Commit 92b4d8df authored by Rusty Russell's avatar Rusty Russell
Browse files

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: default avatarRusty Russell <rusty@rustcorp.com.au>
parent acdd0b62

drivers/lguest/page_tables.c

+21 −17
Original line number Diff line number Diff line
@@ -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,

				pgd_t gpgd, unsigned long vaddr)

			       pmd_t gpmd, unsigned long vaddr)

{

#ifdef CONFIG_X86_PAE

	pmd_t gpmd;

#endif

	unsigned long gpage;

	unsigned long gpage = pmd_pfn(gpmd) << 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));

	return gpage + pte_index(vaddr) * sizeof(pte_t);

}

#else

	gpage = pgd_pfn(gpgd) << PAGE_SHIFT;

#endif

static unsigned long gpte_addr(struct lg_cpu *cpu,

				pgd_t gpgd, unsigned long vaddr)

{

	unsigned long gpage = pgd_pfn(gpgd) << PAGE_SHIFT;



	BUG_ON(!(pgd_flags(gpgd) & _PAGE_PRESENT));

	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));

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