# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxxxx
# Node ID 2ac74e1df3d7d7751a128d2ad2fe9cc3a9d23c54
# Parent ee3d108289370351347f46284024f3347897d2bb
[LINUX] Use new XENMEM_exchange hypercall (where possible)
to provide watertight implementations that should never crash
in ENOMEM situations.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c | 193 +++++++++++++++----------
1 files changed, 122 insertions(+), 71 deletions(-)
diff -r ee3d10828937 -r 2ac74e1df3d7
linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c
--- a/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c Fri Jun 16 14:43:54
2006 +0100
+++ b/linux-2.6-xen-sparse/arch/i386/mm/hypervisor.c Fri Jun 16 14:45:01
2006 +0100
@@ -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;
+ 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();
+ }
+ }
/* 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);
+ 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();
- contiguous_bitmap_set(__pa(vstart) >> PAGE_SHIFT, 1UL << order);
+ if (success)
+ 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));
- set_phys_to_machine((__pa(vstart)>>PAGE_SHIFT)+i, frame);
- }
-
- flush_tlb_all();
-
- 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(unsig
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);
- }
-
- /* 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));
+ out_frames[i] = (__pa(vstart) >> PAGE_SHIFT) + i;
+ }
+
+ /* 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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