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lguest: map Switcher below fixmap.

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Now we've adjusted all the code, we can simply set switcher_addr to
wherever it needs to go below the fixmaps, rather than asserting that
it should be so.

With large NR_CPUS and PAE, people were hitting the "mapping switcher
would thwack fixmap" message.

Reported-by: Paul Bolle <pebolle@tiscali.nl>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2013-04-22 14:10:42 +09:30
parent 6d0cda93c0
commit 6b39271746
2 changed files with 5 additions and 16 deletions
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6
arch/x86/include/asm/lguest.h
View File

@ -14,12 +14,6 @@
/* 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
#define SWITCHER_ADDR 0xFFE00000
#else
#define SWITCHER_ADDR 0xFFC00000
#endif
/* Where we map the Switcher, in both Host and Guest. */
extern unsigned long switcher_addr;

15
drivers/lguest/core.c
View File

@ -83,18 +83,13 @@ 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.
* We place the Switcher underneath the fixmap area, which is the
* highest virtual address we can get. This is important, since we
* tell the Guest it can't access this memory, so we want its ceiling
* as high as possible.
*/
if (switcher_addr + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
err = -ENOMEM;
printk("lguest: mapping switcher would thwack fixmap\n");
goto free_pages;
}
switcher_addr = FIXADDR_START - (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE;
/*
* Now we reserve the "virtual memory area" we want. We might