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lguest: prepare to make SWITCHER_ADDR a variable.

Browse source 
We currently use the whole top PGD entry for the switcher, but that's
hitting the fixmap in some configurations (mainly, large NR_CPUS).
Introduce a variable, currently set to the constant.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2013-04-22 14:10:37 +09:30
parent 74ff582cd6
commit 406a590ba1
3 changed files with 14 additions and 10 deletions
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2
arch/x86/include/asm/lguest.h
View file

@ -23,6 +23,8 @@
#else
#define SWITCHER_ADDR 0xFFC00000
#endif
/* Where we map the Switcher, in both Host and Guest. */
extern unsigned long switcher_addr;
/* Found in switcher.S */
extern unsigned long default_idt_entries[];

18
drivers/lguest/core.c
View file

@ -20,7 +20,7 @@
#include <asm/asm-offsets.h>
#include "lg.h"
unsigned long switcher_addr;
static struct vm_struct *switcher_vma;
static struct page **switcher_page;
@ -75,25 +75,27 @@ static __init int map_switcher(void)
}
}
switcher_addr = SWITCHER_ADDR;
/*
* First we check that the Switcher won't overlap the fixmap area at
* the top of memory. It's currently nowhere near, but it could have
* very strange effects if it ever happened.
*/
if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
if (switcher_addr + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
err = -ENOMEM;
printk("lguest: mapping switcher would thwack fixmap\n");
goto free_pages;
}
/*
* Now we reserve the "virtual memory area" we want: 0xFFC00000
* (SWITCHER_ADDR). We might not get it in theory, but in practice
* it's worked so far. The end address needs +1 because __get_vm_area
* allocates an extra guard page, so we need space for that.
* Now we reserve the "virtual memory area" we want. We might
* not get it in theory, but in practice it's worked so far.
* The end address needs +1 because __get_vm_area allocates an
* extra guard page, so we need space for that.
*/
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
VM_ALLOC, switcher_addr, switcher_addr
+ (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
if (!switcher_vma) {
err = -ENOMEM;
@ -103,7 +105,7 @@ static __init int map_switcher(void)
/*
* This code actually sets up the pages we've allocated to appear at
* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
* switcher_addr. map_vm_area() takes the vma we allocated above, the
* kind of pages we're mapping (kernel pages), and a pointer to our
* array of struct pages. It increments that pointer, but we don't
* care.

4
drivers/lguest/x86/core.c
View file

@ -59,14 +59,14 @@ static struct {
/* Offset from where switcher.S was compiled to where we've copied it */
static unsigned long switcher_offset(void)
{
return SWITCHER_ADDR - (unsigned long)start_switcher_text;
return switcher_addr - (unsigned long)start_switcher_text;
}
/* This cpu's struct lguest_pages. */
static struct lguest_pages *lguest_pages(unsigned int cpu)
{
return &(((struct lguest_pages *)
(SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
(switcher_addr + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
}
static DEFINE_PER_CPU(struct lg_cpu *, lg_last_cpu);