diff options
Diffstat (limited to 'arch/i386/xen/mmu.c')
| -rw-r--r-- | arch/i386/xen/mmu.c | 564 |
1 files changed, 0 insertions, 564 deletions
diff --git a/arch/i386/xen/mmu.c b/arch/i386/xen/mmu.c deleted file mode 100644 index 4ae038aa6c24..000000000000 --- a/arch/i386/xen/mmu.c +++ /dev/null @@ -1,564 +0,0 @@ -/* - * Xen mmu operations - * - * This file contains the various mmu fetch and update operations. - * The most important job they must perform is the mapping between the - * domain's pfn and the overall machine mfns. - * - * Xen allows guests to directly update the pagetable, in a controlled - * fashion. In other words, the guest modifies the same pagetable - * that the CPU actually uses, which eliminates the overhead of having - * a separate shadow pagetable. - * - * In order to allow this, it falls on the guest domain to map its - * notion of a "physical" pfn - which is just a domain-local linear - * address - into a real "machine address" which the CPU's MMU can - * use. - * - * A pgd_t/pmd_t/pte_t will typically contain an mfn, and so can be - * inserted directly into the pagetable. When creating a new - * pte/pmd/pgd, it converts the passed pfn into an mfn. Conversely, - * when reading the content back with __(pgd|pmd|pte)_val, it converts - * the mfn back into a pfn. - * - * The other constraint is that all pages which make up a pagetable - * must be mapped read-only in the guest. This prevents uncontrolled - * guest updates to the pagetable. Xen strictly enforces this, and - * will disallow any pagetable update which will end up mapping a - * pagetable page RW, and will disallow using any writable page as a - * pagetable. - * - * Naively, when loading %cr3 with the base of a new pagetable, Xen - * would need to validate the whole pagetable before going on. - * Naturally, this is quite slow. The solution is to "pin" a - * pagetable, which enforces all the constraints on the pagetable even - * when it is not actively in use. This menas that Xen can be assured - * that it is still valid when you do load it into %cr3, and doesn't - * need to revalidate it. - * - * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007 - */ -#include <linux/sched.h> -#include <linux/highmem.h> -#include <linux/bug.h> -#include <linux/sched.h> - -#include <asm/pgtable.h> -#include <asm/tlbflush.h> -#include <asm/mmu_context.h> -#include <asm/paravirt.h> - -#include <asm/xen/hypercall.h> -#include <asm/xen/hypervisor.h> - -#include <xen/page.h> -#include <xen/interface/xen.h> - -#include "multicalls.h" -#include "mmu.h" - -xmaddr_t arbitrary_virt_to_machine(unsigned long address) -{ - pte_t *pte = lookup_address(address); - unsigned offset = address & PAGE_MASK; - - BUG_ON(pte == NULL); - - return XMADDR((pte_mfn(*pte) << PAGE_SHIFT) + offset); -} - -void make_lowmem_page_readonly(void *vaddr) -{ - pte_t *pte, ptev; - unsigned long address = (unsigned long)vaddr; - - pte = lookup_address(address); - BUG_ON(pte == NULL); - - ptev = pte_wrprotect(*pte); - - if (HYPERVISOR_update_va_mapping(address, ptev, 0)) - BUG(); -} - -void make_lowmem_page_readwrite(void *vaddr) -{ - pte_t *pte, ptev; - unsigned long address = (unsigned long)vaddr; - - pte = lookup_address(address); - BUG_ON(pte == NULL); - - ptev = pte_mkwrite(*pte); - - if (HYPERVISOR_update_va_mapping(address, ptev, 0)) - BUG(); -} - - -void xen_set_pmd(pmd_t *ptr, pmd_t val) -{ - struct multicall_space mcs; - struct mmu_update *u; - - preempt_disable(); - - mcs = xen_mc_entry(sizeof(*u)); - u = mcs.args; - u->ptr = virt_to_machine(ptr).maddr; - u->val = pmd_val_ma(val); - MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); - - xen_mc_issue(PARAVIRT_LAZY_MMU); - - preempt_enable(); -} - -/* - * Associate a virtual page frame with a given physical page frame - * and protection flags for that frame. - */ -void set_pte_mfn(unsigned long vaddr, unsigned long mfn, pgprot_t flags) -{ - pgd_t *pgd; - pud_t *pud; - pmd_t *pmd; - pte_t *pte; - - pgd = swapper_pg_dir + pgd_index(vaddr); - if (pgd_none(*pgd)) { - BUG(); - return; - } - pud = pud_offset(pgd, vaddr); - if (pud_none(*pud)) { - BUG(); - return; - } - pmd = pmd_offset(pud, vaddr); - if (pmd_none(*pmd)) { - BUG(); - return; - } - pte = pte_offset_kernel(pmd, vaddr); - /* <mfn,flags> stored as-is, to permit clearing entries */ - xen_set_pte(pte, mfn_pte(mfn, flags)); - - /* - * It's enough to flush this one mapping. - * (PGE mappings get flushed as well) - */ - __flush_tlb_one(vaddr); -} - -void xen_set_pte_at(struct mm_struct *mm, unsigned long addr, - pte_t *ptep, pte_t pteval) -{ - if (mm == current->mm || mm == &init_mm) { - if (xen_get_lazy_mode() == PARAVIRT_LAZY_MMU) { - struct multicall_space mcs; - mcs = xen_mc_entry(0); - - MULTI_update_va_mapping(mcs.mc, addr, pteval, 0); - xen_mc_issue(PARAVIRT_LAZY_MMU); - return; - } else - if (HYPERVISOR_update_va_mapping(addr, pteval, 0) == 0) - return; - } - xen_set_pte(ptep, pteval); -} - -#ifdef CONFIG_X86_PAE -void xen_set_pud(pud_t *ptr, pud_t val) -{ - struct multicall_space mcs; - struct mmu_update *u; - - preempt_disable(); - - mcs = xen_mc_entry(sizeof(*u)); - u = mcs.args; - u->ptr = virt_to_machine(ptr).maddr; - u->val = pud_val_ma(val); - MULTI_mmu_update(mcs.mc, u, 1, NULL, DOMID_SELF); - - xen_mc_issue(PARAVIRT_LAZY_MMU); - - preempt_enable(); -} - -void xen_set_pte(pte_t *ptep, pte_t pte) -{ - ptep->pte_high = pte.pte_high; - smp_wmb(); - ptep->pte_low = pte.pte_low; -} - -void xen_set_pte_atomic(pte_t *ptep, pte_t pte) -{ - set_64bit((u64 *)ptep, pte_val_ma(pte)); -} - -void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) -{ - ptep->pte_low = 0; - smp_wmb(); /* make sure low gets written first */ - ptep->pte_high = 0; -} - -void xen_pmd_clear(pmd_t *pmdp) -{ - xen_set_pmd(pmdp, __pmd(0)); -} - -unsigned long long xen_pte_val(pte_t pte) -{ - unsigned long long ret = 0; - - if (pte.pte_low) { - ret = ((unsigned long long)pte.pte_high << 32) | pte.pte_low; - ret = machine_to_phys(XMADDR(ret)).paddr | 1; - } - - return ret; -} - -unsigned long long xen_pmd_val(pmd_t pmd) -{ - unsigned long long ret = pmd.pmd; - if (ret) - ret = machine_to_phys(XMADDR(ret)).paddr | 1; - return ret; -} - -unsigned long long xen_pgd_val(pgd_t pgd) -{ - unsigned long long ret = pgd.pgd; - if (ret) - ret = machine_to_phys(XMADDR(ret)).paddr | 1; - return ret; -} - -pte_t xen_make_pte(unsigned long long pte) -{ - if (pte & 1) - pte = phys_to_machine(XPADDR(pte)).maddr; - - return (pte_t){ pte, pte >> 32 }; -} - -pmd_t xen_make_pmd(unsigned long long pmd) -{ - if (pmd & 1) - pmd = phys_to_machine(XPADDR(pmd)).maddr; - - return (pmd_t){ pmd }; -} - -pgd_t xen_make_pgd(unsigned long long pgd) -{ - if (pgd & _PAGE_PRESENT) - pgd = phys_to_machine(XPADDR(pgd)).maddr; - - return (pgd_t){ pgd }; -} -#else /* !PAE */ -void xen_set_pte(pte_t *ptep, pte_t pte) -{ - *ptep = pte; -} - -unsigned long xen_pte_val(pte_t pte) -{ - unsigned long ret = pte.pte_low; - - if (ret & _PAGE_PRESENT) - ret = machine_to_phys(XMADDR(ret)).paddr; - - return ret; -} - -unsigned long xen_pgd_val(pgd_t pgd) -{ - unsigned long ret = pgd.pgd; - if (ret) - ret = machine_to_phys(XMADDR(ret)).paddr | 1; - return ret; -} - -pte_t xen_make_pte(unsigned long pte) -{ - if (pte & _PAGE_PRESENT) - pte = phys_to_machine(XPADDR(pte)).maddr; - - return (pte_t){ pte }; -} - -pgd_t xen_make_pgd(unsigned long pgd) -{ - if (pgd & _PAGE_PRESENT) - pgd = phys_to_machine(XPADDR(pgd)).maddr; - - return (pgd_t){ pgd }; -} -#endif /* CONFIG_X86_PAE */ - - - -/* - (Yet another) pagetable walker. This one is intended for pinning a - pagetable. This means that it walks a pagetable and calls the - callback function on each page it finds making up the page table, - at every level. It walks the entire pagetable, but it only bothers - pinning pte pages which are below pte_limit. In the normal case - this will be TASK_SIZE, but at boot we need to pin up to - FIXADDR_TOP. But the important bit is that we don't pin beyond - there, because then we start getting into Xen's ptes. -*/ -static int pgd_walk(pgd_t *pgd_base, int (*func)(struct page *, unsigned), - unsigned long limit) -{ - pgd_t *pgd = pgd_base; - int flush = 0; - unsigned long addr = 0; - unsigned long pgd_next; - - BUG_ON(limit > FIXADDR_TOP); - - if (xen_feature(XENFEAT_auto_translated_physmap)) - return 0; - - for (; addr != FIXADDR_TOP; pgd++, addr = pgd_next) { - pud_t *pud; - unsigned long pud_limit, pud_next; - - pgd_next = pud_limit = pgd_addr_end(addr, FIXADDR_TOP); - - if (!pgd_val(*pgd)) - continue; - - pud = pud_offset(pgd, 0); - - if (PTRS_PER_PUD > 1) /* not folded */ - flush |= (*func)(virt_to_page(pud), 0); - - for (; addr != pud_limit; pud++, addr = pud_next) { - pmd_t *pmd; - unsigned long pmd_limit; - - pud_next = pud_addr_end(addr, pud_limit); - - if (pud_next < limit) - pmd_limit = pud_next; - else - pmd_limit = limit; - - if (pud_none(*pud)) - continue; - - pmd = pmd_offset(pud, 0); - - if (PTRS_PER_PMD > 1) /* not folded */ - flush |= (*func)(virt_to_page(pmd), 0); - - for (; addr != pmd_limit; pmd++) { - addr += (PAGE_SIZE * PTRS_PER_PTE); - if ((pmd_limit-1) < (addr-1)) { - addr = pmd_limit; - break; - } - - if (pmd_none(*pmd)) - continue; - - flush |= (*func)(pmd_page(*pmd), 0); - } - } - } - - flush |= (*func)(virt_to_page(pgd_base), UVMF_TLB_FLUSH); - - return flush; -} - -static int pin_page(struct page *page, unsigned flags) -{ - unsigned pgfl = test_and_set_bit(PG_pinned, &page->flags); - int flush; - - if (pgfl) - flush = 0; /* already pinned */ - else if (PageHighMem(page)) - /* kmaps need flushing if we found an unpinned - highpage */ - flush = 1; - else { - void *pt = lowmem_page_address(page); - unsigned long pfn = page_to_pfn(page); - struct multicall_space mcs = __xen_mc_entry(0); - - flush = 0; - - MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, - pfn_pte(pfn, PAGE_KERNEL_RO), - flags); - } - - return flush; -} - -/* This is called just after a mm has been created, but it has not - been used yet. We need to make sure that its pagetable is all - read-only, and can be pinned. */ -void xen_pgd_pin(pgd_t *pgd) -{ - struct multicall_space mcs; - struct mmuext_op *op; - - xen_mc_batch(); - - if (pgd_walk(pgd, pin_page, TASK_SIZE)) { - /* re-enable interrupts for kmap_flush_unused */ - xen_mc_issue(0); - kmap_flush_unused(); - xen_mc_batch(); - } - - mcs = __xen_mc_entry(sizeof(*op)); - op = mcs.args; - -#ifdef CONFIG_X86_PAE - op->cmd = MMUEXT_PIN_L3_TABLE; -#else - op->cmd = MMUEXT_PIN_L2_TABLE; -#endif - op->arg1.mfn = pfn_to_mfn(PFN_DOWN(__pa(pgd))); - MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); - - xen_mc_issue(0); -} - -/* The init_mm pagetable is really pinned as soon as its created, but - that's before we have page structures to store the bits. So do all - the book-keeping now. */ -static __init int mark_pinned(struct page *page, unsigned flags) -{ - SetPagePinned(page); - return 0; -} - -void __init xen_mark_init_mm_pinned(void) -{ - pgd_walk(init_mm.pgd, mark_pinned, FIXADDR_TOP); -} - -static int unpin_page(struct page *page, unsigned flags) -{ - unsigned pgfl = test_and_clear_bit(PG_pinned, &page->flags); - - if (pgfl && !PageHighMem(page)) { - void *pt = lowmem_page_address(page); - unsigned long pfn = page_to_pfn(page); - struct multicall_space mcs = __xen_mc_entry(0); - - MULTI_update_va_mapping(mcs.mc, (unsigned long)pt, - pfn_pte(pfn, PAGE_KERNEL), - flags); - } - - return 0; /* never need to flush on unpin */ -} - -/* Release a pagetables pages back as normal RW */ -static void xen_pgd_unpin(pgd_t *pgd) -{ - struct mmuext_op *op; - struct multicall_space mcs; - - xen_mc_batch(); - - mcs = __xen_mc_entry(sizeof(*op)); - - op = mcs.args; - op->cmd = MMUEXT_UNPIN_TABLE; - op->arg1.mfn = pfn_to_mfn(PFN_DOWN(__pa(pgd))); - - MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF); - - pgd_walk(pgd, unpin_page, TASK_SIZE); - - xen_mc_issue(0); -} - -void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next) -{ - spin_lock(&next->page_table_lock); - xen_pgd_pin(next->pgd); - spin_unlock(&next->page_table_lock); -} - -void xen_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) -{ - spin_lock(&mm->page_table_lock); - xen_pgd_pin(mm->pgd); - spin_unlock(&mm->page_table_lock); -} - - -#ifdef CONFIG_SMP -/* Another cpu may still have their %cr3 pointing at the pagetable, so - we need to repoint it somewhere else before we can unpin it. */ -static void drop_other_mm_ref(void *info) -{ - struct mm_struct *mm = info; - - if (__get_cpu_var(cpu_tlbstate).active_mm == mm) - leave_mm(smp_processor_id()); -} - -static void drop_mm_ref(struct mm_struct *mm) -{ - if (current->active_mm == mm) { - if (current->mm == mm) - load_cr3(swapper_pg_dir); - else - leave_mm(smp_processor_id()); - } - - if (!cpus_empty(mm->cpu_vm_mask)) - xen_smp_call_function_mask(mm->cpu_vm_mask, drop_other_mm_ref, - mm, 1); -} -#else -static void drop_mm_ref(struct mm_struct *mm) -{ - if (current->active_mm == mm) - load_cr3(swapper_pg_dir); -} -#endif - -/* - * While a process runs, Xen pins its pagetables, which means that the - * hypervisor forces it to be read-only, and it controls all updates - * to it. This means that all pagetable updates have to go via the - * hypervisor, which is moderately expensive. - * - * Since we're pulling the pagetable down, we switch to use init_mm, - * unpin old process pagetable and mark it all read-write, which - * allows further operations on it to be simple memory accesses. - * - * The only subtle point is that another CPU may be still using the - * pagetable because of lazy tlb flushing. This means we need need to - * switch all CPUs off this pagetable before we can unpin it. - */ -void xen_exit_mmap(struct mm_struct *mm) -{ - get_cpu(); /* make sure we don't move around */ - drop_mm_ref(mm); - put_cpu(); - - spin_lock(&mm->page_table_lock); - xen_pgd_unpin(mm->pgd); - spin_unlock(&mm->page_table_lock); -} |
