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Commit 7f914062 authored by Konrad Rzeszutek Wilk's avatar Konrad Rzeszutek Wilk
Browse files

xen/mmu: Copy and revector the P2M tree. 



Please first read the description in "xen/p2m: Add logic to revector a
P2M tree to use __va leafs" patch.

The 'xen_revector_p2m_tree()' function allocates a new P2M tree
copies the contents of the old one in it, and returns the new one.

At this stage, the __ka address space (which is what the old
P2M tree was using) is partially disassembled. The cleanup_highmap
has removed the PMD entries from 0-16MB and anything past _brk_end
up to the max_pfn_mapped (which is the end of the ramdisk).

We have revectored the P2M tree (and the one for save/restore as well)
to use new shiny __va address to new MFNs. The xen_start_info
has been taken care of already in 'xen_setup_kernel_pagetable()' and
xen_start_info->shared_info in 'xen_setup_shared_info()', so
we are free to roam and delete PMD entries - which is exactly what
we are going to do. We rip out the __ka for the old P2M array.

[v1: Fix smatch warnings]
[v2: memset was doing 0 instead of 0xff]
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
parent 357a3cfb

arch/x86/xen/mmu.c

+57 −0
Original line number Diff line number Diff line
@@ -1183,9 +1183,64 @@ static __init void xen_mapping_pagetable_reserve(u64 start, u64 end) 


static void xen_post_allocator_init(void);



#ifdef CONFIG_X86_64

static void __init xen_cleanhighmap(unsigned long vaddr,

				    unsigned long vaddr_end)

{

	unsigned long kernel_end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;

	pmd_t *pmd = level2_kernel_pgt + pmd_index(vaddr);



	/* NOTE: The loop is more greedy than the cleanup_highmap variant.

	 * We include the PMD passed in on _both_ boundaries. */

	for (; vaddr <= vaddr_end && (pmd < (level2_kernel_pgt + PAGE_SIZE));

			pmd++, vaddr += PMD_SIZE) {

		if (pmd_none(*pmd))

			continue;

		if (vaddr < (unsigned long) _text || vaddr > kernel_end)

			set_pmd(pmd, __pmd(0));

	}

	/* In case we did something silly, we should crash in this function

	 * instead of somewhere later and be confusing. */

	xen_mc_flush();

}

#endif

static void __init xen_pagetable_setup_done(pgd_t *base)

{

#ifdef CONFIG_X86_64

	unsigned long size;

	unsigned long addr;

#endif



	xen_setup_shared_info();

#ifdef CONFIG_X86_64

	if (!xen_feature(XENFEAT_auto_translated_physmap)) {

		unsigned long new_mfn_list;



		size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));



		/* On 32-bit, we get zero so this never gets executed. */

		new_mfn_list = xen_revector_p2m_tree();

		if (new_mfn_list && new_mfn_list != xen_start_info->mfn_list) {

			/* using __ka address and sticking INVALID_P2M_ENTRY! */

			memset((void *)xen_start_info->mfn_list, 0xff, size);



			/* We should be in __ka space. */

			BUG_ON(xen_start_info->mfn_list < __START_KERNEL_map);

			addr = xen_start_info->mfn_list;

			size = PAGE_ALIGN(xen_start_info->nr_pages * sizeof(unsigned long));

			/* We roundup to the PMD, which means that if anybody at this stage is

			 * using the __ka address of xen_start_info or xen_start_info->shared_info

			 * they are in going to crash. Fortunatly we have already revectored

			 * in xen_setup_kernel_pagetable and in xen_setup_shared_info. */

			size = roundup(size, PMD_SIZE);

			xen_cleanhighmap(addr, addr + size);



			memblock_free(__pa(xen_start_info->mfn_list), size);

			/* And revector! Bye bye old array */

			xen_start_info->mfn_list = new_mfn_list;

		}

	}

#endif

	xen_post_allocator_init();

}
@@ -1824,6 +1879,8 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn) 


	/* Our (by three pages) smaller Xen pagetable that we are using */

	memblock_reserve(PFN_PHYS(pt_base), (pt_end - pt_base) * PAGE_SIZE);

	/* Revector the xen_start_info */

	xen_start_info = (struct start_info *)__va(__pa(xen_start_info));

}

#else	/* !CONFIG_X86_64 */

static RESERVE_BRK_ARRAY(pmd_t, initial_kernel_pmd, PTRS_PER_PMD);