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Commit 93a2cdff authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: assume Switcher text is a single page. 



ie. SHARED_SWITCHER_PAGES == 1.  It is well under a page, and it's a
minor simplification: it's nice to have *one* simplification in a
patch series!

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent 856c6088

arch/x86/include/asm/lguest.h

+2 −5
Original line number Diff line number Diff line
@@ -11,11 +11,8 @@ 


#define GUEST_PL 1



/* Every guest maps the core switcher code. */

#define SHARED_SWITCHER_PAGES \

	DIV_ROUND_UP(end_switcher_text - start_switcher_text, PAGE_SIZE)

/* Pages for switcher itself, then two pages per cpu */

#define TOTAL_SWITCHER_PAGES (SHARED_SWITCHER_PAGES + 2 * nr_cpu_ids)

/* Page for Switcher text itself, then two pages per cpu */

#define TOTAL_SWITCHER_PAGES (1 + 2 * nr_cpu_ids)



/* We map at -4M (-2M for PAE) for ease of mapping (one PTE page). */

#ifdef CONFIG_X86_PAE

drivers/lguest/core.c

+8 −1
Original line number Diff line number Diff line
@@ -52,6 +52,13 @@ static __init int map_switcher(void) 
	 * easy.

	 */



	/* We assume Switcher text fits into a single page. */

	if (end_switcher_text - start_switcher_text > PAGE_SIZE) {

		printk(KERN_ERR "lguest: switcher text too large (%zu)\n",

		       end_switcher_text - start_switcher_text);

		return -EINVAL;

	}



	/*

	 * We allocate an array of struct page pointers.  map_vm_area() wants

	 * this, rather than just an array of pages.
@@ -326,7 +333,7 @@ static int __init init(void) 
		goto out;



	/* Now we set up the pagetable implementation for the Guests. */

	err = init_pagetables(switcher_pages, SHARED_SWITCHER_PAGES);

	err = init_pagetables(switcher_pages);

	if (err)

		goto unmap;

drivers/lguest/lg.h

+1 −1
Original line number Diff line number Diff line
@@ -15,7 +15,7 @@ 
#include <asm/lguest.h>



void free_pagetables(void);

int init_pagetables(struct page **switcher_pages, unsigned int pages);

int init_pagetables(struct page **switcher_pages);



struct pgdir {

	unsigned long gpgdir;

drivers/lguest/page_tables.c

+8 −13
Original line number Diff line number Diff line
@@ -1079,25 +1079,20 @@ static void free_switcher_pte_pages(void) 


/*H:520

 * Setting up the Switcher PTE page for given CPU is fairly easy, given

 * the CPU number and the "struct page"s for the Switcher code itself.

 *

 * Currently the Switcher is less than a page long, so "pages" is always 1.

 * the CPU number and the "struct page"s for the Switcher and per-cpu pages.

 */

static __init void populate_switcher_pte_page(unsigned int cpu,

					      struct page *switcher_pages[],

					      unsigned int pages)

					      struct page *switcher_pages[])

{

	unsigned int i;

	pte_t *pte = switcher_pte_page(cpu);

	int i;



	/* The first entries are easy: they map the Switcher code. */

	for (i = 0; i < pages; i++) {

		set_pte(&pte[i], mk_pte(switcher_pages[i],

	/* The first entries maps the Switcher code. */

	set_pte(&pte[0], mk_pte(switcher_pages[0],

				__pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));

	}



	/* The only other thing we map is this CPU's pair of pages. */

	i = pages + cpu*2;

	i = 1 + cpu*2;



	/* First page (Guest registers) is writable from the Guest */

	set_pte(&pte[i], pfn_pte(page_to_pfn(switcher_pages[i]),
@@ -1128,7 +1123,7 @@ static __init void populate_switcher_pte_page(unsigned int cpu, 
 * At boot or module load time, init_pagetables() allocates and populates

 * the Switcher PTE page for each CPU.

 */

__init int init_pagetables(struct page **switcher_pages, unsigned int pages)

__init int init_pagetables(struct page **switcher_pages)

{

	unsigned int i;
@@ -1138,7 +1133,7 @@ __init int init_pagetables(struct page **switcher_pages, unsigned int pages) 
			free_switcher_pte_pages();

			return -ENOMEM;

		}

		populate_switcher_pte_page(i, switcher_pages, pages);

		populate_switcher_pte_page(i, switcher_pages);

	}

	return 0;

}

drivers/lguest/x86/core.c

+2 −3
Original line number Diff line number Diff line
@@ -62,11 +62,10 @@ static unsigned long switcher_offset(void) 
	return switcher_addr - (unsigned long)start_switcher_text;

}



/* This cpu's struct lguest_pages. */

/* This cpu's struct lguest_pages (after the Switcher text page) */

static struct lguest_pages *lguest_pages(unsigned int cpu)

{

	return &(((struct lguest_pages *)

		  (switcher_addr + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);

	return &(((struct lguest_pages *)(switcher_addr + PAGE_SIZE))[cpu]);

}



static DEFINE_PER_CPU(struct lg_cpu *, lg_last_cpu);