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Commit 406a590b authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: prepare to make SWITCHER_ADDR a variable. 



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: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 74ff582c

arch/x86/include/asm/lguest.h

+2 −0
Original line number Diff line number Diff line
@@ -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[];

drivers/lguest/core.c

+10 −8
Original line number Diff line number Diff line
@@ -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.

drivers/lguest/x86/core.c

+2 −2
Original line number Diff line number Diff line
@@ -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);