static int paravirt_put_chars(u32 vtermno, const char *buf, int count)
{
kvm_hypercall3(KVM_HC_MIPS_CONSOLE_OUTPUT, vtermno,
(unsigned long)buf, count);
return count;
}
/*G:037 async_hcall() is pretty simple: I'm quite proud of it really. We have a
* ring buffer of stored hypercalls which the Host will run though next time we
* do a normal hypercall. Each entry in the ring has 4 slots for the hypercall
* arguments, and a "hcall_status" word which is 0 if the call is ready to go,
* and 255 once the Host has finished with it.
*
* If we come around to a slot which hasn't been finished, then the table is
* full and we just make the hypercall directly. This has the nice side
* effect of causing the Host to run all the stored calls in the ring buffer
* which empties it for next time! */
static void async_hcall(unsigned long call, unsigned long arg1,
unsigned long arg2, unsigned long arg3)
{
/* Note: This code assumes we're uniprocessor. */
static unsigned int next_call;
unsigned long flags;
/* Disable interrupts if not already disabled: we don't want an
* interrupt handler making a hypercall while we're already doing
* one! */
local_irq_save(flags);
if (lguest_data.hcall_status[next_call] != 0xFF) {
/* Table full, so do normal hcall which will flush table. */
kvm_hypercall3(call, arg1, arg2, arg3);
} else {
lguest_data.hcalls[next_call].arg0 = call;
lguest_data.hcalls[next_call].arg1 = arg1;
lguest_data.hcalls[next_call].arg2 = arg2;
lguest_data.hcalls[next_call].arg3 = arg3;
/* Arguments must all be written before we mark it to go */
wmb();
lguest_data.hcall_status[next_call] = 0;
if (++next_call == LHCALL_RING_SIZE)
next_call = 0;
}
local_irq_restore(flags);
}
/*
* Emit one character to the boot console.
*/
int prom_putchar(char c)
{
kvm_hypercall3(KVM_HC_MIPS_CONSOLE_OUTPUT, 0 /* port 0 */,
(unsigned long)&c, 1 /* len == 1 */);
return 1;
}
/*
* For a single GDT entry which changes, we do the lazy thing: alter our GDT,
* then tell the Host to reload the entire thing. This operation is so rare
* that this naive implementation is reasonable.
*/
static void lguest_write_gdt_entry(struct desc_struct *dt, int entrynum,
const void *desc, int type)
{
native_write_gdt_entry(dt, entrynum, desc, type);
/* Tell Host about this new entry. */
kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, entrynum,
dt[entrynum].a, dt[entrynum].b);
}
/*
* The Global Descriptor Table.
*
* The Intel architecture defines another table, called the Global Descriptor
* Table (GDT). You tell the CPU where it is (and its size) using the "lgdt"
* instruction, and then several other instructions refer to entries in the
* table. There are three entries which the Switcher needs, so the Host simply
* controls the entire thing and the Guest asks it to make changes using the
* LOAD_GDT hypercall.
*
* This is the exactly like the IDT code.
*/
static void lguest_load_gdt(const struct desc_ptr *desc)
{
unsigned int i;
struct desc_struct *gdt = (void *)desc->address;
for (i = 0; i < (desc->size+1)/8; i++)
kvm_hypercall3(LHCALL_LOAD_GDT_ENTRY, i, gdt[i].a, gdt[i].b);
}
static void lazy_hcall3(unsigned long call,
unsigned long arg1,
unsigned long arg2,
unsigned long arg3)
{
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_NONE)
kvm_hypercall3(call, arg1, arg2, arg3);
else
async_hcall(call, arg1, arg2, arg3, 0);
}
/*G:034
* The Interrupt Descriptor Table (IDT).
*
* The IDT tells the processor what to do when an interrupt comes in. Each
* entry in the table is a 64-bit descriptor: this holds the privilege level,
* address of the handler, and... well, who cares? The Guest just asks the
* Host to make the change anyway, because the Host controls the real IDT.
*/
static void lguest_write_idt_entry(gate_desc *dt,
int entrynum, const gate_desc *g)
{
/* The gate_desc structure is 8 bytes long: we hand it to the Host in
* two 32-bit chunks. The whole 32-bit kernel used to hand descriptors
* around like this; typesafety wasn't a big concern in Linux's early
* years. */
u32 *desc = (u32 *)g;
/* Keep the local copy up to date. */
native_write_idt_entry(dt, entrynum, g);
/* Tell Host about this new entry. */
kvm_hypercall3(LHCALL_LOAD_IDT_ENTRY, entrynum, desc[0], desc[1]);
}
static void kvm_mmu_op(void *buffer, unsigned len)
{
int r;
unsigned long a1, a2;
do {
a1 = __pa(buffer);
a2 = 0; /* on i386 __pa() always returns <4G */
r = kvm_hypercall3(KVM_HC_MMU_OP, len, a1, a2);
buffer += r;
len -= r;
} while (len);
}
