/* Load a new IDT into Xen. In principle this can be per-CPU, so we
hold a spinlock to protect the static traps[] array (static because
it avoids allocation, and saves stack space). */
static void xen_load_idt(const struct desc_ptr *desc)
{
static DEFINE_SPINLOCK(lock);
static struct trap_info traps[257];
trace_xen_cpu_load_idt(desc);
spin_lock(&lock);
__get_cpu_var(idt_desc) = *desc;
xen_convert_trap_info(desc, traps);
xen_mc_flush();
if (HYPERVISOR_set_trap_table(traps))
BUG();
spin_unlock(&lock);
}
struct multicall_space __xen_mc_entry(size_t args)
{
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
struct multicall_space ret;
unsigned argspace = (args + sizeof(u64) - 1) / sizeof(u64);
BUG_ON(preemptible());
BUG_ON(argspace > MC_ARGS);
if (b->mcidx == MC_BATCH ||
(b->argidx + argspace) > MC_ARGS)
xen_mc_flush();
ret.mc = &b->entries[b->mcidx];
b->mcidx++;
ret.args = &b->args[b->argidx];
b->argidx += argspace;
return ret;
}
/* Write a GDT descriptor entry. Ignore LDT descriptors, since
they're handled differently. */
static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
const void *desc, int type)
{
preempt_disable();
switch (type) {
case DESC_LDT:
case DESC_TSS:
/* ignore */
break;
default: {
xmaddr_t maddr = arbitrary_virt_to_machine(&dt[entry]);
xen_mc_flush();
if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
BUG();
}
}
preempt_enable();
}
struct multicall_space __xen_mc_entry(size_t args)
{
struct mc_buffer *b = &__get_cpu_var(mc_buffer);
struct multicall_space ret;
unsigned argidx = roundup(b->argidx, sizeof(u64));
BUG_ON(preemptible());
BUG_ON(b->argidx > MC_ARGS);
if (b->mcidx == MC_BATCH ||
(argidx + args) > MC_ARGS) {
mc_stats_flush(b->mcidx == MC_BATCH ? FL_SLOTS : FL_ARGS);
xen_mc_flush();
argidx = roundup(b->argidx, sizeof(u64));
}
ret.mc = &b->entries[b->mcidx];
b->mcidx++;
ret.args = &b->args[argidx];
b->argidx = argidx + args;
BUG_ON(b->argidx > MC_ARGS);
return ret;
}
static void xen_end_context_switch(struct task_struct *next)
{
xen_mc_flush();
paravirt_end_context_switch(next);
}
int m2p_remove_override(struct page *page, bool clear_pte)
{
unsigned long flags;
unsigned long mfn;
unsigned long pfn;
unsigned long uninitialized_var(address);
unsigned level;
pte_t *ptep = NULL;
int ret = 0;
pfn = page_to_pfn(page);
mfn = get_phys_to_machine(pfn);
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
return -EINVAL;
if (!PageHighMem(page)) {
address = (unsigned long)__va(pfn << PAGE_SHIFT);
ptep = lookup_address(address, &level);
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
"m2p_remove_override: pfn %lx not mapped", pfn))
return -EINVAL;
}
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
WARN_ON(!PagePrivate(page));
ClearPagePrivate(page);
if (clear_pte) {
struct gnttab_map_grant_ref *map_op =
(struct gnttab_map_grant_ref *) page->index;
set_phys_to_machine(pfn, map_op->dev_bus_addr);
if (!PageHighMem(page)) {
struct multicall_space mcs;
struct gnttab_unmap_grant_ref *unmap_op;
/*
* It might be that we queued all the m2p grant table
* hypercalls in a multicall, then m2p_remove_override
* get called before the multicall has actually been
* issued. In this case handle is going to -1 because
* it hasn't been modified yet.
*/
if (map_op->handle == -1)
xen_mc_flush();
/*
* Now if map_op->handle is negative it means that the
* hypercall actually returned an error.
*/
if (map_op->handle == GNTST_general_error) {
printk(KERN_WARNING "m2p_remove_override: "
"pfn %lx mfn %lx, failed to modify kernel mappings",
pfn, mfn);
return -1;
}
mcs = xen_mc_entry(
sizeof(struct gnttab_unmap_grant_ref));
unmap_op = mcs.args;
unmap_op->host_addr = map_op->host_addr;
unmap_op->handle = map_op->handle;
unmap_op->dev_bus_addr = 0;
MULTI_grant_table_op(mcs.mc,
GNTTABOP_unmap_grant_ref, unmap_op, 1);
xen_mc_issue(PARAVIRT_LAZY_MMU);
set_pte_at(&init_mm, address, ptep,
pfn_pte(pfn, PAGE_KERNEL));
__flush_tlb_single(address);
map_op->host_addr = 0;
}
} else
set_phys_to_machine(pfn, page->index);
/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
* somewhere in this domain, even before being added to the
* m2p_override (see comment above in m2p_add_override).
* If there are no other entries in the m2p_override corresponding
* to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
* the original pfn (the one shared by the frontend): the backend
* cannot do any IO on this page anymore because it has been
* unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
* the original pfn causes mfn_to_pfn(mfn) to return the frontend
* pfn again. */
mfn &= ~FOREIGN_FRAME_BIT;
ret = __get_user(pfn, &machine_to_phys_mapping[mfn]);
if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) &&
m2p_find_override(mfn) == NULL)
set_phys_to_machine(pfn, mfn);
return 0;
}
void xen_leave_lazy(void)
{
paravirt_leave_lazy(paravirt_get_lazy_mode());
xen_mc_flush();
}
static int m2p_remove_override(struct page *page,
struct gnttab_map_grant_ref *kmap_op,
unsigned long mfn)
{
unsigned long flags;
unsigned long pfn;
unsigned long uninitialized_var(address);
unsigned level;
pte_t *ptep = NULL;
pfn = page_to_pfn(page);
if (!PageHighMem(page)) {
address = (unsigned long)__va(pfn << PAGE_SHIFT);
ptep = lookup_address(address, &level);
if (WARN(ptep == NULL || level != PG_LEVEL_4K,
"m2p_remove_override: pfn %lx not mapped", pfn))
return -EINVAL;
}
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
if (kmap_op != NULL) {
if (!PageHighMem(page)) {
struct multicall_space mcs;
struct gnttab_unmap_and_replace *unmap_op;
struct page *scratch_page = get_balloon_scratch_page();
unsigned long scratch_page_address = (unsigned long)
__va(page_to_pfn(scratch_page) << PAGE_SHIFT);
/*
* It might be that we queued all the m2p grant table
* hypercalls in a multicall, then m2p_remove_override
* get called before the multicall has actually been
* issued. In this case handle is going to -1 because
* it hasn't been modified yet.
*/
if (kmap_op->handle == -1)
xen_mc_flush();
/*
* Now if kmap_op->handle is negative it means that the
* hypercall actually returned an error.
*/
if (kmap_op->handle == GNTST_general_error) {
pr_warn("m2p_remove_override: pfn %lx mfn %lx, failed to modify kernel mappings",
pfn, mfn);
put_balloon_scratch_page();
return -1;
}
xen_mc_batch();
mcs = __xen_mc_entry(
sizeof(struct gnttab_unmap_and_replace));
unmap_op = mcs.args;
unmap_op->host_addr = kmap_op->host_addr;
unmap_op->new_addr = scratch_page_address;
unmap_op->handle = kmap_op->handle;
MULTI_grant_table_op(mcs.mc,
GNTTABOP_unmap_and_replace, unmap_op, 1);
mcs = __xen_mc_entry(0);
MULTI_update_va_mapping(mcs.mc, scratch_page_address,
pfn_pte(page_to_pfn(scratch_page),
PAGE_KERNEL_RO), 0);
xen_mc_issue(PARAVIRT_LAZY_MMU);
kmap_op->host_addr = 0;
put_balloon_scratch_page();
}
}
/* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present
* somewhere in this domain, even before being added to the
* m2p_override (see comment above in m2p_add_override).
* If there are no other entries in the m2p_override corresponding
* to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for
* the original pfn (the one shared by the frontend): the backend
* cannot do any IO on this page anymore because it has been
* unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of
* the original pfn causes mfn_to_pfn(mfn) to return the frontend
* pfn again. */
mfn &= ~FOREIGN_FRAME_BIT;
pfn = mfn_to_pfn_no_overrides(mfn);
if (__pfn_to_mfn(pfn) == FOREIGN_FRAME(mfn) &&
m2p_find_override(mfn) == NULL)
set_phys_to_machine(pfn, mfn);
return 0;
}