[Xen-devel] [PATCH] tools/hvmloader: move shared_info to reserved memory area

[Olaf Hering <olaf@xxxxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1351101387 -7200
# Node ID 6a0c73ae9ce5cca72f788c0e0f8fd6872010d83e
# Parent  22e08c9ac770db07c3c3e7c844aa7153050939f3
tools/hvmloader: move shared_info to reserved memory area

Reserve a range of 1MB for the HVM shared info page at 0xFE700000. This
area is already marked as reserved in the E820 map. The purpose of this
change is to provide Linux PVonHVM guests with a fixed page outside of
ordinary RAM. If the shared page is located in RAM it would be
overwritten during a kexec boot.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

diff -r 22e08c9ac770 -r 6a0c73ae9ce5 tools/firmware/hvmloader/config.h
--- a/tools/firmware/hvmloader/config.h
+++ b/tools/firmware/hvmloader/config.h
@@ -68,6 +68,8 @@ extern unsigned long pci_mem_start, pci_
 /* NB. ACPI_INFO_PHYSICAL_ADDRESS *MUST* match definition in acpi/dsdt.asl! */
 #define ACPI_INFO_PHYSICAL_ADDRESS    0xFC000000
 #define RESERVED_MEMORY_DYNAMIC       0xFC001000
+#define HVM_SHARED_INFO_AREA          0xFE700000
+#define HVM_SHARED_INFO_SIZE          0x00100000
 
 extern unsigned long scratch_start;
 
diff -r 22e08c9ac770 -r 6a0c73ae9ce5 tools/firmware/hvmloader/util.c
--- a/tools/firmware/hvmloader/util.c
+++ b/tools/firmware/hvmloader/util.c
@@ -433,11 +433,18 @@ void *mem_alloc(uint32_t size, uint32_t 
     if ( align < 16 )
         align = 16;
 
+retry:
     s = (reserve + align) & ~(align - 1);
     e = s + size - 1;
 
     BUG_ON((e < s) || (e >> PAGE_SHIFT) >= hvm_info->reserved_mem_pgstart);
 
+    /* Skip the shared info region */
+    if (s <= HVM_SHARED_INFO_AREA && e >= HVM_SHARED_INFO_AREA) {
+           reserve = HVM_SHARED_INFO_AREA + HVM_SHARED_INFO_SIZE - 1;
+           goto retry;
+    }
+
     while ( (reserve >> PAGE_SHIFT) != (e >> PAGE_SHIFT) )
     {
         reserve += PAGE_SIZE;
@@ -765,7 +772,7 @@ struct shared_info *get_shared_info(void
     xatp.domid = DOMID_SELF;
     xatp.space = XENMAPSPACE_shared_info;
     xatp.idx   = 0;
-    xatp.gpfn  = mem_hole_alloc(1);
+    xatp.gpfn  = HVM_SHARED_INFO_AREA >> PAGE_SHIFT;
     shared_info = (struct shared_info *)(xatp.gpfn << PAGE_SHIFT);
     if ( hypercall_memory_op(XENMEM_add_to_physmap, &xatp) != 0 )
         BUG();

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