-/* (end of memory access helper routines) :*/
-
-static void set_ts(void)
-{
- u32 cr0;
-
- cr0 = read_cr0();
- if (!(cr0 & 8))
- write_cr0(cr0|8);
-}
-
-/*S:010
- * We are getting close to the Switcher.
- *
- * Remember that each CPU has two pages which are visible to the Guest when it
- * runs on that CPU. This has to contain the state for that Guest: we copy the
- * state in just before we run the Guest.
- *
- * Each Guest has "changed" flags which indicate what has changed in the Guest
- * since it last ran. We saw this set in interrupts_and_traps.c and
- * segments.c.
- */
-static void copy_in_guest_info(struct lguest *lg, struct lguest_pages *pages)
-{
- /* Copying all this data can be quite expensive. We usually run the
- * same Guest we ran last time (and that Guest hasn't run anywhere else
- * meanwhile). If that's not the case, we pretend everything in the
- * Guest has changed. */
- if (__get_cpu_var(last_guest) != lg || lg->last_pages != pages) {
- __get_cpu_var(last_guest) = lg;
- lg->last_pages = pages;
- lg->changed = CHANGED_ALL;
- }
-
- /* These copies are pretty cheap, so we do them unconditionally: */
- /* Save the current Host top-level page directory. */
- pages->state.host_cr3 = __pa(current->mm->pgd);
- /* Set up the Guest's page tables to see this CPU's pages (and no
- * other CPU's pages). */
- map_switcher_in_guest(lg, pages);
- /* Set up the two "TSS" members which tell the CPU what stack to use
- * for traps which do directly into the Guest (ie. traps at privilege
- * level 1). */
- pages->state.guest_tss.esp1 = lg->esp1;
- pages->state.guest_tss.ss1 = lg->ss1;
-
- /* Copy direct-to-Guest trap entries. */
- if (lg->changed & CHANGED_IDT)
- copy_traps(lg, pages->state.guest_idt, default_idt_entries);
-
- /* Copy all GDT entries which the Guest can change. */
- if (lg->changed & CHANGED_GDT)
- copy_gdt(lg, pages->state.guest_gdt);
- /* If only the TLS entries have changed, copy them. */
- else if (lg->changed & CHANGED_GDT_TLS)
- copy_gdt_tls(lg, pages->state.guest_gdt);
-
- /* Mark the Guest as unchanged for next time. */
- lg->changed = 0;
-}
-
-/* Finally: the code to actually call into the Switcher to run the Guest. */
-static void run_guest_once(struct lguest *lg, struct lguest_pages *pages)
-{
- /* This is a dummy value we need for GCC's sake. */
- unsigned int clobber;
-
- /* Copy the guest-specific information into this CPU's "struct
- * lguest_pages". */
- copy_in_guest_info(lg, pages);
-
- /* Set the trap number to 256 (impossible value). If we fault while
- * switching to the Guest (bad segment registers or bug), this will
- * cause us to abort the Guest. */
- lg->regs->trapnum = 256;
-
- /* Now: we push the "eflags" register on the stack, then do an "lcall".
- * This is how we change from using the kernel code segment to using
- * the dedicated lguest code segment, as well as jumping into the
- * Switcher.
- *
- * The lcall also pushes the old code segment (KERNEL_CS) onto the
- * stack, then the address of this call. This stack layout happens to
- * exactly match the stack of an interrupt... */
- asm volatile("pushf; lcall *lguest_entry"
- /* This is how we tell GCC that %eax ("a") and %ebx ("b")
- * are changed by this routine. The "=" means output. */
- : "=a"(clobber), "=b"(clobber)
- /* %eax contains the pages pointer. ("0" refers to the
- * 0-th argument above, ie "a"). %ebx contains the
- * physical address of the Guest's top-level page
- * directory. */
- : "0"(pages), "1"(__pa(lg->pgdirs[lg->pgdidx].pgdir))
- /* We tell gcc that all these registers could change,
- * which means we don't have to save and restore them in
- * the Switcher. */
- : "memory", "%edx", "%ecx", "%edi", "%esi");
-}