forked from Minki/linux
e5992f2e6c
Add code that allows KVM to control the virtual memory layout that is seen by a guest. The guest address space uses a second page table that shares the last level pte-tables with the process page table. If a page is unmapped from the process page table it is automatically unmapped from the guest page table as well. The guest address space mapping starts out empty, KVM can map any individual 1MB segments from the process virtual memory to any 1MB aligned location in the guest virtual memory. If a target segment in the process virtual memory does not exist or is unmapped while a guest mapping exists the desired target address is stored as an invalid segment table entry in the guest page table. The population of the guest page table is fault driven. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
383 lines
8.4 KiB
C
383 lines
8.4 KiB
C
/*
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* arch/s390/mm/vmem.c
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*
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* Copyright IBM Corp. 2006
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* Author(s): Heiko Carstens <heiko.carstens@de.ibm.com>
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*/
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#include <linux/bootmem.h>
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#include <linux/pfn.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/list.h>
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#include <linux/hugetlb.h>
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#include <linux/slab.h>
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#include <asm/pgalloc.h>
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#include <asm/pgtable.h>
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#include <asm/setup.h>
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#include <asm/tlbflush.h>
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#include <asm/sections.h>
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static DEFINE_MUTEX(vmem_mutex);
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struct memory_segment {
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struct list_head list;
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unsigned long start;
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unsigned long size;
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};
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static LIST_HEAD(mem_segs);
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static void __ref *vmem_alloc_pages(unsigned int order)
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{
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if (slab_is_available())
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return (void *)__get_free_pages(GFP_KERNEL, order);
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return alloc_bootmem_pages((1 << order) * PAGE_SIZE);
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}
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static inline pud_t *vmem_pud_alloc(void)
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{
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pud_t *pud = NULL;
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#ifdef CONFIG_64BIT
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pud = vmem_alloc_pages(2);
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if (!pud)
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return NULL;
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clear_table((unsigned long *) pud, _REGION3_ENTRY_EMPTY, PAGE_SIZE * 4);
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#endif
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return pud;
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}
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static inline pmd_t *vmem_pmd_alloc(void)
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{
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pmd_t *pmd = NULL;
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#ifdef CONFIG_64BIT
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pmd = vmem_alloc_pages(2);
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if (!pmd)
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return NULL;
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clear_table((unsigned long *) pmd, _SEGMENT_ENTRY_EMPTY, PAGE_SIZE * 4);
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#endif
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return pmd;
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}
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static pte_t __ref *vmem_pte_alloc(unsigned long address)
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{
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pte_t *pte;
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if (slab_is_available())
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pte = (pte_t *) page_table_alloc(&init_mm, address);
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else
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pte = alloc_bootmem(PTRS_PER_PTE * sizeof(pte_t));
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if (!pte)
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return NULL;
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clear_table((unsigned long *) pte, _PAGE_TYPE_EMPTY,
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PTRS_PER_PTE * sizeof(pte_t));
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return pte;
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}
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/*
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* Add a physical memory range to the 1:1 mapping.
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*/
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static int vmem_add_mem(unsigned long start, unsigned long size, int ro)
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{
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unsigned long address;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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pte_t pte;
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int ret = -ENOMEM;
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for (address = start; address < start + size; address += PAGE_SIZE) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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pu_dir = vmem_pud_alloc();
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if (!pu_dir)
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goto out;
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pgd_populate(&init_mm, pg_dir, pu_dir);
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}
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pu_dir = pud_offset(pg_dir, address);
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if (pud_none(*pu_dir)) {
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pm_dir = vmem_pmd_alloc();
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if (!pm_dir)
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goto out;
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pud_populate(&init_mm, pu_dir, pm_dir);
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}
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pte = mk_pte_phys(address, __pgprot(ro ? _PAGE_RO : 0));
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pm_dir = pmd_offset(pu_dir, address);
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#ifdef __s390x__
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if (MACHINE_HAS_HPAGE && !(address & ~HPAGE_MASK) &&
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(address + HPAGE_SIZE <= start + size) &&
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(address >= HPAGE_SIZE)) {
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pte_val(pte) |= _SEGMENT_ENTRY_LARGE;
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pmd_val(*pm_dir) = pte_val(pte);
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address += HPAGE_SIZE - PAGE_SIZE;
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continue;
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}
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#endif
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if (pmd_none(*pm_dir)) {
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pt_dir = vmem_pte_alloc(address);
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if (!pt_dir)
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goto out;
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pmd_populate(&init_mm, pm_dir, pt_dir);
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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*pt_dir = pte;
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}
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ret = 0;
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out:
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flush_tlb_kernel_range(start, start + size);
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return ret;
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}
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/*
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* Remove a physical memory range from the 1:1 mapping.
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* Currently only invalidates page table entries.
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*/
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static void vmem_remove_range(unsigned long start, unsigned long size)
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{
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unsigned long address;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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pte_t pte;
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pte_val(pte) = _PAGE_TYPE_EMPTY;
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for (address = start; address < start + size; address += PAGE_SIZE) {
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pg_dir = pgd_offset_k(address);
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pu_dir = pud_offset(pg_dir, address);
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if (pud_none(*pu_dir))
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continue;
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pm_dir = pmd_offset(pu_dir, address);
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if (pmd_none(*pm_dir))
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continue;
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if (pmd_huge(*pm_dir)) {
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pmd_clear(pm_dir);
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address += HPAGE_SIZE - PAGE_SIZE;
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continue;
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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*pt_dir = pte;
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}
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flush_tlb_kernel_range(start, start + size);
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}
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/*
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* Add a backed mem_map array to the virtual mem_map array.
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*/
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int __meminit vmemmap_populate(struct page *start, unsigned long nr, int node)
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{
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unsigned long address, start_addr, end_addr;
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pgd_t *pg_dir;
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pud_t *pu_dir;
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pmd_t *pm_dir;
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pte_t *pt_dir;
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pte_t pte;
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int ret = -ENOMEM;
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start_addr = (unsigned long) start;
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end_addr = (unsigned long) (start + nr);
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for (address = start_addr; address < end_addr; address += PAGE_SIZE) {
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pg_dir = pgd_offset_k(address);
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if (pgd_none(*pg_dir)) {
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pu_dir = vmem_pud_alloc();
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if (!pu_dir)
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goto out;
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pgd_populate(&init_mm, pg_dir, pu_dir);
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}
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pu_dir = pud_offset(pg_dir, address);
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if (pud_none(*pu_dir)) {
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pm_dir = vmem_pmd_alloc();
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if (!pm_dir)
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goto out;
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pud_populate(&init_mm, pu_dir, pm_dir);
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}
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pm_dir = pmd_offset(pu_dir, address);
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if (pmd_none(*pm_dir)) {
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pt_dir = vmem_pte_alloc(address);
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if (!pt_dir)
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goto out;
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pmd_populate(&init_mm, pm_dir, pt_dir);
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}
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pt_dir = pte_offset_kernel(pm_dir, address);
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if (pte_none(*pt_dir)) {
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unsigned long new_page;
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new_page =__pa(vmem_alloc_pages(0));
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if (!new_page)
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goto out;
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pte = pfn_pte(new_page >> PAGE_SHIFT, PAGE_KERNEL);
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*pt_dir = pte;
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}
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}
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memset(start, 0, nr * sizeof(struct page));
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ret = 0;
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out:
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flush_tlb_kernel_range(start_addr, end_addr);
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return ret;
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}
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/*
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* Add memory segment to the segment list if it doesn't overlap with
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* an already present segment.
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*/
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static int insert_memory_segment(struct memory_segment *seg)
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{
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struct memory_segment *tmp;
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if (seg->start + seg->size > VMEM_MAX_PHYS ||
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seg->start + seg->size < seg->start)
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return -ERANGE;
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list_for_each_entry(tmp, &mem_segs, list) {
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if (seg->start >= tmp->start + tmp->size)
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continue;
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if (seg->start + seg->size <= tmp->start)
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continue;
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return -ENOSPC;
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}
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list_add(&seg->list, &mem_segs);
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return 0;
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}
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/*
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* Remove memory segment from the segment list.
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*/
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static void remove_memory_segment(struct memory_segment *seg)
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{
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list_del(&seg->list);
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}
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static void __remove_shared_memory(struct memory_segment *seg)
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{
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remove_memory_segment(seg);
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vmem_remove_range(seg->start, seg->size);
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}
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int vmem_remove_mapping(unsigned long start, unsigned long size)
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{
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struct memory_segment *seg;
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int ret;
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mutex_lock(&vmem_mutex);
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ret = -ENOENT;
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list_for_each_entry(seg, &mem_segs, list) {
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if (seg->start == start && seg->size == size)
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break;
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}
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if (seg->start != start || seg->size != size)
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goto out;
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ret = 0;
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__remove_shared_memory(seg);
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kfree(seg);
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out:
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mutex_unlock(&vmem_mutex);
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return ret;
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}
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int vmem_add_mapping(unsigned long start, unsigned long size)
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{
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struct memory_segment *seg;
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int ret;
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mutex_lock(&vmem_mutex);
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ret = -ENOMEM;
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seg = kzalloc(sizeof(*seg), GFP_KERNEL);
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if (!seg)
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goto out;
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seg->start = start;
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seg->size = size;
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ret = insert_memory_segment(seg);
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if (ret)
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goto out_free;
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ret = vmem_add_mem(start, size, 0);
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if (ret)
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goto out_remove;
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goto out;
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out_remove:
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__remove_shared_memory(seg);
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out_free:
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kfree(seg);
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out:
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mutex_unlock(&vmem_mutex);
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return ret;
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}
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/*
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* map whole physical memory to virtual memory (identity mapping)
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* we reserve enough space in the vmalloc area for vmemmap to hotplug
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* additional memory segments.
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*/
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void __init vmem_map_init(void)
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{
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unsigned long ro_start, ro_end;
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unsigned long start, end;
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int i;
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ro_start = ((unsigned long)&_stext) & PAGE_MASK;
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ro_end = PFN_ALIGN((unsigned long)&_eshared);
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for (i = 0; i < MEMORY_CHUNKS && memory_chunk[i].size > 0; i++) {
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start = memory_chunk[i].addr;
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end = memory_chunk[i].addr + memory_chunk[i].size;
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if (start >= ro_end || end <= ro_start)
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vmem_add_mem(start, end - start, 0);
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else if (start >= ro_start && end <= ro_end)
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vmem_add_mem(start, end - start, 1);
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else if (start >= ro_start) {
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vmem_add_mem(start, ro_end - start, 1);
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vmem_add_mem(ro_end, end - ro_end, 0);
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} else if (end < ro_end) {
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vmem_add_mem(start, ro_start - start, 0);
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vmem_add_mem(ro_start, end - ro_start, 1);
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} else {
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vmem_add_mem(start, ro_start - start, 0);
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vmem_add_mem(ro_start, ro_end - ro_start, 1);
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vmem_add_mem(ro_end, end - ro_end, 0);
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}
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}
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}
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/*
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* Convert memory chunk array to a memory segment list so there is a single
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* list that contains both r/w memory and shared memory segments.
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*/
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static int __init vmem_convert_memory_chunk(void)
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{
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struct memory_segment *seg;
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int i;
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mutex_lock(&vmem_mutex);
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for (i = 0; i < MEMORY_CHUNKS; i++) {
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if (!memory_chunk[i].size)
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continue;
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seg = kzalloc(sizeof(*seg), GFP_KERNEL);
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if (!seg)
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panic("Out of memory...\n");
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seg->start = memory_chunk[i].addr;
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seg->size = memory_chunk[i].size;
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insert_memory_segment(seg);
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}
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mutex_unlock(&vmem_mutex);
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return 0;
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}
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core_initcall(vmem_convert_memory_chunk);
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