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    Subject[PATCH 10/19] xen/dom0: Use host E820 map
    Date
    From: Ian Campbell <ian.campbell@citrix.com>

    Unlike the non-paravirt Xen port we do not have distinct psuedo-physical
    and I/O memory resource-spaces and therefore resources in the two
    can clash. Fix this by registering a memory map which matches the
    underlying I/O map. Currently this wastes the memory in the reserved
    regions. Eventually we should remap this memory to the end of the
    address space.

    Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
    Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    ---
    arch/x86/xen/setup.c | 45 +++++++++++++++++++++++++++++++++++++--
    include/xen/interface/memory.h | 29 +++++++++++++++++++++++++
    2 files changed, 71 insertions(+), 3 deletions(-)
    diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
    index 3e4cf46..175396c 100644
    --- a/arch/x86/xen/setup.c
    +++ b/arch/x86/xen/setup.c
    @@ -19,6 +19,7 @@

    #include <xen/page.h>
    #include <xen/interface/callback.h>
    +#include <xen/interface/memory.h>
    #include <xen/interface/physdev.h>
    #include <xen/features.h>

    @@ -36,16 +37,54 @@ extern void xen_syscall32_target(void);
    /**
    * machine_specific_memory_setup - Hook for machine specific memory setup.
    **/
    -
    char * __init xen_memory_setup(void)
    {
    unsigned long max_pfn = xen_start_info->nr_pages;
    + unsigned long long mem_end;
    + int rc;
    + struct xen_memory_map memmap;
    + /*
    + * This is rather large for a stack variable but this early in
    + * the boot process we know we have plenty slack space.
    + */
    + struct e820entry map[E820MAX];
    + int op = xen_initial_domain() ?
    + XENMEM_machine_memory_map :
    + XENMEM_memory_map;
    + int i;

    max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
    + mem_end = PFN_PHYS((u64)max_pfn);
    +
    + memmap.nr_entries = E820MAX;
    + set_xen_guest_handle(memmap.buffer, map);
    +
    + rc = HYPERVISOR_memory_op(op, &memmap);
    + if (rc == -ENOSYS) {
    + memmap.nr_entries = 1;
    + map[0].addr = 0ULL;
    + map[0].size = mem_end;
    + /* 8MB slack (to balance backend allocations). */
    + map[0].size += 8ULL << 20;
    + map[0].type = E820_RAM;
    + rc = 0;
    + }
    + BUG_ON(rc);

    e820.nr_map = 0;
    -
    - e820_add_region(0, PFN_PHYS((u64)max_pfn), E820_RAM);
    + for (i = 0; i < memmap.nr_entries; i++) {
    + unsigned long long end = map[i].addr + map[i].size;
    + if (map[i].type == E820_RAM) {
    + if (map[i].addr > mem_end)
    + continue;
    + if (end > mem_end) {
    + /* Truncate region to max_mem. */
    + map[i].size -= end - mem_end;
    + }
    + }
    + if (map[i].size > 0)
    + e820_add_region(map[i].addr, map[i].size, map[i].type);
    + }

    /*
    * Even though this is normal, usable memory under Xen, reserve
    diff --git a/include/xen/interface/memory.h b/include/xen/interface/memory.h
    index af36ead..e6c6bcb 100644
    --- a/include/xen/interface/memory.h
    +++ b/include/xen/interface/memory.h
    @@ -142,4 +142,33 @@ struct xen_translate_gpfn_list {
    };
    DEFINE_GUEST_HANDLE_STRUCT(xen_translate_gpfn_list);

    +/*
    + * Returns the pseudo-physical memory map as it was when the domain
    + * was started (specified by XENMEM_set_memory_map).
    + * arg == addr of struct xen_memory_map.
    + */
    +#define XENMEM_memory_map 9
    +struct xen_memory_map {
    + /*
    + * On call the number of entries which can be stored in buffer. On
    + * return the number of entries which have been stored in
    + * buffer.
    + */
    + unsigned int nr_entries;
    +
    + /*
    + * Entries in the buffer are in the same format as returned by the
    + * BIOS INT 0x15 EAX=0xE820 call.
    + */
    + GUEST_HANDLE(void) buffer;
    +};
    +DEFINE_GUEST_HANDLE_STRUCT(xen_memory_map);
    +
    +/*
    + * Returns the real physical memory map. Passes the same structure as
    + * XENMEM_memory_map.
    + * arg == addr of struct xen_memory_map.
    + */
    +#define XENMEM_machine_memory_map 10
    +
    #endif /* __XEN_PUBLIC_MEMORY_H__ */
    --
    1.6.0.6


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