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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] minios: allocate machine contiguous pages
This is a port of XenLinux xen_alloc_contig_memory() to mini-os. A sufficiently privileged mini-os guest can exchange a small number of its pages with machine contiguous pages. Signed-off-by: Rolf Neugebauer <rolf.neugebauer@xxxxxxxxxxxxx> diff -r 3a0165b48266 extras/mini-os/arch/ia64/mm.c
--- a/extras/mini-os/arch/ia64/mm.c Tue Mar 10 18:03:57 2009 +0000
+++ b/extras/mini-os/arch/ia64/mm.c Tue Mar 10 18:10:39 2009 +0000
@@ -162,6 +162,12 @@
ASSERT(0);
}
+unsigned long alloc_contig_pages(int order, unsigned int addr_bits)
+{
+ /* TODO */
+ ASSERT(0);
+}
+
void arch_init_p2m(unsigned long max_pfn)
{
printk("Warn: p2m map not implemented.\n");
diff -r 3a0165b48266 extras/mini-os/arch/x86/mm.c
--- a/extras/mini-os/arch/x86/mm.c Tue Mar 10 18:03:57 2009 +0000
+++ b/extras/mini-os/arch/x86/mm.c Tue Mar 10 18:10:39 2009 +0000
@@ -702,6 +702,148 @@
}
/*
+ * Allocate pages which are contiguous in machine memory.
+ * Returns a VA to where they are mapped or 0 on failure.
+ *
+ * addr_bits indicates if the region has restrictions on where it is
+ * located. Typical values are 32 (if for example PCI devices can't access
+ * 64bit memory) or 0 for no restrictions.
+ *
+ * Allocated pages can be freed using the page allocators free_pages()
+ * function.
+ *
+ * based on Linux function xen_create_contiguous_region()
+ */
+#define MAX_CONTIG_ORDER 9 /* 2MB */
+unsigned long alloc_contig_pages(int order, unsigned int addr_bits)
+{
+ unsigned long in_va, va;
+ unsigned long in_frames[1<<MAX_CONTIG_ORDER], out_frames, mfn;
+ multicall_entry_t call[(1UL << MAX_CONTIG_ORDER)];
+ unsigned int i, num_pages = (1UL << order);
+ int ret, exch_success;
+
+ /* pass in num_pages 'extends' of size 1 and
+ * request 1 extend of size 'order */
+ struct xen_memory_exchange exchange = {
+ .in = {
+ .nr_extents = num_pages,
+ .extent_order = 0,
+ .domid = DOMID_SELF
+ },
+ .out = {
+ .nr_extents = 1,
+ .extent_order = order,
+ .address_bits = addr_bits,
+ .domid = DOMID_SELF
+ },
+ .nr_exchanged = 0
+ };
+
+ if ( order > MAX_CONTIG_ORDER )
+ {
+ printk("alloc_contig_pages: order too large 0x%x > 0x%x\n",
+ order, MAX_CONTIG_ORDER);
+ return 0;
+ }
+
+ /* Allocate some potentially dis-contiguous pages */
+ in_va = alloc_pages(order);
+ if ( !in_va )
+ {
+ printk("alloc_contig_pages: could not get enough pages (order=0x%x\n",
+ order);
+ return 0;
+ }
+
+ /* set up arguments for exchange hyper call */
+ set_xen_guest_handle(exchange.in.extent_start, in_frames);
+ set_xen_guest_handle(exchange.out.extent_start, &out_frames);
+
+ /* unmap current frames, keep a list of MFNs */
+ for ( i = 0; i < num_pages; i++ )
+ {
+ int arg = 0;
+
+ va = in_va + (PAGE_SIZE * i);
+ in_frames[i] = virt_to_mfn(va);
+
+ /* update P2M mapping */
+ phys_to_machine_mapping[virt_to_pfn(va)] = INVALID_P2M_ENTRY;
+
+ /* build multi call */
+ call[i].op = __HYPERVISOR_update_va_mapping;
+ call[i].args[arg++] = va;
+ call[i].args[arg++] = 0;
+#ifdef __i386__
+ call[i].args[arg++] = 0;
+#endif
+ call[i].args[arg++] = UVMF_INVLPG;
+ }
+
+ ret = HYPERVISOR_multicall(call, i);
+ if ( ret )
+ {
+ printk("Odd, update_va_mapping hypercall failed with rc=%d.\n", ret);
+ return 0;
+ }
+
+ /* try getting a contig range of MFNs */
+ out_frames = virt_to_pfn(in_va); /* PFNs to populate */
+ ret = HYPERVISOR_memory_op(XENMEM_exchange, &exchange);
+ if ( ret ) {
+ printk("mem exchanged order=0x%x failed with rc=%d,
nr_exchanged=%d\n",
+ order, ret, exchange.nr_exchanged);
+ /* we still need to return the allocated pages above to the pool
+ * ie. map them back into the 1:1 mapping etc. so we continue but
+ * in the end return the pages to the page allocator and return 0. */
+ exch_success = 0;
+ }
+ else
+ exch_success = 1;
+
+ /* map frames into 1:1 and update p2m */
+ for ( i = 0; i < num_pages; i++ )
+ {
+ int arg = 0;
+ pte_t pte;
+
+ va = in_va + (PAGE_SIZE * i);
+ mfn = i < exchange.nr_exchanged ? (out_frames + i) : in_frames[i];
+ pte = __pte(mfn << PAGE_SHIFT | L1_PROT);
+
+ /* update P2M mapping */
+ phys_to_machine_mapping[virt_to_pfn(va)] = mfn;
+
+ /* build multi call */
+ call[i].op = __HYPERVISOR_update_va_mapping;
+ call[i].args[arg++] = va;
+#ifdef __x86_64__
+ call[i].args[arg++] = (pgentry_t)pte.pte;
+#else
+ call[i].args[arg++] = pte.pte_low;
+ call[i].args[arg++] = pte.pte_high;
+#endif
+ call[i].args[arg++] = UVMF_INVLPG;
+ }
+ ret = HYPERVISOR_multicall(call, i);
+ if ( ret )
+ {
+ printk("update_va_mapping hypercall no. 2 failed with rc=%d.\n", ret);
+ return 0;
+ }
+
+ if ( !exch_success )
+ {
+ /* since the exchanged failed we just free the pages as well */
+ free_pages((void *) in_va, order);
+ return 0;
+ }
+
+ return in_va;
+}
+
+/*
* Check if a given MFN refers to real memory
*/
static long system_ram_end_mfn;
diff -r 3a0165b48266 extras/mini-os/include/mm.h
--- a/extras/mini-os/include/mm.h Tue Mar 10 18:03:57 2009 +0000
+++ b/extras/mini-os/include/mm.h Tue Mar 10 18:10:39 2009 +0000
@@ -72,6 +72,7 @@
unsigned long *f, unsigned long n, unsigned long stride,
unsigned long increment, domid_t id, int may_fail, unsigned long prot);
int unmap_frames(unsigned long va, unsigned long num_frames);
+unsigned long alloc_contig_pages(int order, unsigned int addr_bits);
#ifdef HAVE_LIBC
extern unsigned long heap, brk, heap_mapped, heap_end;
#endif
diff -r 3a0165b48266 extras/mini-os/include/x86/arch_mm.h
--- a/extras/mini-os/include/x86/arch_mm.h Tue Mar 10 18:03:57 2009 +0000
+++ b/extras/mini-os/include/x86/arch_mm.h Tue Mar 10 18:10:39 2009 +0000
@@ -137,6 +137,9 @@
#define IO_PROT (L1_PROT)
#define IO_PROT_NOCACHE (L1_PROT | _PAGE_PCD)
+/* for P2M */
+#define INVALID_P2M_ENTRY (~0UL)
+
#include "arch_limits.h"
#define PAGE_SIZE __PAGE_SIZE
#define PAGE_SHIFT __PAGE_SHIFT
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