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Date: Sat, 10 Feb 2007 20:33:37 +1100
From: Rusty Russell <rusty@...tcorp.com.au>
To: James Morris <jmorris@...ei.org>
Cc: lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
Andi Kleen <ak@....de>,
Andrew Morton <akpm@...ux-foundation.org>,
virtualization <virtualization@...ts.osdl.org>
Subject: Re: [PATCH 4 of 7] lguest: Config and headers
On Fri, 2007-02-09 at 22:45 -0500, James Morris wrote:
> On Sat, 10 Feb 2007, Rusty Russell wrote:
>
> > Well it was the use of get_order() which triggered Andi's alarm bells,
> > so I went back to deriving it. This code is correct, however.
>
> + hype_pages = alloc_pages(GFP_KERNEL|__GFP_ZERO, HYPERVISOR_MAP_ORDER);
> + if (!hype_pages)
> + return -ENOMEM;
>
> This will try and allocate 2^16 pages. I guess we need a
> HYPERVISOR_PAGE_ORDER ?
Fuck a brick, you're right. Worked here tho 8) There's a moral here
somewhere about futzing with perfectly working code after midnight, I'm
sure.
Name: Don't allocate 2^16 pages in lg.ko
Code cleanup which avoided use of get_order() resulted in a thinko: we
allocated 65536 pages instead of 65536 bytes. Thanks to James Morris
for pointing this out (twice!).
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
diff -r 3bcbcc7c7659 arch/i386/lguest/core.c
--- a/arch/i386/lguest/core.c Sat Feb 10 10:44:25 2007 +1100
+++ b/arch/i386/lguest/core.c Sat Feb 10 20:26:03 2007 +1100
@@ -24,8 +24,8 @@ static char __initdata hypervisor_blob[]
#include "hypervisor-blob.c"
};
-#define MAX_LGUEST_GUESTS \
- (((1 << HYPERVISOR_MAP_ORDER) - sizeof(hypervisor_blob)) \
+#define MAX_LGUEST_GUESTS \
+ (((PAGE_SIZE << HYPERVISOR_PAGE_ORDER) - sizeof(hypervisor_blob)) \
/ sizeof(struct lguest_state))
static struct vm_struct *hypervisor_vma;
@@ -62,12 +62,12 @@ static __init int map_hypervisor(void)
int err;
struct page *pages[HYPERVISOR_PAGES], **pagep = pages;
- hype_pages = alloc_pages(GFP_KERNEL|__GFP_ZERO, HYPERVISOR_MAP_ORDER);
+ hype_pages = alloc_pages(GFP_KERNEL|__GFP_ZERO, HYPERVISOR_PAGE_ORDER);
if (!hype_pages)
return -ENOMEM;
- hypervisor_vma = __get_vm_area(1 << HYPERVISOR_MAP_ORDER, VM_ALLOC,
- HYPE_ADDR, VMALLOC_END);
+ hypervisor_vma = __get_vm_area(PAGE_SIZE << HYPERVISOR_PAGE_ORDER,
+ VM_ALLOC, HYPE_ADDR, VMALLOC_END);
if (!hypervisor_vma) {
err = -ENOMEM;
printk("lguest: could not map hypervisor pages high\n");
@@ -100,14 +100,14 @@ free_vma:
free_vma:
vunmap(hypervisor_vma->addr);
free_pages:
- __free_pages(hype_pages, HYPERVISOR_MAP_ORDER);
+ __free_pages(hype_pages, HYPERVISOR_PAGE_ORDER);
return err;
}
static __exit void unmap_hypervisor(void)
{
vunmap(hypervisor_vma->addr);
- __free_pages(hype_pages, HYPERVISOR_MAP_ORDER);
+ __free_pages(hype_pages, HYPERVISOR_PAGE_ORDER);
}
/* IN/OUT insns: enough to get us past boot-time probing. */
diff -r 3bcbcc7c7659 arch/i386/lguest/lg.h
--- a/arch/i386/lguest/lg.h Sat Feb 10 10:44:25 2007 +1100
+++ b/arch/i386/lguest/lg.h Sat Feb 10 20:27:54 2007 +1100
@@ -3,8 +3,8 @@
#include <asm/desc.h>
/* 64k ought to be enough for anybody! */
-#define HYPERVISOR_MAP_ORDER 16
-#define HYPERVISOR_PAGES ((1 << HYPERVISOR_MAP_ORDER)/PAGE_SIZE)
+#define HYPERVISOR_PAGE_ORDER (16 - PAGE_SHIFT)
+#define HYPERVISOR_PAGES (1 << HYPERVISOR_PAGE_ORDER)
#define GDT_ENTRY_LGUEST_CS 10
#define GDT_ENTRY_LGUEST_DS 11
-
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