[mini-os master] mini-os: don't assume contiguous RAM when initializing in PVH mode

[patchbot@xxxxxxx]

commit e754e3fae198480789fe6d949087e6580f4f614b
Author:     Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Tue Dec 21 09:46:29 2021 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Dec 21 10:53:49 2021 +0000

    mini-os: don't assume contiguous RAM when initializing in PVH mode
    
    Sizing the available memory should respect memory holes, so look at
    the memory map when setting the boundary for the memory allocator.
    
    Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
    Reviewed-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>
---
 arch/x86/mm.c  |  6 +-----
 e820.c         | 14 ++++++++------
 include/e820.h |  2 +-
 3 files changed, 10 insertions(+), 12 deletions(-)

diff --git a/arch/x86/mm.c b/arch/x86/mm.c
index 8df93da..3bf6170 100644
--- a/arch/x86/mm.c
+++ b/arch/x86/mm.c
@@ -107,7 +107,6 @@ void arch_mm_preinit(void *p)
 {
     long ret;
     domid_t domid = DOMID_SELF;
-    unsigned long max;
 
     pt_base = page_table_base;
     first_free_pfn = PFN_UP(to_phys(&_end));
@@ -117,11 +116,8 @@ void arch_mm_preinit(void *p)
         xprintk("could not get memory size\n");
         do_exit();
     }
-    last_free_pfn = ret;
 
-    max = e820_get_maxpfn();
-    if ( max < last_free_pfn )
-        last_free_pfn = max;
+    last_free_pfn = e820_get_maxpfn(ret);
 }
 #endif
 
diff --git a/e820.c b/e820.c
index 70286cb..4c726d1 100644
--- a/e820.c
+++ b/e820.c
@@ -285,10 +285,10 @@ void arch_print_memmap(void)
 }
 #endif
 
-unsigned long e820_get_maxpfn(void)
+unsigned long e820_get_maxpfn(unsigned long pages)
 {
     int i;
-    unsigned long pfn, max = 0;
+    unsigned long pfns = 0, start = 0;
 
     e820_get_memmap();
 
@@ -296,10 +296,12 @@ unsigned long e820_get_maxpfn(void)
     {
         if ( e820_map[i].type != E820_RAM )
             continue;
-        pfn = (e820_map[i].addr + e820_map[i].size) >> PAGE_SHIFT;
-        if ( pfn > max )
-            max = pfn;
+        pfns = e820_map[i].size >> PAGE_SHIFT;
+        start = e820_map[i].addr >> PAGE_SHIFT;
+        if ( pages <= pfns )
+            return start + pages;
+        pages -= pfns;
     }
 
-    return max;
+    return start + pfns;
 }
diff --git a/include/e820.h b/include/e820.h
index af2129f..6a57f05 100644
--- a/include/e820.h
+++ b/include/e820.h
@@ -49,6 +49,6 @@ struct __packed e820entry {
 extern struct e820entry e820_map[];
 extern unsigned e820_entries;
 
-unsigned long e820_get_maxpfn(void);
+unsigned long e820_get_maxpfn(unsigned long pages);
 
 #endif /*__E820_HEADER*/
--
generated by git-patchbot for /home/xen/git/mini-os.git#master