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[LINUX] Use new XENMEM_exchange hypercall (where possible)

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to provide watertight implementations that should never crash
in ENOMEM situations.
Signed-off-by: Keir Fraser <keir@xensource.com>
This commit is contained in:
kfraser@dhcp93.uk.xensource.com committed 2006-06-16 14:45:01 +01:00
1 parent 516250dac6
commit a2ee238fcf
1 file changed
+120 -69
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linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c
+120 -69
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@@ -263,6 +263,10 @@ static void contiguous_bitmap_clear(
}
}
/* Protected by balloon_lock. */
#define MAX_CONTIG_ORDER 7
static unsigned long discontig_frames[1<<MAX_CONTIG_ORDER];
/* Ensure multi-page extents are contiguous in machine memory. */
int xen_create_contiguous_region(
unsigned long vstart, unsigned int order, unsigned int address_bits)
@@ -271,13 +275,23 @@ int xen_create_contiguous_region(
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
unsigned long *in_frames = discontig_frames, out_frame;
unsigned long frame, i, flags;
struct xen_memory_reservation reservation = {
.nr_extents = 1,
.extent_order = 0,
.domid = DOMID_SELF
long rc;
int success;
struct xen_memory_exchange exchange = {
.in = {
.nr_extents = 1UL << order,
.extent_order = 0,
.domid = DOMID_SELF
},
.out = {
.nr_extents = 1,
.extent_order = order,
.address_bits = address_bits,
.domid = DOMID_SELF
}
};
set_xen_guest_handle(reservation.extent_start, &frame);
/*
* Currently an auto-translated guest will not perform I/O, nor will
@@ -287,68 +301,73 @@ int xen_create_contiguous_region(
if (xen_feature(XENFEAT_auto_translated_physmap))
return 0;
if (order > MAX_CONTIG_ORDER)
return -ENOMEM;
set_xen_guest_handle(exchange.in.extent_start, in_frames);
set_xen_guest_handle(exchange.out.extent_start, &out_frame);
scrub_pages(vstart, 1 << order);
balloon_lock(flags);
/* 1. Zap current PTEs, giving away the underlying pages. */
for (i = 0; i < (1<<order); i++) {
/* 1. Zap current PTEs, remembering MFNs. */
for (i = 0; i < (1UL<<order); i++) {
pgd = pgd_offset_k(vstart + (i*PAGE_SIZE));
pud = pud_offset(pgd, (vstart + (i*PAGE_SIZE)));
pmd = pmd_offset(pud, (vstart + (i*PAGE_SIZE)));
pte = pte_offset_kernel(pmd, (vstart + (i*PAGE_SIZE)));
frame = pte_mfn(*pte);
BUG_ON(HYPERVISOR_update_va_mapping(
vstart + (i*PAGE_SIZE), __pte_ma(0), 0));
in_frames[i] = pte_mfn(*pte);
if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
__pte_ma(0), 0))
BUG();
set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i,
INVALID_P2M_ENTRY);
BUG_ON(HYPERVISOR_memory_op(
XENMEM_decrease_reservation, &reservation) != 1);
}
/* 2. Get a new contiguous memory extent. */
reservation.extent_order = order;
reservation.address_bits = address_bits;
frame = __pa(vstart) >> PAGE_SHIFT;
if (HYPERVISOR_memory_op(XENMEM_populate_physmap,
&reservation) != 1)
goto fail;
/* 3. Map the new extent in place of old pages. */
for (i = 0; i < (1<<order); i++) {
BUG_ON(HYPERVISOR_update_va_mapping(
vstart + (i*PAGE_SIZE),
pfn_pte_ma(frame+i, PAGE_KERNEL), 0));
set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame+i);
out_frame = __pa(vstart) >> PAGE_SHIFT;
rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
success = (exchange.nr_exchanged == (1UL << order));
BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
BUG_ON(success && (rc != 0));
if (unlikely(rc == -ENOSYS)) {
/* Compatibility when XENMEM_exchange is unsupported. */
if (HYPERVISOR_memory_op(XENMEM_decrease_reservation,
&exchange.in) != (1UL << order))
BUG();
success = (HYPERVISOR_memory_op(XENMEM_populate_physmap,
&exchange.out) == 1);
if (!success) {
/* Couldn't get special memory: fall back to normal. */
for (i = 0; i < (1UL<<order); i++)
in_frames[i] = (__pa(vstart)>>PAGE_SHIFT) + i;
if (HYPERVISOR_memory_op(XENMEM_populate_physmap,
&exchange.in) != (1UL<<order))
BUG();
}
}
flush_tlb_all();
contiguous_bitmap_set(__pa(vstart) >> PAGE_SHIFT, 1UL << order);
balloon_unlock(flags);
return 0;
fail:
reservation.extent_order = 0;
reservation.address_bits = 0;
for (i = 0; i < (1<<order); i++) {
frame = (__pa(vstart) >> PAGE_SHIFT) + i;
BUG_ON(HYPERVISOR_memory_op(
XENMEM_populate_physmap, &reservation) != 1);
BUG_ON(HYPERVISOR_update_va_mapping(
vstart + (i*PAGE_SIZE),
pfn_pte_ma(frame, PAGE_KERNEL), 0));
/* 3. Map the new extent in place of old pages. */
for (i = 0; i < (1UL<<order); i++) {
frame = success ? (out_frame + i) : in_frames[i];
if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
pfn_pte_ma(frame,
PAGE_KERNEL),
0))
BUG();
set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame);
}
flush_tlb_all();
if (success)
contiguous_bitmap_set(__pa(vstart) >> PAGE_SHIFT,
1UL << order);
balloon_unlock(flags);
return -ENOMEM;
return success ? 0 : -ENOMEM;
}
void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
@@ -357,47 +376,79 @@ void xen_destroy_contiguous_region(unsigned long vstart, unsigned int order)
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
unsigned long *out_frames = discontig_frames, in_frame;
unsigned long frame, i, flags;
struct xen_memory_reservation reservation = {
.nr_extents = 1,
.extent_order = 0,
.domid = DOMID_SELF
long rc;
int success;
struct xen_memory_exchange exchange = {
.in = {
.nr_extents = 1,
.extent_order = order,
.domid = DOMID_SELF
},
.out = {
.nr_extents = 1UL << order,
.extent_order = 0,
.domid = DOMID_SELF
}
};
set_xen_guest_handle(reservation.extent_start, &frame);
if (xen_feature(XENFEAT_auto_translated_physmap) ||
!test_bit(__pa(vstart) >> PAGE_SHIFT, contiguous_bitmap))
return;
if (order > MAX_CONTIG_ORDER)
return;
set_xen_guest_handle(exchange.in.extent_start, &in_frame);
set_xen_guest_handle(exchange.out.extent_start, out_frames);
scrub_pages(vstart, 1 << order);
balloon_lock(flags);
contiguous_bitmap_clear(__pa(vstart) >> PAGE_SHIFT, 1UL << order);
/* 1. Zap current PTEs, giving away the underlying pages. */
for (i = 0; i < (1<<order); i++) {
pgd = pgd_offset_k(vstart + (i*PAGE_SIZE));
pud = pud_offset(pgd, (vstart + (i*PAGE_SIZE)));
pmd = pmd_offset(pud, (vstart + (i*PAGE_SIZE)));
pte = pte_offset_kernel(pmd, (vstart + (i*PAGE_SIZE)));
frame = pte_mfn(*pte);
BUG_ON(HYPERVISOR_update_va_mapping(
vstart + (i*PAGE_SIZE), __pte_ma(0), 0));
/* 1. Find start MFN of contiguous extent. */
pgd = pgd_offset_k(vstart);
pud = pud_offset(pgd, vstart);
pmd = pmd_offset(pud, vstart);
pte = pte_offset_kernel(pmd, vstart);
in_frame = pte_mfn(*pte);
/* 2. Zap current PTEs. */
for (i = 0; i < (1UL<<order); i++) {
if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
__pte_ma(0), 0));
set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i,
INVALID_P2M_ENTRY);
BUG_ON(HYPERVISOR_memory_op(
XENMEM_decrease_reservation, &reservation) != 1);
out_frames[i] = (__pa(vstart) >> PAGE_SHIFT) + i;
}
/* 2. Map new pages in place of old pages. */
for (i = 0; i < (1<<order); i++) {
frame = (__pa(vstart) >> PAGE_SHIFT) + i;
BUG_ON(HYPERVISOR_memory_op(
XENMEM_populate_physmap, &reservation) != 1);
BUG_ON(HYPERVISOR_update_va_mapping(
vstart + (i*PAGE_SIZE),
pfn_pte_ma(frame, PAGE_KERNEL), 0));
/* 3. Do the exchange for non-contiguous MFNs. */
rc = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
success = (exchange.nr_exchanged == 1);
BUG_ON(!success && ((exchange.nr_exchanged != 0) || (rc == 0)));
BUG_ON(success && (rc != 0));
if (rc == -ENOSYS) {
/* Compatibility when XENMEM_exchange is unsupported. */
if (HYPERVISOR_memory_op(XENMEM_decrease_reservation,
&exchange.in) != 1)
BUG();
if (HYPERVISOR_memory_op(XENMEM_populate_physmap,
&exchange.out) != (1UL << order))
BUG();
success = 1;
}
/* 4. Map new pages in place of old pages. */
for (i = 0; i < (1UL<<order); i++) {
frame = success ? out_frames[i] : (in_frame + i);
if (HYPERVISOR_update_va_mapping(vstart + (i*PAGE_SIZE),
pfn_pte_ma(frame,
PAGE_KERNEL),
0))
BUG();
set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame);
}
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