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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v2 8/8] xen: arm: allocate more than one bank for 1:1 domain 0 if needed
Depending on where Xen and the initial modules were loaded into RAM we may not
be able to allocate a suitably contiguous block of memory for dom0. Especially
since the allocations made by alloc_domheap_pages are naturally aligned (e.g. a
1GB allocation must be at a 1GB boundary).
The alignment requirement in particular is a huge limitation, meaning that even
dom0_mem0=1G on a 2GB system is pretty likely to fail unless you are very
careful with your load addresses. People were also having trouble with dom0 >
128MB on the 1GB cubieboard2 when using fairly standard load addresses for
things.
This patch tries to allocate multiple banks of memory in order to try and
satisfy the entire requested domain 0 allocation. Sadly this turns out to be
pretty tricky to arrange (see the large comment in the code).
Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Karim Raslan <karim.allah.ahmed@xxxxxxxxx>
---
v2: New patch
---
xen/arch/arm/domain_build.c | 278 +++++++++++++++++++++++++++++++++++++++----
1 file changed, 256 insertions(+), 22 deletions(-)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 46a3619..f37127f 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -44,6 +44,13 @@ custom_param("dom0_mem", parse_dom0_mem);
# define DPRINT(fmt, args...) do {} while ( 0 )
#endif
+//#define DEBUG_11_ALLOCATION
+#ifdef DEBUG_11_ALLOCATION
+# define D11PRINT(fmt, args...) printk(XENLOG_DEBUG fmt, ##args)
+#else
+# define D11PRINT(fmt, args...) do {} while ( 0 )
+#endif
+
/*
* Amount of extra space required to dom0's device tree. No new nodes
* are added (yet) but one terminating reserve map entry (16 bytes) is
@@ -66,39 +73,266 @@ struct vcpu *__init alloc_dom0_vcpu0(struct domain *dom0)
return alloc_vcpu(dom0, 0, 0);
}
-static void allocate_memory_11(struct domain *d, struct kernel_info *kinfo)
+static unsigned int get_11_allocation_size(paddr_t size)
{
- paddr_t start;
- paddr_t size;
- struct page_info *pg;
- unsigned int order = get_order_from_bytes(dom0_mem);
- int res;
- paddr_t spfn;
+ /*
+ * get_order_from_bytes returns the order greater than or equal to
+ * the given size, but we need less than or equal. Adding one to
+ * the size pushes an evenly aligned size into the next order, so
+ * we can then unconditionally subtract 1 from the order which is
+ * returned.
+ */
+ return get_order_from_bytes(size + 1) - 1;
+}
- if ( is_32bit_domain(d) )
- pg = alloc_domheap_pages(d, order, MEMF_bits(32));
- else
- pg = alloc_domheap_pages(d, order, 0);
- if ( !pg )
- panic("Failed to allocate contiguous memory for dom0");
+/*
+ * Insert the given pages into a memory bank, banks are ordered by address.
+ *
+ * Returns false if the memory would be below bank 0.
+ */
+static bool_t insert_11_bank(struct domain *d,
+ struct kernel_info *kinfo,
+ struct page_info *pg,
+ unsigned int order)
+{
+ int res, i;
+ paddr_t spfn;
+ paddr_t start, size;
spfn = page_to_mfn(pg);
start = pfn_to_paddr(spfn);
size = pfn_to_paddr((1 << order));
- // 1:1 mapping
- printk("Populate P2M %#"PRIx64"->%#"PRIx64" (1:1 mapping for dom0)\n",
- start, start + size);
- res = guest_physmap_add_page(d, spfn, spfn, order);
+ D11PRINT("Allocated %#"PRIpaddr"-%#"PRIpaddr" (%ldMB/%ldMB, order %d)\n",
+ start, start + size,
+ 1UL << (order+PAGE_SHIFT-20),
+ /* Don't want format this as PRIpaddr (16 digit hex) */
+ (unsigned long)(kinfo->unassigned_mem >> 20),
+ order);
- if ( res )
- panic("Unable to add pages in DOM0: %d", res);
+ if ( kinfo->mem.nr_banks > 0 && start + size < kinfo->mem.bank[0].start )
+ {
+ D11PRINT("Allocation is below bank 0, not using\n");
+ free_domheap_pages(pg, order);
+ return false;
+ }
- kinfo->mem.bank[0].start = start;
- kinfo->mem.bank[0].size = size;
- kinfo->mem.nr_banks = 1;
+ res = guest_physmap_add_page(d, spfn, spfn, order);
+ if ( res )
+ panic("Failed map pages to DOM0: %d", res);
kinfo->unassigned_mem -= size;
+
+ if ( kinfo->mem.nr_banks == 0 )
+ {
+ kinfo->mem.bank[0].start = start;
+ kinfo->mem.bank[0].size = size;
+ kinfo->mem.nr_banks = 1;
+ return true;
+ }
+
+ for( i = 0; i < kinfo->mem.nr_banks; i++ )
+ {
+ struct membank *bank = &kinfo->mem.bank[i];
+
+ /* If possible merge new memory into the start of the bank */
+ if ( bank->start == start+size )
+ {
+ bank->start = start;
+ bank->size += size;
+ return true;
+ }
+
+ /* If possible merge new memory onto the end of the bank */
+ if ( start == bank->start + bank->size )
+ {
+ bank->size += size;
+ return true;
+ }
+
+ /*
+ * Otherwise if it is below this bank insert new memory in a
+ * new bank before this one. If there was a lower bank we
+ * could have inserted the memory into/before we would already
+ * have done so, so this must be the right place.
+ */
+ if ( start + size < bank->start && kinfo->mem.nr_banks < NR_MEM_BANKS )
+ {
+ memmove(bank + 1, bank, sizeof(*bank)*(kinfo->mem.nr_banks - i));
+ kinfo->mem.nr_banks++;
+ bank->start = start;
+ bank->size = size;
+ return true;
+ }
+ }
+
+ if ( i == kinfo->mem.nr_banks && kinfo->mem.nr_banks < NR_MEM_BANKS )
+ {
+ struct membank *bank = &kinfo->mem.bank[kinfo->mem.nr_banks];
+
+ bank->start = start;
+ bank->size = size;
+ kinfo->mem.nr_banks++;
+ return true;
+ }
+
+ panic("Failed add pages to DOM0 memory bank");
+}
+
+/*
+ * This is all pretty horrible.
+ *
+ * Requirements:
+ *
+ * 1. The dom0 kernel should be loaded within the first 128MB of RAM. This
+ * is necessary at least for Linux zImage kernels, which are all we
+ * support today.
+ * 2. We want to put the dom0 kernel, ramdisk and DTB in the same
+ * bank. Partly this is just easier for us to deal with, but also
+ * the ramdisk and DTB must be placed within a certain proximity of
+ * the kernel within RAM.
+ * 3. For 32-bit dom0 we want to place as much of the RAM as we
+ * reasonably can below 4GB, so that it can be used by non-LPAE
+ * enabled kernels.
+ * 4. For 32-bit dom0 the kernel must be located below 4GB.
+ * 5. We want to have a few largers banks rather than many smaller ones.
+ *
+ * For the first two requirements we need to make sure that the lowest
+ * bank is sufficiently large.
+ *
+ * For convenience we also sort the banks by physical address.
+ *
+ * The memory allocator does not really give us the flexibility to
+ * meet these requirements directly. So instead of proceed as follows:
+ *
+ * We first allocate the largest allocation we can as low as we
+ * can. This then becomes the first bank. This bank must be at least
+ * 128MB (or dom0_mem if that is smaller).
+ *
+ * Then we start allocating more memory, trying to allocate the
+ * largest possible size and trying smaller sizes until we
+ * successfully allocate something.
+ *
+ * We then try and insert this memory in to the list of banks. If it
+ * can be merged into an existing bank then this is trivial.
+ *
+ * If the new memory is before the first bank (and cannot be merged
+ * into it) then we give up. Since the allocator prefers to allocate
+ * high addresses first and the first bank has already been allocated
+ * to be as low as possible this likely means we wouldn't have been
+ * able to allocate much more memory anyway.
+ *
+ * Otherwise we insert a new bank. If we've reached MAX_NR_BANKS then
+ * we give up.
+ *
+ * For 32-bit domain we require that the initial allocation for the
+ * first bank is under 4G. Then for the subsequent allocations we
+ * initially allocate memory only from below 4GB. Once that runs out
+ * (as described above) we allow higher allocations and continue until
+ * that runs out (or we have allocated sufficient dom0 memory).
+ */
+static void allocate_memory_11(struct domain *d, struct kernel_info *kinfo)
+{
+ const unsigned int min_low_order =
+ get_order_from_bytes(min_t(paddr_t, dom0_mem, MB(128)));
+ const unsigned int min_order = get_order_from_bytes(MB(4));
+ struct page_info *pg;
+ unsigned int order = get_11_allocation_size(kinfo->unassigned_mem);
+ int i;
+
+ bool_t lowmem = is_32bit_domain(d);
+ unsigned int bits;
+
+ printk("Allocating 1:1 mappings totalling %ldMB for dom0:\n",
+ /* Don't want format this as PRIpaddr (16 digit hex) */
+ (unsigned long)(kinfo->unassigned_mem >> 20));
+
+ kinfo->mem.nr_banks = 0;
+
+ /*
+ * First try and allocate the largest thing we can as low as
+ * possible to be bank 0.
+ */
+ while ( order > min_low_order )
+ {
+ for ( bits = order ; bits < (lowmem ? 32 : PADDR_BITS); bits++ )
+ {
+ pg = alloc_domheap_pages(d, order, MEMF_bits(bits));
+ if ( pg != NULL )
+ goto got_bank0;
+ }
+ order--;
+ }
+
+ panic("Unable to allocate first memory bank");
+
+ got_bank0:
+
+ if ( !insert_11_bank(d, kinfo, pg, order) )
+ BUG(); /* Cannot fail for first bank */
+
+ /* Now allocate more memory and fill in additional banks */
+
+ order = get_11_allocation_size(kinfo->unassigned_mem);
+ while ( kinfo->unassigned_mem && kinfo->mem.nr_banks < NR_MEM_BANKS )
+ {
+ pg = alloc_domheap_pages(d, order, lowmem ? MEMF_bits(32) : 0);
+ if ( !pg )
+ {
+ order --;
+
+ if ( lowmem && order < min_low_order)
+ {
+ D11PRINT("Failed at min_low_order, allow high allocations\n");
+ order = get_11_allocation_size(kinfo->unassigned_mem);
+ lowmem = false;
+ continue;
+ }
+ if ( order >= min_order )
+ continue;
+
+ /* No more we can do */
+ break;
+ }
+
+ if ( !insert_11_bank(d, kinfo, pg, order) )
+ {
+ if ( lowmem )
+ {
+ D11PRINT("Allocation below bank 0, allow high allocations\n");
+ order = get_11_allocation_size(kinfo->unassigned_mem);
+ lowmem = false;
+ continue;
+ }
+ else
+ {
+ D11PRINT("Allocation below bank 0\n");
+ break;
+ }
+ }
+
+ /*
+ * Success, next time around try again to get the largest order
+ * allocation possible.
+ */
+ order = get_11_allocation_size(kinfo->unassigned_mem);
+ }
+
+ if ( kinfo->unassigned_mem )
+ printk("WARNING: Failed to allocate requested dom0 memory."
+ /* Don't want format this as PRIpaddr (16 digit hex) */
+ " %ldMB unallocated\n",
+ (unsigned long)kinfo->unassigned_mem >> 20);
+
+ for( i = 0; i < kinfo->mem.nr_banks; i++ )
+ {
+ printk("BANK[%d] %#"PRIpaddr"-%#"PRIpaddr" (%ldMB)\n",
+ i,
+ kinfo->mem.bank[i].start,
+ kinfo->mem.bank[i].start + kinfo->mem.bank[i].size,
+ /* Don't want format this as PRIpaddr (16 digit hex) */
+ (unsigned long)(kinfo->mem.bank[i].size >> 20));
+ }
}
static void allocate_memory(struct domain *d, struct kernel_info *kinfo)
--
1.7.10.4
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