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Make shadow IDT a complete IDT with 256 entries.
This simplifies the code a little, in preparation for allowing alternate system call vectors in guests (Plan 9 uses 0x40). Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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48245cc070
commit
56adbe9ddc
2 changed files with 20 additions and 32 deletions
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@ -218,10 +218,9 @@ int deliver_trap(struct lguest *lg, unsigned int num)
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* system calls down from 1750ns to 270ns. Plus, if lguest didn't do it, all
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* the other hypervisors would tease it.
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*
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* This routine determines if a trap can be delivered directly. */
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static int direct_trap(const struct lguest *lg,
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const struct desc_struct *trap,
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unsigned int num)
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* This routine indicates if a particular trap number could be delivered
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* directly. */
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static int direct_trap(unsigned int num)
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{
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/* Hardware interrupts don't go to the Guest at all (except system
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* call). */
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@ -232,14 +231,7 @@ static int direct_trap(const struct lguest *lg,
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* fault address), general protection faults (in/out emulation) and
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* device not available (TS handling), and of course, the hypercall
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* trap. */
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if (num == 14 || num == 13 || num == 7 || num == LGUEST_TRAP_ENTRY)
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return 0;
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/* Only trap gates (type 15) can go direct to the Guest. Interrupt
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* gates (type 14) disable interrupts as they are entered, which we
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* never let the Guest do. Not present entries (type 0x0) also can't
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* go direct, of course 8) */
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return idt_type(trap->a, trap->b) == 0xF;
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return num != 14 && num != 13 && num != 7 && num != LGUEST_TRAP_ENTRY;
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}
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/*:*/
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@ -348,15 +340,11 @@ void load_guest_idt_entry(struct lguest *lg, unsigned int num, u32 lo, u32 hi)
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* to copy this again. */
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lg->changed |= CHANGED_IDT;
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/* The IDT which we keep in "struct lguest" only contains 32 entries
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* for the traps and LGUEST_IRQS (32) entries for interrupts. We
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* ignore attempts to set handlers for higher interrupt numbers, except
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* for the system call "interrupt" at 128: we have a special IDT entry
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* for that. */
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if (num < ARRAY_SIZE(lg->idt))
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/* Check that the Guest doesn't try to step outside the bounds. */
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if (num >= ARRAY_SIZE(lg->idt))
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kill_guest(lg, "Setting idt entry %u", num);
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else
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set_trap(lg, &lg->idt[num], num, lo, hi);
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else if (num == SYSCALL_VECTOR)
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set_trap(lg, &lg->syscall_idt, num, lo, hi);
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}
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/* The default entry for each interrupt points into the Switcher routines which
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@ -399,20 +387,21 @@ void copy_traps(const struct lguest *lg, struct desc_struct *idt,
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/* We can simply copy the direct traps, otherwise we use the default
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* ones in the Switcher: they will return to the Host. */
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for (i = 0; i < FIRST_EXTERNAL_VECTOR; i++) {
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if (direct_trap(lg, &lg->idt[i], i))
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for (i = 0; i < ARRAY_SIZE(lg->idt); i++) {
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/* If no Guest can ever override this trap, leave it alone. */
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if (!direct_trap(i))
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continue;
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/* Only trap gates (type 15) can go direct to the Guest.
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* Interrupt gates (type 14) disable interrupts as they are
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* entered, which we never let the Guest do. Not present
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* entries (type 0x0) also can't go direct, of course. */
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if (idt_type(lg->idt[i].a, lg->idt[i].b) == 0xF)
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idt[i] = lg->idt[i];
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else
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/* Reset it to the default. */
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default_idt_entry(&idt[i], i, def[i]);
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}
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/* Don't forget the system call trap! The IDT entries for other
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* interupts never change, so no need to copy them. */
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i = SYSCALL_VECTOR;
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if (direct_trap(lg, &lg->syscall_idt, i))
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idt[i] = lg->syscall_idt;
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else
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default_idt_entry(&idt[i], i, def[i]);
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}
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void guest_set_clockevent(struct lguest *lg, unsigned long delta)
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@ -184,8 +184,7 @@ struct lguest
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struct desc_struct gdt[GDT_ENTRIES];
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/* The IDT entries: some copied into lguest_ro_state when running. */
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struct desc_struct idt[FIRST_EXTERNAL_VECTOR+LGUEST_IRQS];
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struct desc_struct syscall_idt;
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struct desc_struct idt[IDT_ENTRIES];
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/* Virtual clock device */
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struct hrtimer hrt;
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