target_pfn, so exchange with the MFN there */
static void do_exchange(struct xc_dom_image *dom, xen_pfn_t target_pfn, xen_pfn_t source_mfn)
{
xen_pfn_t source_pfn;
xen_pfn_t target_mfn;
for (source_pfn = 0; source_pfn < start_info.nr_pages; source_pfn++)
if (dom->p2m_host[source_pfn] == source_mfn)
break;
ASSERT(source_pfn < start_info.nr_pages);
target_mfn = dom->p2m_host[target_pfn];
/* Put target MFN at source PFN */
dom->p2m_host[source_pfn] = target_mfn;
/* Put source MFN at target PFN */
dom->p2m_host[target_pfn] = source_mfn;
}
int kexec_allocate(struct xc_dom_image *dom, xen_vaddr_t up_to)
{
unsigned long new_allocated = (up_to - dom->parms.virt_base) / PAGE_SIZE;
unsigned long i;
pages = realloc(pages, new_allocated * sizeof(*pages));
pages_mfns = realloc(pages_mfns, new_allocated * sizeof(*pages_mfns));
for (i = allocated; i < new_allocated; i++) {
/* Exchange old page of PFN i with a newly allocated page. */
xen_pfn_t old_mfn = dom->p2m_host[i];
xen_pfn_t new_pfn;
xen_pfn_t new_mfn;
pages[i] = alloc_page();
memset((void*) pages[i], 0, PAGE_SIZE);
new_pfn = PHYS_PFN(to_phys(pages[i]));
pages_mfns[i] = new_mfn = pfn_to_mfn(new_pfn);
/* Put old page at new PFN */
dom->p2m_host[new_pfn] = old_mfn;
/* Put new page at PFN i */
dom->p2m_host[i] = new_mfn;
}
allocated = new_allocated;
return 0;
}
void kexec(void *kernel, long kernel_size, void *module, long module_size, char *cmdline)
{
struct xc_dom_image *dom;
int rc;
domid_t domid = DOMID_SELF;
xen_pfn_t pfn;
int xc_handle;
unsigned long i;
void *seg;
xen_pfn_t boot_page_mfn = virt_to_mfn(&_boot_page);
char features[] = "";
struct mmu_update *m2p_updates;
unsigned long nr_m2p_updates;
DEBUG("booting with cmdline %s\n", cmdline);
xc_handle = xc_interface_open();
dom = xc_dom_allocate(cmdline, features);
dom->allocate = kexec_allocate;
dom->kernel_blob = kernel;
dom->kernel_size = kernel_size;
dom->ramdisk_blob = module;
dom->ramdisk_size = module_size;
dom->flags = 0;
dom->console_evtchn = start_info.console.domU.evtchn;
dom->xenstore_evtchn = start_info.store_evtchn;
if ( (rc = xc_dom_boot_xen_init(dom, xc_handle, domid)) != 0 ) {
grub_printf("xc_dom_boot_xen_init returned %d\n", rc);
errnum = ERR_BOOT_FAILURE;
goto out;
}
if ( (rc = xc_dom_parse_image(dom)) != 0 ) {
grub_printf("xc_dom_parse_image returned %d\n", rc);
errnum = ERR_BOOT_FAILURE;
goto out;
}
#ifdef __i386__
if (strcmp(dom->guest_type, "xen-3.0-x86_32p")) {
grub_printf("can only boot x86 32 PAE kernels, not %s\n", dom->guest_type);
errnum = ERR_EXEC_FORMAT;
goto out;
}
#endif
#ifdef __x86_64__
if (strcmp(dom->guest_type, "xen-3.0-x86_64")) {
grub_printf("can only boot x86 64 kernels, not %s\n", dom->guest_type);
errnum = ERR_EXEC_FORMAT;
goto out;
}
#endif
/* equivalent of xc_dom_mem_init */
dom->arch_hooks = xc_dom_find_arch_hooks(dom->guest_type);
dom->total_pages = start_info.nr_pages;
/* equivalent of arch_setup_meminit */
/* setup initial p2m */
dom->p2m_host = malloc(sizeof(*dom->p2m_host) * dom->total_pages);
/* Start with our current P2M */
for (i = 0; i < dom->total_pages; i++)
dom->p2m_host[i] = pfn_to_mfn(i);
if ( (rc = xc_dom_build_image(dom)) != 0 ) {
grub_printf("xc_dom_build_image returned %d\n", rc);
errnum = ERR_BOOT_FAILURE;
goto out;
}
/* copy hypercall page */
/* TODO: domctl instead, but requires privileges */
if (dom->parms.virt_hypercall != -1) {
pfn = PHYS_PFN(dom->parms.virt_hypercall - dom->parms.virt_base);
memcpy((void *) pages[pfn], hypercall_page, PAGE_SIZE);
}
/* Equivalent of xc_dom_boot_image */
dom->shared_info_mfn = PHYS_PFN(start_info.shared_info);
if (!xc_dom_compat_check(dom)) {
grub_printf("xc_dom_compat_check failed\n");
errnum = ERR_EXEC_FORMAT;
goto out;
}
/* Move current console, xenstore and boot MFNs to the allocated place */
do_exchange(dom, dom->console_pfn, start_info.console.domU.mfn);
do_exchange(dom, dom->xenstore_pfn, start_info.store_mfn);
DEBUG("virt base at %llx\n", dom->parms.virt_base);
DEBUG("bootstack_pfn %lx\n", dom->bootstack_pfn);
_boot_target = dom->parms.virt_base + PFN_PHYS(dom->bootstack_pfn);
DEBUG("_boot_target %lx\n", _boot_target);
do_exchange(dom, PHYS_PFN(_boot_target - dom->parms.virt_base),
virt_to_mfn(&_boot_page));
/* Make sure the bootstrap page table does not RW-map any of our current
* page table frames */
kexec_allocate(dom, dom->virt_pgtab_end);
if ( (rc = xc_dom_update_guest_p2m(dom))) {
grub_printf("xc_dom_update_guest_p2m returned %d\n", rc);
errnum = ERR_BOOT_FAILURE;
goto out;
}
if ( dom->arch_hooks->setup_pgtables )
if ( (rc = dom->arch_hooks->setup_pgtables(dom))) {
grub_printf("setup_pgtables returned %d\n", rc);
errnum = ERR_BOOT_FAILURE;
goto out;
}
/* start info page */
#undef start_info
if ( dom->arch_hooks->start_info )
dom->arch_hooks->start_info(dom);
#define start_info (start_info_union.start_info)
xc_dom_log_memory_footprint(dom);
/* Unmap libxc's projection of the boot page table */
seg = xc_dom_seg_to_ptr(dom, &dom->pgtables_seg);
munmap(seg, dom->pgtables_seg.vend - dom->pgtables_seg.vstart);
/* Unmap day0 pages to avoid having a r/w mapping of the future page table */
for (pfn = 0; pfn < allocated; pfn++)
munmap((void*) pages[pfn], PAGE_SIZE);
/* Pin the boot page table base */
if ( (rc = pin_table(dom->guest_xc,
#ifdef __i386__
MMUEXT_PIN_L3_TABLE,
#endif
#ifdef __x86_64__
MMUEXT_PIN_L4_TABLE,
#endif
xc_dom_p2m_host(dom, dom->pgtables_seg.pfn),
dom->guest_domid)) != 0 ) {
grub_printf("pin_table(%lx) returned %d\n", xc_dom_p2m_host(dom,
dom->pgtables_seg.pfn), rc);
errnum = ERR_BOOT_FAILURE;
goto out_remap;
}
/* We populate the Mini-OS page table here so that boot.S can just call
* update_va_mapping to project itself there. */
need_pgt(_boot_target);
DEBUG("day0 pages %lx\n", allocated);
DEBUG("boot target page %lx\n", _boot_target);
DEBUG("boot page %p\n", &_boot_page);
DEBUG("boot page mfn %lx\n", boot_page_mfn);
_boot_page_entry = PFN_PHYS(boot_page_mfn) | L1_PROT;
DEBUG("boot page entry %llx\n", _boot_page_entry);
_boot_oldpdmfn = virt_to_mfn(start_info.pt_base);
DEBUG("boot old pd mfn %lx\n", _boot_oldpdmfn);
DEBUG("boot pd virt %lx\n", dom->pgtables_seg.vstart);
_boot_pdmfn = dom->p2m_host[PHYS_PFN(dom->pgtables_seg.vstart - dom->parms.virt_base)];
DEBUG("boot pd mfn %lx\n", _boot_pdmfn);
_boot_stack = _boot_target + PAGE_SIZE;
DEBUG("boot stack %lx\n", _boot_stack);
_boot_start_info = dom->parms.virt_base + PFN_PHYS(dom->start_info_pfn);
DEBUG("boot start info %lx\n", _boot_start_info);
_boot_start = dom->parms.virt_entry;
DEBUG("boot start %lx\n", _boot_start);
/* Keep only useful entries */
for (nr_m2p_updates = pfn = 0; pfn < start_info.nr_pages; pfn++)
if (dom->p2m_host[pfn] != pfn_to_mfn(pfn))
nr_m2p_updates++;
m2p_updates = malloc(sizeof(*m2p_updates) * nr_m2p_updates);
for (i = pfn = 0; pfn < start_info.nr_pages; pfn++)
if (dom->p2m_host[pfn] != pfn_to_mfn(pfn)) {
m2p_updates[i].ptr = PFN_PHYS(dom->p2m_host[pfn]) | MMU_MACHPHYS_UPDATE;
m2p_updates[i].val = pfn;
i++;
}
for (i = 0; i < blk_nb; i++)
shutdown_blkfront(blk_dev[i]);
if (net_dev)
shutdown_netfront(net_dev);
if (kbd_dev)
shutdown_kbdfront(kbd_dev);
stop_kernel();
/* Update M2P */
if ((rc = HYPERVISOR_mmu_update(m2p_updates, nr_m2p_updates, NULL, DOMID_SELF)) < 0) {
xprintk("Could not update M2P\n");
ASSERT(0);
}
xprintk("go!\n");
/* Jump to trampoline boot page */
_boot();
ASSERT(0);
out_remap:
for (pfn = 0; pfn < allocated; pfn++)
do_map_frames(pages[pfn], &pages_mfns[pfn], 1, 0, 0, DOMID_SELF, 0, L1_PROT);
out:
xc_dom_release(dom);
for (pfn = 0; pfn < allocated; pfn++)
free_page((void*)pages[pfn]);
free(pages);
free(pages_mfns);
pages = NULL;
pages_mfns = NULL;
allocated = 0;
xc_interface_close(xc_handle );
}
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