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lguest: PAE fixes 

1) j wasn't initialized in setup_pagetables, so they weren't set up for me
   causing immediate guest crashes.

2) gpte_addr should not re-read the pmd from the Guest.  Especially
   not BUG_ON() based on the value.  If we ever supported SMP guests,
   they could trigger that.  And the Launcher could also trigger it
   (tho currently root-only).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2009-06-12 22:27:08 -06:00
parent acdd0b6292
commit 92b4d8df84
1 changed files with 21 additions and 17 deletions
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38
drivers/lguest/page_tables.c
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@ -154,26 +154,25 @@ static unsigned long gpmd_addr(pgd_t gpgd, unsigned long vaddr)
BUG_ON(!(pgd_flags(gpgd) & _PAGE_PRESENT));
return gpage + pmd_index(vaddr) * sizeof(pmd_t);
}
#endif
static unsigned long gpte_addr(struct lg_cpu *cpu,
pmd_t gpmd, unsigned long vaddr)
{
unsigned long gpage = pmd_pfn(gpmd) << PAGE_SHIFT;
BUG_ON(!(pmd_flags(gpmd) & _PAGE_PRESENT));
return gpage + pte_index(vaddr) * sizeof(pte_t);
}
#else
static unsigned long gpte_addr(struct lg_cpu *cpu,
pgd_t gpgd, unsigned long vaddr)
{
#ifdef CONFIG_X86_PAE
pmd_t gpmd;
#endif
unsigned long gpage;
unsigned long gpage = pgd_pfn(gpgd) << PAGE_SHIFT;
BUG_ON(!(pgd_flags(gpgd) & _PAGE_PRESENT));
#ifdef CONFIG_X86_PAE
gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
gpage = pmd_pfn(gpmd) << PAGE_SHIFT;
BUG_ON(!(pmd_flags(gpmd) & _PAGE_PRESENT));
#else
gpage = pgd_pfn(gpgd) << PAGE_SHIFT;
#endif
return gpage + pte_index(vaddr) * sizeof(pte_t);
}
#endif
/*:*/
/*M:014 get_pfn is slow: we could probably try to grab batches of pages here as
@ -339,10 +338,15 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
* number in the shadow PMD is the page we just allocated. */
native_set_pmd(spmd, __pmd(__pa(ptepage) | pmd_flags(gpmd)));
}
#endif
/* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later. */
gpte_ptr = gpte_addr(cpu, gpmd, vaddr);
#else
/* OK, now we look at the lower level in the Guest page table: keep its
* address, because we might update it later. */
gpte_ptr = gpte_addr(cpu, gpgd, vaddr);
#endif
gpte = lgread(cpu, gpte_ptr, pte_t);
/* If this page isn't in the Guest page tables, we can't page it in. */
@ -522,7 +526,6 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
{
pgd_t gpgd;
pte_t gpte;
#ifdef CONFIG_X86_PAE
pmd_t gpmd;
#endif
@ -534,13 +537,14 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr)
return -1UL;
}
gpte = lgread(cpu, gpte_addr(cpu, gpgd, vaddr), pte_t);
#ifdef CONFIG_X86_PAE
gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
kill_guest(cpu, "Bad address %#lx", vaddr);
#endif
gpte = lgread(cpu, gpte_addr(cpu, gpmd, vaddr), pte_t);
#else
gpte = lgread(cpu, gpte_addr(cpu, gpgd, vaddr), pte_t);
#endif
if (!(pte_flags(gpte) & _PAGE_PRESENT))
kill_guest(cpu, "Bad address %#lx", vaddr);
@ -847,7 +851,7 @@ static unsigned long setup_pagetables(struct lguest *lg,
/* The top level points to the linear page table pages above.
* We setup the identity and linear mappings here. */
#ifdef CONFIG_X86_PAE
for (i = 0, j; i < mapped_pages && j < PTRS_PER_PMD;
for (i = j = 0; i < mapped_pages && j < PTRS_PER_PMD;
i += PTRS_PER_PTE, j++) {
native_set_pmd(&pmd, __pmd(((unsigned long)(linear + i)
- mem_base) | _PAGE_PRESENT | _PAGE_RW | _PAGE_USER));