-/*P:700 The pagetable code, on the other hand, still shows the scars of
+/*P:700
+ * The pagetable code, on the other hand, still shows the scars of
* previous encounters. It's functional, and as neat as it can be in the
* circumstances, but be wary, for these things are subtle and break easily.
* The Guest provides a virtual to physical mapping, but we can neither trust
- * it nor use it: we verify and convert it here to point the hardware to the
- * actual Guest pages when running the Guest. :*/
+ * it nor use it: we verify and convert it here then point the CPU to the
+ * converted Guest pages when running the Guest.
+:*/
/* Copyright (C) Rusty Russell IBM Corporation 2006.
* GPL v2 and any later version */
#include <linux/mm.h>
+#include <linux/gfp.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/random.h>
#include <linux/percpu.h>
#include <asm/tlbflush.h>
#include <asm/uaccess.h>
+#include <asm/bootparam.h>
#include "lg.h"
-/*M:008 We hold reference to pages, which prevents them from being swapped.
+/*M:008
+ * We hold reference to pages, which prevents them from being swapped.
* It'd be nice to have a callback in the "struct mm_struct" when Linux wants
* to swap out. If we had this, and a shrinker callback to trim PTE pages, we
- * could probably consider launching Guests as non-root. :*/
+ * could probably consider launching Guests as non-root.
+:*/
/*H:300
* The Page Table Code
*
- * We use two-level page tables for the Guest. If you're not entirely
- * comfortable with virtual addresses, physical addresses and page tables then
- * I recommend you review arch/x86/lguest/boot.c's "Page Table Handling" (with
- * diagrams!).
+ * We use two-level page tables for the Guest, or three-level with PAE. If
+ * you're not entirely comfortable with virtual addresses, physical addresses
+ * and page tables then I recommend you review arch/x86/lguest/boot.c's "Page
+ * Table Handling" (with diagrams!).
*
* The Guest keeps page tables, but we maintain the actual ones here: these are
* called "shadow" page tables. Which is a very Guest-centric name: these are
* (v) Flushing (throwing away) page tables,
* (vi) Mapping the Switcher when the Guest is about to run,
* (vii) Setting up the page tables initially.
- :*/
+:*/
-
-/* 1024 entries in a page table page maps 1024 pages: 4MB. The Switcher is
- * conveniently placed at the top 4MB, so it uses a separate, complete PTE
- * page. */
+/*
+ * The Switcher uses the complete top PTE page. That's 1024 PTE entries (4MB)
+ * or 512 PTE entries with PAE (2MB).
+ */
#define SWITCHER_PGD_INDEX (PTRS_PER_PGD - 1)
-/* We actually need a separate PTE page for each CPU. Remember that after the
+/*
+ * For PAE we need the PMD index as well. We use the last 2MB, so we
+ * will need the last pmd entry of the last pmd page.
+ */
+#ifdef CONFIG_X86_PAE
+#define SWITCHER_PMD_INDEX (PTRS_PER_PMD - 1)
+#define RESERVE_MEM 2U
+#define CHECK_GPGD_MASK _PAGE_PRESENT
+#else
+#define RESERVE_MEM 4U
+#define CHECK_GPGD_MASK _PAGE_TABLE
+#endif
+
+/*
+ * We actually need a separate PTE page for each CPU. Remember that after the
* Switcher code itself comes two pages for each CPU, and we don't want this
- * CPU's guest to see the pages of any other CPU. */
+ * CPU's guest to see the pages of any other CPU.
+ */
static DEFINE_PER_CPU(pte_t *, switcher_pte_pages);
#define switcher_pte_page(cpu) per_cpu(switcher_pte_pages, cpu)
-/*H:320 The page table code is curly enough to need helper functions to keep it
- * clear and clean.
+/*H:320
+ * The page table code is curly enough to need helper functions to keep it
+ * clear and clean. The kernel itself provides many of them; one advantage
+ * of insisting that the Guest and Host use the same CONFIG_PAE setting.
*
* There are two functions which return pointers to the shadow (aka "real")
* page tables.
* spgd_addr() takes the virtual address and returns a pointer to the top-level
* page directory entry (PGD) for that address. Since we keep track of several
* page tables, the "i" argument tells us which one we're interested in (it's
- * usually the current one). */
-static pgd_t *spgd_addr(struct lguest *lg, u32 i, unsigned long vaddr)
+ * usually the current one).
+ */
+static pgd_t *spgd_addr(struct lg_cpu *cpu, u32 i, unsigned long vaddr)
{
unsigned int index = pgd_index(vaddr);
+#ifndef CONFIG_X86_PAE
/* We kill any Guest trying to touch the Switcher addresses. */
if (index >= SWITCHER_PGD_INDEX) {
- kill_guest(lg, "attempt to access switcher pages");
+ kill_guest(cpu, "attempt to access switcher pages");
index = 0;
}
+#endif
/* Return a pointer index'th pgd entry for the i'th page table. */
- return &lg->pgdirs[i].pgdir[index];
+ return &cpu->lg->pgdirs[i].pgdir[index];
+}
+
+#ifdef CONFIG_X86_PAE
+/*
+ * This routine then takes the PGD entry given above, which contains the
+ * address of the PMD page. It then returns a pointer to the PMD entry for the
+ * given address.
+ */
+static pmd_t *spmd_addr(struct lg_cpu *cpu, pgd_t spgd, unsigned long vaddr)
+{
+ unsigned int index = pmd_index(vaddr);
+ pmd_t *page;
+
+ /* We kill any Guest trying to touch the Switcher addresses. */
+ if (pgd_index(vaddr) == SWITCHER_PGD_INDEX &&
+ index >= SWITCHER_PMD_INDEX) {
+ kill_guest(cpu, "attempt to access switcher pages");
+ index = 0;
+ }
+
+ /* You should never call this if the PGD entry wasn't valid */
+ BUG_ON(!(pgd_flags(spgd) & _PAGE_PRESENT));
+ page = __va(pgd_pfn(spgd) << PAGE_SHIFT);
+
+ return &page[index];
}
+#endif
-/* This routine then takes the page directory entry returned above, which
+/*
+ * This routine then takes the page directory entry returned above, which
* contains the address of the page table entry (PTE) page. It then returns a
- * pointer to the PTE entry for the given address. */
-static pte_t *spte_addr(struct lguest *lg, pgd_t spgd, unsigned long vaddr)
+ * pointer to the PTE entry for the given address.
+ */
+static pte_t *spte_addr(struct lg_cpu *cpu, pgd_t spgd, unsigned long vaddr)
{
+#ifdef CONFIG_X86_PAE
+ pmd_t *pmd = spmd_addr(cpu, spgd, vaddr);
+ pte_t *page = __va(pmd_pfn(*pmd) << PAGE_SHIFT);
+
+ /* You should never call this if the PMD entry wasn't valid */
+ BUG_ON(!(pmd_flags(*pmd) & _PAGE_PRESENT));
+#else
pte_t *page = __va(pgd_pfn(spgd) << PAGE_SHIFT);
/* You should never call this if the PGD entry wasn't valid */
BUG_ON(!(pgd_flags(spgd) & _PAGE_PRESENT));
- return &page[(vaddr >> PAGE_SHIFT) % PTRS_PER_PTE];
+#endif
+
+ return &page[pte_index(vaddr)];
}
-/* These two functions just like the above two, except they access the Guest
- * page tables. Hence they return a Guest address. */
-static unsigned long gpgd_addr(struct lguest *lg, unsigned long vaddr)
+/*
+ * These functions are just like the above two, except they access the Guest
+ * page tables. Hence they return a Guest address.
+ */
+static unsigned long gpgd_addr(struct lg_cpu *cpu, unsigned long vaddr)
{
unsigned int index = vaddr >> (PGDIR_SHIFT);
- return lg->pgdirs[lg->pgdidx].gpgdir + index * sizeof(pgd_t);
+ return cpu->lg->pgdirs[cpu->cpu_pgd].gpgdir + index * sizeof(pgd_t);
+}
+
+#ifdef CONFIG_X86_PAE
+/* Follow the PGD to the PMD. */
+static unsigned long gpmd_addr(pgd_t gpgd, unsigned long vaddr)
+{
+ unsigned long gpage = pgd_pfn(gpgd) << PAGE_SHIFT;
+ BUG_ON(!(pgd_flags(gpgd) & _PAGE_PRESENT));
+ return gpage + pmd_index(vaddr) * sizeof(pmd_t);
}
-static unsigned long gpte_addr(struct lguest *lg,
- pgd_t gpgd, unsigned long vaddr)
+/* Follow the PMD to the PTE. */
+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
+/* Follow the PGD to the PTE (no mid-level for !PAE). */
+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 + ((vaddr>>PAGE_SHIFT) % PTRS_PER_PTE) * sizeof(pte_t);
+ 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
+ * an optimization (ie. pre-faulting).
+:*/
-/*H:350 This routine takes a page number given by the Guest and converts it to
+/*H:350
+ * This routine takes a page number given by the Guest and converts it to
* an actual, physical page number. It can fail for several reasons: the
* virtual address might not be mapped by the Launcher, the write flag is set
* and the page is read-only, or the write flag was set and the page was
* shared so had to be copied, but we ran out of memory.
*
- * This holds a reference to the page, so release_pte() is careful to
- * put that back. */
+ * This holds a reference to the page, so release_pte() is careful to put that
+ * back.
+ */
static unsigned long get_pfn(unsigned long virtpfn, int write)
{
struct page *page;
- /* This value indicates failure. */
- unsigned long ret = -1UL;
- /* get_user_pages() is a complex interface: it gets the "struct
- * vm_area_struct" and "struct page" assocated with a range of pages.
- * It also needs the task's mmap_sem held, and is not very quick.
- * It returns the number of pages it got. */
- down_read(¤t->mm->mmap_sem);
- if (get_user_pages(current, current->mm, virtpfn << PAGE_SHIFT,
- 1, write, 1, &page, NULL) == 1)
- ret = page_to_pfn(page);
- up_read(¤t->mm->mmap_sem);
- return ret;
+ /* gup me one page at this address please! */
+ if (get_user_pages_fast(virtpfn << PAGE_SHIFT, 1, write, &page) == 1)
+ return page_to_pfn(page);
+
+ /* This value indicates failure. */
+ return -1UL;
}
-/*H:340 Converting a Guest page table entry to a shadow (ie. real) page table
+/*H:340
+ * Converting a Guest page table entry to a shadow (ie. real) page table
* entry can be a little tricky. The flags are (almost) the same, but the
* Guest PTE contains a virtual page number: the CPU needs the real page
- * number. */
-static pte_t gpte_to_spte(struct lguest *lg, pte_t gpte, int write)
+ * number.
+ */
+static pte_t gpte_to_spte(struct lg_cpu *cpu, pte_t gpte, int write)
{
unsigned long pfn, base, flags;
- /* The Guest sets the global flag, because it thinks that it is using
+ /*
+ * The Guest sets the global flag, because it thinks that it is using
* PGE. We only told it to use PGE so it would tell us whether it was
* flushing a kernel mapping or a userspace mapping. We don't actually
- * use the global bit, so throw it away. */
+ * use the global bit, so throw it away.
+ */
flags = (pte_flags(gpte) & ~_PAGE_GLOBAL);
/* The Guest's pages are offset inside the Launcher. */
- base = (unsigned long)lg->mem_base / PAGE_SIZE;
+ base = (unsigned long)cpu->lg->mem_base / PAGE_SIZE;
- /* We need a temporary "unsigned long" variable to hold the answer from
+ /*
+ * We need a temporary "unsigned long" variable to hold the answer from
* get_pfn(), because it returns 0xFFFFFFFF on failure, which wouldn't
* fit in spte.pfn. get_pfn() finds the real physical number of the
- * page, given the virtual number. */
+ * page, given the virtual number.
+ */
pfn = get_pfn(base + pte_pfn(gpte), write);
if (pfn == -1UL) {
- kill_guest(lg, "failed to get page %lu", pte_pfn(gpte));
- /* When we destroy the Guest, we'll go through the shadow page
+ kill_guest(cpu, "failed to get page %lu", pte_pfn(gpte));
+ /*
+ * When we destroy the Guest, we'll go through the shadow page
* tables and release_pte() them. Make sure we don't think
- * this one is valid! */
+ * this one is valid!
+ */
flags = 0;
}
/* Now we assemble our shadow PTE from the page number and flags. */
/*H:460 And to complete the chain, release_pte() looks like this: */
static void release_pte(pte_t pte)
{
- /* Remember that get_user_pages() took a reference to the page, in
- * get_pfn()? We have to put it back now. */
+ /*
+ * Remember that get_user_pages_fast() took a reference to the page, in
+ * get_pfn()? We have to put it back now.
+ */
if (pte_flags(pte) & _PAGE_PRESENT)
- put_page(pfn_to_page(pte_pfn(pte)));
+ put_page(pte_page(pte));
}
/*:*/
-static void check_gpte(struct lguest *lg, pte_t gpte)
+static void check_gpte(struct lg_cpu *cpu, pte_t gpte)
+{
+ if ((pte_flags(gpte) & _PAGE_PSE) ||
+ pte_pfn(gpte) >= cpu->lg->pfn_limit)
+ kill_guest(cpu, "bad page table entry");
+}
+
+static void check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
{
- if ((pte_flags(gpte) & (_PAGE_PWT|_PAGE_PSE))
- || pte_pfn(gpte) >= lg->pfn_limit)
- kill_guest(lg, "bad page table entry");
+ if ((pgd_flags(gpgd) & ~CHECK_GPGD_MASK) ||
+ (pgd_pfn(gpgd) >= cpu->lg->pfn_limit))
+ kill_guest(cpu, "bad page directory entry");
}
-static void check_gpgd(struct lguest *lg, pgd_t gpgd)
+#ifdef CONFIG_X86_PAE
+static void check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
{
- if ((pgd_flags(gpgd) & ~_PAGE_TABLE) || pgd_pfn(gpgd) >= lg->pfn_limit)
- kill_guest(lg, "bad page directory entry");
+ if ((pmd_flags(gpmd) & ~_PAGE_TABLE) ||
+ (pmd_pfn(gpmd) >= cpu->lg->pfn_limit))
+ kill_guest(cpu, "bad page middle directory entry");
}
+#endif
/*H:330
* (i) Looking up a page table entry when the Guest faults.
* and return to the Guest without it knowing.
*
* If we fixed up the fault (ie. we mapped the address), this routine returns
- * true. Otherwise, it was a real fault and we need to tell the Guest. */
-int demand_page(struct lguest *lg, unsigned long vaddr, int errcode)
+ * true. Otherwise, it was a real fault and we need to tell the Guest.
+ */
+bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
{
pgd_t gpgd;
pgd_t *spgd;
pte_t gpte;
pte_t *spte;
+ /* Mid level for PAE. */
+#ifdef CONFIG_X86_PAE
+ pmd_t *spmd;
+ pmd_t gpmd;
+#endif
+
/* First step: get the top-level Guest page table entry. */
- gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
+ gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
- return 0;
+ return false;
/* Now look at the matching shadow entry. */
- spgd = spgd_addr(lg, lg->pgdidx, vaddr);
+ spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
if (!(pgd_flags(*spgd) & _PAGE_PRESENT)) {
/* No shadow entry: allocate a new shadow PTE page. */
unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
- /* This is not really the Guest's fault, but killing it is
- * simple for this corner case. */
+ /*
+ * This is not really the Guest's fault, but killing it is
+ * simple for this corner case.
+ */
if (!ptepage) {
- kill_guest(lg, "out of memory allocating pte page");
- return 0;
+ kill_guest(cpu, "out of memory allocating pte page");
+ return false;
}
/* We check that the Guest pgd is OK. */
- check_gpgd(lg, gpgd);
- /* And we copy the flags to the shadow PGD entry. The page
- * number in the shadow PGD is the page we just allocated. */
- *spgd = __pgd(__pa(ptepage) | pgd_flags(gpgd));
+ check_gpgd(cpu, gpgd);
+ /*
+ * And we copy the flags to the shadow PGD entry. The page
+ * number in the shadow PGD is the page we just allocated.
+ */
+ set_pgd(spgd, __pgd(__pa(ptepage) | pgd_flags(gpgd)));
+ }
+
+#ifdef CONFIG_X86_PAE
+ gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t);
+ /* Middle level not present? We can't map it in. */
+ if (!(pmd_flags(gpmd) & _PAGE_PRESENT))
+ return false;
+
+ /* Now look at the matching shadow entry. */
+ spmd = spmd_addr(cpu, *spgd, vaddr);
+
+ if (!(pmd_flags(*spmd) & _PAGE_PRESENT)) {
+ /* No shadow entry: allocate a new shadow PTE page. */
+ unsigned long ptepage = get_zeroed_page(GFP_KERNEL);
+
+ /*
+ * This is not really the Guest's fault, but killing it is
+ * simple for this corner case.
+ */
+ if (!ptepage) {
+ kill_guest(cpu, "out of memory allocating pte page");
+ return false;
+ }
+
+ /* We check that the Guest pmd is OK. */
+ check_gpmd(cpu, gpmd);
+
+ /*
+ * And we copy the flags to the shadow PMD entry. The page
+ * number in the shadow PMD is the page we just allocated.
+ */
+ set_pmd(spmd, __pmd(__pa(ptepage) | pmd_flags(gpmd)));
}
- /* 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(lg, gpgd, vaddr);
- gpte = lgread(lg, gpte_ptr, pte_t);
+ /*
+ * 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
+
+ /* Read the actual PTE value. */
+ gpte = lgread(cpu, gpte_ptr, pte_t);
/* If this page isn't in the Guest page tables, we can't page it in. */
if (!(pte_flags(gpte) & _PAGE_PRESENT))
- return 0;
+ return false;
- /* Check they're not trying to write to a page the Guest wants
- * read-only (bit 2 of errcode == write). */
+ /*
+ * Check they're not trying to write to a page the Guest wants
+ * read-only (bit 2 of errcode == write).
+ */
if ((errcode & 2) && !(pte_flags(gpte) & _PAGE_RW))
- return 0;
+ return false;
/* User access to a kernel-only page? (bit 3 == user access) */
if ((errcode & 4) && !(pte_flags(gpte) & _PAGE_USER))
- return 0;
+ return false;
- /* Check that the Guest PTE flags are OK, and the page number is below
- * the pfn_limit (ie. not mapping the Launcher binary). */
- check_gpte(lg, gpte);
+ /*
+ * Check that the Guest PTE flags are OK, and the page number is below
+ * the pfn_limit (ie. not mapping the Launcher binary).
+ */
+ check_gpte(cpu, gpte);
/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
gpte = pte_mkyoung(gpte);
gpte = pte_mkdirty(gpte);
/* Get the pointer to the shadow PTE entry we're going to set. */
- spte = spte_addr(lg, *spgd, vaddr);
- /* If there was a valid shadow PTE entry here before, we release it.
- * This can happen with a write to a previously read-only entry. */
+ spte = spte_addr(cpu, *spgd, vaddr);
+
+ /*
+ * If there was a valid shadow PTE entry here before, we release it.
+ * This can happen with a write to a previously read-only entry.
+ */
release_pte(*spte);
- /* If this is a write, we insist that the Guest page is writable (the
- * final arg to gpte_to_spte()). */
+ /*
+ * If this is a write, we insist that the Guest page is writable (the
+ * final arg to gpte_to_spte()).
+ */
if (pte_dirty(gpte))
- *spte = gpte_to_spte(lg, gpte, 1);
+ *spte = gpte_to_spte(cpu, gpte, 1);
else
- /* If this is a read, don't set the "writable" bit in the page
+ /*
+ * If this is a read, don't set the "writable" bit in the page
* table entry, even if the Guest says it's writable. That way
* we will come back here when a write does actually occur, so
- * we can update the Guest's _PAGE_DIRTY flag. */
- *spte = gpte_to_spte(lg, pte_wrprotect(gpte), 0);
-
- /* Finally, we write the Guest PTE entry back: we've set the
- * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags. */
- lgwrite(lg, gpte_ptr, pte_t, gpte);
-
- /* The fault is fixed, the page table is populated, the mapping
+ * we can update the Guest's _PAGE_DIRTY flag.
+ */
+ set_pte(spte, gpte_to_spte(cpu, pte_wrprotect(gpte), 0));
+
+ /*
+ * Finally, we write the Guest PTE entry back: we've set the
+ * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags.
+ */
+ lgwrite(cpu, gpte_ptr, pte_t, gpte);
+
+ /*
+ * The fault is fixed, the page table is populated, the mapping
* manipulated, the result returned and the code complete. A small
* delay and a trace of alliteration are the only indications the Guest
- * has that a page fault occurred at all. */
- return 1;
+ * has that a page fault occurred at all.
+ */
+ return true;
}
/*H:360
* mapped, so it's overkill.
*
* This is a quick version which answers the question: is this virtual address
- * mapped by the shadow page tables, and is it writable? */
-static int page_writable(struct lguest *lg, unsigned long vaddr)
+ * mapped by the shadow page tables, and is it writable?
+ */
+static bool page_writable(struct lg_cpu *cpu, unsigned long vaddr)
{
pgd_t *spgd;
unsigned long flags;
+#ifdef CONFIG_X86_PAE
+ pmd_t *spmd;
+#endif
/* Look at the current top level entry: is it present? */
- spgd = spgd_addr(lg, lg->pgdidx, vaddr);
+ spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
if (!(pgd_flags(*spgd) & _PAGE_PRESENT))
- return 0;
+ return false;
- /* Check the flags on the pte entry itself: it must be present and
- * writable. */
- flags = pte_flags(*(spte_addr(lg, *spgd, vaddr)));
+#ifdef CONFIG_X86_PAE
+ spmd = spmd_addr(cpu, *spgd, vaddr);
+ if (!(pmd_flags(*spmd) & _PAGE_PRESENT))
+ return false;
+#endif
+
+ /*
+ * Check the flags on the pte entry itself: it must be present and
+ * writable.
+ */
+ flags = pte_flags(*(spte_addr(cpu, *spgd, vaddr)));
return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
}
-/* So, when pin_stack_pages() asks us to pin a page, we check if it's already
+/*
+ * So, when pin_stack_pages() asks us to pin a page, we check if it's already
* in the page tables, and if not, we call demand_page() with error code 2
- * (meaning "write"). */
-void pin_page(struct lguest *lg, unsigned long vaddr)
+ * (meaning "write").
+ */
+void pin_page(struct lg_cpu *cpu, unsigned long vaddr)
{
- if (!page_writable(lg, vaddr) && !demand_page(lg, vaddr, 2))
- kill_guest(lg, "bad stack page %#lx", vaddr);
+ if (!page_writable(cpu, vaddr) && !demand_page(cpu, vaddr, 2))
+ kill_guest(cpu, "bad stack page %#lx", vaddr);
}
+/*:*/
-/*H:450 If we chase down the release_pgd() code, it looks like this: */
-static void release_pgd(struct lguest *lg, pgd_t *spgd)
+#ifdef CONFIG_X86_PAE
+static void release_pmd(pmd_t *spmd)
+{
+ /* If the entry's not present, there's nothing to release. */
+ if (pmd_flags(*spmd) & _PAGE_PRESENT) {
+ unsigned int i;
+ pte_t *ptepage = __va(pmd_pfn(*spmd) << PAGE_SHIFT);
+ /* For each entry in the page, we might need to release it. */
+ for (i = 0; i < PTRS_PER_PTE; i++)
+ release_pte(ptepage[i]);
+ /* Now we can free the page of PTEs */
+ free_page((long)ptepage);
+ /* And zero out the PMD entry so we never release it twice. */
+ set_pmd(spmd, __pmd(0));
+ }
+}
+
+static void release_pgd(pgd_t *spgd)
+{
+ /* If the entry's not present, there's nothing to release. */
+ if (pgd_flags(*spgd) & _PAGE_PRESENT) {
+ unsigned int i;
+ pmd_t *pmdpage = __va(pgd_pfn(*spgd) << PAGE_SHIFT);
+
+ for (i = 0; i < PTRS_PER_PMD; i++)
+ release_pmd(&pmdpage[i]);
+
+ /* Now we can free the page of PMDs */
+ free_page((long)pmdpage);
+ /* And zero out the PGD entry so we never release it twice. */
+ set_pgd(spgd, __pgd(0));
+ }
+}
+
+#else /* !CONFIG_X86_PAE */
+/*H:450
+ * If we chase down the release_pgd() code, the non-PAE version looks like
+ * this. The PAE version is almost identical, but instead of calling
+ * release_pte it calls release_pmd(), which looks much like this.
+ */
+static void release_pgd(pgd_t *spgd)
{
/* If the entry's not present, there's nothing to release. */
if (pgd_flags(*spgd) & _PAGE_PRESENT) {
unsigned int i;
- /* Converting the pfn to find the actual PTE page is easy: turn
+ /*
+ * Converting the pfn to find the actual PTE page is easy: turn
* the page number into a physical address, then convert to a
- * virtual address (easy for kernel pages like this one). */
+ * virtual address (easy for kernel pages like this one).
+ */
pte_t *ptepage = __va(pgd_pfn(*spgd) << PAGE_SHIFT);
/* For each entry in the page, we might need to release it. */
for (i = 0; i < PTRS_PER_PTE; i++)
*spgd = __pgd(0);
}
}
+#endif
-/*H:445 We saw flush_user_mappings() twice: once from the flush_user_mappings()
+/*H:445
+ * We saw flush_user_mappings() twice: once from the flush_user_mappings()
* hypercall and once in new_pgdir() when we re-used a top-level pgdir page.
- * It simply releases every PTE page from 0 up to the Guest's kernel address. */
+ * It simply releases every PTE page from 0 up to the Guest's kernel address.
+ */
static void flush_user_mappings(struct lguest *lg, int idx)
{
unsigned int i;
/* Release every pgd entry up to the kernel's address. */
for (i = 0; i < pgd_index(lg->kernel_address); i++)
- release_pgd(lg, lg->pgdirs[idx].pgdir + i);
+ release_pgd(lg->pgdirs[idx].pgdir + i);
}
-/*H:440 (v) Flushing (throwing away) page tables,
+/*H:440
+ * (v) Flushing (throwing away) page tables,
*
* The Guest has a hypercall to throw away the page tables: it's used when a
- * large number of mappings have been changed. */
-void guest_pagetable_flush_user(struct lguest *lg)
+ * large number of mappings have been changed.
+ */
+void guest_pagetable_flush_user(struct lg_cpu *cpu)
{
/* Drop the userspace part of the current page table. */
- flush_user_mappings(lg, lg->pgdidx);
+ flush_user_mappings(cpu->lg, cpu->cpu_pgd);
}
/*:*/
/* We walk down the guest page tables to get a guest-physical address */
-unsigned long guest_pa(struct lguest *lg, unsigned long vaddr)
+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
/* First step: get the top-level Guest page table entry. */
- gpgd = lgread(lg, gpgd_addr(lg, vaddr), pgd_t);
+ gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t);
/* Toplevel not present? We can't map it in. */
- if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
- kill_guest(lg, "Bad address %#lx", vaddr);
+ if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) {
+ kill_guest(cpu, "Bad address %#lx", vaddr);
+ return -1UL;
+ }
- gpte = lgread(lg, gpte_addr(lg, 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);
+ 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(lg, "Bad address %#lx", vaddr);
+ kill_guest(cpu, "Bad address %#lx", vaddr);
return pte_pfn(gpte) * PAGE_SIZE | (vaddr & ~PAGE_MASK);
}
-/* We keep several page tables. This is a simple routine to find the page
+/*
+ * We keep several page tables. This is a simple routine to find the page
* table (if any) corresponding to this top-level address the Guest has given
- * us. */
+ * us.
+ */
static unsigned int find_pgdir(struct lguest *lg, unsigned long pgtable)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
- if (lg->pgdirs[i].gpgdir == pgtable)
+ if (lg->pgdirs[i].pgdir && lg->pgdirs[i].gpgdir == pgtable)
break;
return i;
}
-/*H:435 And this is us, creating the new page directory. If we really do
+/*H:435
+ * And this is us, creating the new page directory. If we really do
* allocate a new one (and so the kernel parts are not there), we set
- * blank_pgdir. */
-static unsigned int new_pgdir(struct lguest *lg,
+ * blank_pgdir.
+ */
+static unsigned int new_pgdir(struct lg_cpu *cpu,
unsigned long gpgdir,
int *blank_pgdir)
{
unsigned int next;
-
- /* We pick one entry at random to throw out. Choosing the Least
- * Recently Used might be better, but this is easy. */
- next = random32() % ARRAY_SIZE(lg->pgdirs);
+#ifdef CONFIG_X86_PAE
+ pmd_t *pmd_table;
+#endif
+
+ /*
+ * We pick one entry at random to throw out. Choosing the Least
+ * Recently Used might be better, but this is easy.
+ */
+ next = random32() % ARRAY_SIZE(cpu->lg->pgdirs);
/* If it's never been allocated at all before, try now. */
- if (!lg->pgdirs[next].pgdir) {
- lg->pgdirs[next].pgdir = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+ if (!cpu->lg->pgdirs[next].pgdir) {
+ cpu->lg->pgdirs[next].pgdir =
+ (pgd_t *)get_zeroed_page(GFP_KERNEL);
/* If the allocation fails, just keep using the one we have */
- if (!lg->pgdirs[next].pgdir)
- next = lg->pgdidx;
- else
- /* This is a blank page, so there are no kernel
- * mappings: caller must map the stack! */
+ if (!cpu->lg->pgdirs[next].pgdir)
+ next = cpu->cpu_pgd;
+ else {
+#ifdef CONFIG_X86_PAE
+ /*
+ * In PAE mode, allocate a pmd page and populate the
+ * last pgd entry.
+ */
+ pmd_table = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+ if (!pmd_table) {
+ free_page((long)cpu->lg->pgdirs[next].pgdir);
+ set_pgd(cpu->lg->pgdirs[next].pgdir, __pgd(0));
+ next = cpu->cpu_pgd;
+ } else {
+ set_pgd(cpu->lg->pgdirs[next].pgdir +
+ SWITCHER_PGD_INDEX,
+ __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+ /*
+ * This is a blank page, so there are no kernel
+ * mappings: caller must map the stack!
+ */
+ *blank_pgdir = 1;
+ }
+#else
*blank_pgdir = 1;
+#endif
+ }
}
/* Record which Guest toplevel this shadows. */
- lg->pgdirs[next].gpgdir = gpgdir;
+ cpu->lg->pgdirs[next].gpgdir = gpgdir;
/* Release all the non-kernel mappings. */
- flush_user_mappings(lg, next);
+ flush_user_mappings(cpu->lg, next);
return next;
}
-/*H:430 (iv) Switching page tables
+/*H:430
+ * (iv) Switching page tables
*
- * Now we've seen all the page table setting and manipulation, let's see what
+ * Now we've seen all the page table setting and manipulation, let's see
* what happens when the Guest changes page tables (ie. changes the top-level
- * pgdir). This occurs on almost every context switch. */
-void guest_new_pagetable(struct lguest *lg, unsigned long pgtable)
+ * pgdir). This occurs on almost every context switch.
+ */
+void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
{
int newpgdir, repin = 0;
/* Look to see if we have this one already. */
- newpgdir = find_pgdir(lg, pgtable);
- /* If not, we allocate or mug an existing one: if it's a fresh one,
- * repin gets set to 1. */
- if (newpgdir == ARRAY_SIZE(lg->pgdirs))
- newpgdir = new_pgdir(lg, pgtable, &repin);
+ newpgdir = find_pgdir(cpu->lg, pgtable);
+ /*
+ * If not, we allocate or mug an existing one: if it's a fresh one,
+ * repin gets set to 1.
+ */
+ if (newpgdir == ARRAY_SIZE(cpu->lg->pgdirs))
+ newpgdir = new_pgdir(cpu, pgtable, &repin);
/* Change the current pgd index to the new one. */
- lg->pgdidx = newpgdir;
+ cpu->cpu_pgd = newpgdir;
/* If it was completely blank, we map in the Guest kernel stack */
if (repin)
- pin_stack_pages(lg);
+ pin_stack_pages(cpu);
}
-/*H:470 Finally, a routine which throws away everything: all PGD entries in all
+/*H:470
+ * Finally, a routine which throws away everything: all PGD entries in all
* the shadow page tables, including the Guest's kernel mappings. This is used
- * when we destroy the Guest. */
+ * when we destroy the Guest.
+ */
static void release_all_pagetables(struct lguest *lg)
{
unsigned int i, j;
/* Every shadow pagetable this Guest has */
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
- if (lg->pgdirs[i].pgdir)
+ if (lg->pgdirs[i].pgdir) {
+#ifdef CONFIG_X86_PAE
+ pgd_t *spgd;
+ pmd_t *pmdpage;
+ unsigned int k;
+
+ /* Get the last pmd page. */
+ spgd = lg->pgdirs[i].pgdir + SWITCHER_PGD_INDEX;
+ pmdpage = __va(pgd_pfn(*spgd) << PAGE_SHIFT);
+
+ /*
+ * And release the pmd entries of that pmd page,
+ * except for the switcher pmd.
+ */
+ for (k = 0; k < SWITCHER_PMD_INDEX; k++)
+ release_pmd(&pmdpage[k]);
+#endif
/* Every PGD entry except the Switcher at the top */
for (j = 0; j < SWITCHER_PGD_INDEX; j++)
- release_pgd(lg, lg->pgdirs[i].pgdir + j);
+ release_pgd(lg->pgdirs[i].pgdir + j);
+ }
}
-/* We also throw away everything when a Guest tells us it's changed a kernel
+/*
+ * We also throw away everything when a Guest tells us it's changed a kernel
* mapping. Since kernel mappings are in every page table, it's easiest to
* throw them all away. This traps the Guest in amber for a while as
- * everything faults back in, but it's rare. */
-void guest_pagetable_clear_all(struct lguest *lg)
+ * everything faults back in, but it's rare.
+ */
+void guest_pagetable_clear_all(struct lg_cpu *cpu)
{
- release_all_pagetables(lg);
+ release_all_pagetables(cpu->lg);
/* We need the Guest kernel stack mapped again. */
- pin_stack_pages(lg);
+ pin_stack_pages(cpu);
}
/*:*/
-/*M:009 Since we throw away all mappings when a kernel mapping changes, our
+
+/*M:009
+ * Since we throw away all mappings when a kernel mapping changes, our
* performance sucks for guests using highmem. In fact, a guest with
* PAGE_OFFSET 0xc0000000 (the default) and more than about 700MB of RAM is
* usually slower than a Guest with less memory.
*
* This, of course, cannot be fixed. It would take some kind of... well, I
- * don't know, but the term "puissant code-fu" comes to mind. :*/
+ * don't know, but the term "puissant code-fu" comes to mind.
+:*/
-/*H:420 This is the routine which actually sets the page table entry for then
+/*H:420
+ * This is the routine which actually sets the page table entry for then
* "idx"'th shadow page table.
*
* Normally, we can just throw out the old entry and replace it with 0: if they
* _PAGE_ACCESSED then we can put a read-only PTE entry in immediately, and if
* they set _PAGE_DIRTY then we can put a writable PTE entry in immediately.
*/
-static void do_set_pte(struct lguest *lg, int idx,
+static void do_set_pte(struct lg_cpu *cpu, int idx,
unsigned long vaddr, pte_t gpte)
{
/* Look up the matching shadow page directory entry. */
- pgd_t *spgd = spgd_addr(lg, idx, vaddr);
+ pgd_t *spgd = spgd_addr(cpu, idx, vaddr);
+#ifdef CONFIG_X86_PAE
+ pmd_t *spmd;
+#endif
/* If the top level isn't present, there's no entry to update. */
if (pgd_flags(*spgd) & _PAGE_PRESENT) {
- /* Otherwise, we start by releasing the existing entry. */
- pte_t *spte = spte_addr(lg, *spgd, vaddr);
- release_pte(*spte);
-
- /* If they're setting this entry as dirty or accessed, we might
- * as well put that entry they've given us in now. This shaves
- * 10% off a copy-on-write micro-benchmark. */
- if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
- check_gpte(lg, gpte);
- *spte = gpte_to_spte(lg, gpte,
- pte_flags(gpte) & _PAGE_DIRTY);
- } else
- /* Otherwise kill it and we can demand_page() it in
- * later. */
- *spte = __pte(0);
+#ifdef CONFIG_X86_PAE
+ spmd = spmd_addr(cpu, *spgd, vaddr);
+ if (pmd_flags(*spmd) & _PAGE_PRESENT) {
+#endif
+ /* Otherwise, start by releasing the existing entry. */
+ pte_t *spte = spte_addr(cpu, *spgd, vaddr);
+ release_pte(*spte);
+
+ /*
+ * If they're setting this entry as dirty or accessed,
+ * we might as well put that entry they've given us in
+ * now. This shaves 10% off a copy-on-write
+ * micro-benchmark.
+ */
+ if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
+ check_gpte(cpu, gpte);
+ set_pte(spte,
+ gpte_to_spte(cpu, gpte,
+ pte_flags(gpte) & _PAGE_DIRTY));
+ } else {
+ /*
+ * Otherwise kill it and we can demand_page()
+ * it in later.
+ */
+ set_pte(spte, __pte(0));
+ }
+#ifdef CONFIG_X86_PAE
+ }
+#endif
}
}
-/*H:410 Updating a PTE entry is a little trickier.
+/*H:410
+ * Updating a PTE entry is a little trickier.
*
* We keep track of several different page tables (the Guest uses one for each
* process, so it makes sense to cache at least a few). Each of these have
* all processes. So when the page table above that address changes, we update
* all the page tables, not just the current one. This is rare.
*
- * The benefit is that when we have to track a new page table, we can copy keep
- * all the kernel mappings. This speeds up context switch immensely. */
-void guest_set_pte(struct lguest *lg,
+ * The benefit is that when we have to track a new page table, we can keep all
+ * the kernel mappings. This speeds up context switch immensely.
+ */
+void guest_set_pte(struct lg_cpu *cpu,
unsigned long gpgdir, unsigned long vaddr, pte_t gpte)
{
- /* Kernel mappings must be changed on all top levels. Slow, but
- * doesn't happen often. */
- if (vaddr >= lg->kernel_address) {
+ /*
+ * Kernel mappings must be changed on all top levels. Slow, but doesn't
+ * happen often.
+ */
+ if (vaddr >= cpu->lg->kernel_address) {
unsigned int i;
- for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++)
- if (lg->pgdirs[i].pgdir)
- do_set_pte(lg, i, vaddr, gpte);
+ for (i = 0; i < ARRAY_SIZE(cpu->lg->pgdirs); i++)
+ if (cpu->lg->pgdirs[i].pgdir)
+ do_set_pte(cpu, i, vaddr, gpte);
} else {
/* Is this page table one we have a shadow for? */
- int pgdir = find_pgdir(lg, gpgdir);
- if (pgdir != ARRAY_SIZE(lg->pgdirs))
+ int pgdir = find_pgdir(cpu->lg, gpgdir);
+ if (pgdir != ARRAY_SIZE(cpu->lg->pgdirs))
/* If so, do the update. */
- do_set_pte(lg, pgdir, vaddr, gpte);
+ do_set_pte(cpu, pgdir, vaddr, gpte);
}
}
* tells us they've changed. When the Guest tries to use the new entry it will
* fault and demand_page() will fix it up.
*
- * So with that in mind here's our code to to update a (top-level) PGD entry:
+ * So with that in mind here's our code to update a (top-level) PGD entry:
*/
-void guest_set_pmd(struct lguest *lg, unsigned long gpgdir, u32 idx)
+void guest_set_pgd(struct lguest *lg, unsigned long gpgdir, u32 idx)
{
int pgdir;
- /* The kernel seems to try to initialize this early on: we ignore its
- * attempts to map over the Switcher. */
if (idx >= SWITCHER_PGD_INDEX)
return;
pgdir = find_pgdir(lg, gpgdir);
if (pgdir < ARRAY_SIZE(lg->pgdirs))
/* ... throw it away. */
- release_pgd(lg, lg->pgdirs[pgdir].pgdir + idx);
+ release_pgd(lg->pgdirs[pgdir].pgdir + idx);
}
-/*H:500 (vii) Setting up the page tables initially.
+#ifdef CONFIG_X86_PAE
+/* For setting a mid-level, we just throw everything away. It's easy. */
+void guest_set_pmd(struct lguest *lg, unsigned long pmdp, u32 idx)
+{
+ guest_pagetable_clear_all(&lg->cpus[0]);
+}
+#endif
+
+/*H:505
+ * To get through boot, we construct simple identity page mappings (which
+ * set virtual == physical) and linear mappings which will get the Guest far
+ * enough into the boot to create its own. The linear mapping means we
+ * simplify the Guest boot, but it makes assumptions about their PAGE_OFFSET,
+ * as you'll see.
+ *
+ * We lay them out of the way, just below the initrd (which is why we need to
+ * know its size here).
+ */
+static unsigned long setup_pagetables(struct lguest *lg,
+ unsigned long mem,
+ unsigned long initrd_size)
+{
+ pgd_t __user *pgdir;
+ pte_t __user *linear;
+ unsigned long mem_base = (unsigned long)lg->mem_base;
+ unsigned int mapped_pages, i, linear_pages;
+#ifdef CONFIG_X86_PAE
+ pmd_t __user *pmds;
+ unsigned int j;
+ pgd_t pgd;
+ pmd_t pmd;
+#else
+ unsigned int phys_linear;
+#endif
+
+ /*
+ * We have mapped_pages frames to map, so we need linear_pages page
+ * tables to map them.
+ */
+ mapped_pages = mem / PAGE_SIZE;
+ linear_pages = (mapped_pages + PTRS_PER_PTE - 1) / PTRS_PER_PTE;
+
+ /* We put the toplevel page directory page at the top of memory. */
+ pgdir = (pgd_t *)(mem + mem_base - initrd_size - PAGE_SIZE);
+
+ /* Now we use the next linear_pages pages as pte pages */
+ linear = (void *)pgdir - linear_pages * PAGE_SIZE;
+
+#ifdef CONFIG_X86_PAE
+ /*
+ * And the single mid page goes below that. We only use one, but
+ * that's enough to map 1G, which definitely gets us through boot.
+ */
+ pmds = (void *)linear - PAGE_SIZE;
+#endif
+ /*
+ * Linear mapping is easy: put every page's address into the
+ * mapping in order.
+ */
+ for (i = 0; i < mapped_pages; i++) {
+ pte_t pte;
+ pte = pfn_pte(i, __pgprot(_PAGE_PRESENT|_PAGE_RW|_PAGE_USER));
+ if (copy_to_user(&linear[i], &pte, sizeof(pte)) != 0)
+ return -EFAULT;
+ }
+
+#ifdef CONFIG_X86_PAE
+ /*
+ * Make the Guest PMD entries point to the corresponding place in the
+ * linear mapping (up to one page worth of PMD).
+ */
+ for (i = j = 0; i < mapped_pages && j < PTRS_PER_PMD;
+ i += PTRS_PER_PTE, j++) {
+ pmd = pfn_pmd(((unsigned long)&linear[i] - mem_base)/PAGE_SIZE,
+ __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER));
+
+ if (copy_to_user(&pmds[j], &pmd, sizeof(pmd)) != 0)
+ return -EFAULT;
+ }
+
+ /* One PGD entry, pointing to that PMD page. */
+ pgd = __pgd(((unsigned long)pmds - mem_base) | _PAGE_PRESENT);
+ /* Copy it in as the first PGD entry (ie. addresses 0-1G). */
+ if (copy_to_user(&pgdir[0], &pgd, sizeof(pgd)) != 0)
+ return -EFAULT;
+ /*
+ * And the other PGD entry to make the linear mapping at PAGE_OFFSET
+ */
+ if (copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd)))
+ return -EFAULT;
+#else
+ /*
+ * The top level points to the linear page table pages above.
+ * We setup the identity and linear mappings here.
+ */
+ phys_linear = (unsigned long)linear - mem_base;
+ for (i = 0; i < mapped_pages; i += PTRS_PER_PTE) {
+ pgd_t pgd;
+ /*
+ * Create a PGD entry which points to the right part of the
+ * linear PTE pages.
+ */
+ pgd = __pgd((phys_linear + i * sizeof(pte_t)) |
+ (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER));
+
+ /*
+ * Copy it into the PGD page at 0 and PAGE_OFFSET.
+ */
+ if (copy_to_user(&pgdir[i / PTRS_PER_PTE], &pgd, sizeof(pgd))
+ || copy_to_user(&pgdir[pgd_index(PAGE_OFFSET)
+ + i / PTRS_PER_PTE],
+ &pgd, sizeof(pgd)))
+ return -EFAULT;
+ }
+#endif
+
+ /*
+ * We return the top level (guest-physical) address: we remember where
+ * this is to write it into lguest_data when the Guest initializes.
+ */
+ return (unsigned long)pgdir - mem_base;
+}
+
+/*H:500
+ * (vii) Setting up the page tables initially.
*
* When a Guest is first created, the Launcher tells us where the toplevel of
- * its first page table is. We set some things up here: */
-int init_guest_pagetable(struct lguest *lg, unsigned long pgtable)
-{
- /* We start on the first shadow page table, and give it a blank PGD
- * page. */
- lg->pgdidx = 0;
- lg->pgdirs[lg->pgdidx].gpgdir = pgtable;
- lg->pgdirs[lg->pgdidx].pgdir = (pgd_t*)get_zeroed_page(GFP_KERNEL);
- if (!lg->pgdirs[lg->pgdidx].pgdir)
+ * its first page table is. We set some things up here:
+ */
+int init_guest_pagetable(struct lguest *lg)
+{
+ u64 mem;
+ u32 initrd_size;
+ struct boot_params __user *boot = (struct boot_params *)lg->mem_base;
+#ifdef CONFIG_X86_PAE
+ pgd_t *pgd;
+ pmd_t *pmd_table;
+#endif
+ /*
+ * Get the Guest memory size and the ramdisk size from the boot header
+ * located at lg->mem_base (Guest address 0).
+ */
+ if (copy_from_user(&mem, &boot->e820_map[0].size, sizeof(mem))
+ || get_user(initrd_size, &boot->hdr.ramdisk_size))
+ return -EFAULT;
+
+ /*
+ * We start on the first shadow page table, and give it a blank PGD
+ * page.
+ */
+ lg->pgdirs[0].gpgdir = setup_pagetables(lg, mem, initrd_size);
+ if (IS_ERR_VALUE(lg->pgdirs[0].gpgdir))
+ return lg->pgdirs[0].gpgdir;
+ lg->pgdirs[0].pgdir = (pgd_t *)get_zeroed_page(GFP_KERNEL);
+ if (!lg->pgdirs[0].pgdir)
+ return -ENOMEM;
+
+#ifdef CONFIG_X86_PAE
+ /* For PAE, we also create the initial mid-level. */
+ pgd = lg->pgdirs[0].pgdir;
+ pmd_table = (pmd_t *) get_zeroed_page(GFP_KERNEL);
+ if (!pmd_table)
return -ENOMEM;
+
+ set_pgd(pgd + SWITCHER_PGD_INDEX,
+ __pgd(__pa(pmd_table) | _PAGE_PRESENT));
+#endif
+
+ /* This is the current page table. */
+ lg->cpus[0].cpu_pgd = 0;
return 0;
}
-/* When the Guest calls LHCALL_LGUEST_INIT we do more setup. */
-void page_table_guest_data_init(struct lguest *lg)
+/*H:508 When the Guest calls LHCALL_LGUEST_INIT we do more setup. */
+void page_table_guest_data_init(struct lg_cpu *cpu)
{
/* We get the kernel address: above this is all kernel memory. */
- if (get_user(lg->kernel_address, &lg->lguest_data->kernel_address)
- /* We tell the Guest that it can't use the top 4MB of virtual
- * addresses used by the Switcher. */
- || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
- || put_user(lg->pgdirs[lg->pgdidx].gpgdir,&lg->lguest_data->pgdir))
- kill_guest(lg, "bad guest page %p", lg->lguest_data);
-
- /* In flush_user_mappings() we loop from 0 to
+ if (get_user(cpu->lg->kernel_address,
+ &cpu->lg->lguest_data->kernel_address)
+ /*
+ * We tell the Guest that it can't use the top 2 or 4 MB
+ * of virtual addresses used by the Switcher.
+ */
+ || put_user(RESERVE_MEM * 1024 * 1024,
+ &cpu->lg->lguest_data->reserve_mem)
+ || put_user(cpu->lg->pgdirs[0].gpgdir,
+ &cpu->lg->lguest_data->pgdir))
+ kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
+
+ /*
+ * In flush_user_mappings() we loop from 0 to
* "pgd_index(lg->kernel_address)". This assumes it won't hit the
- * Switcher mappings, so check that now. */
- if (pgd_index(lg->kernel_address) >= SWITCHER_PGD_INDEX)
- kill_guest(lg, "bad kernel address %#lx", lg->kernel_address);
+ * Switcher mappings, so check that now.
+ */
+#ifdef CONFIG_X86_PAE
+ if (pgd_index(cpu->lg->kernel_address) == SWITCHER_PGD_INDEX &&
+ pmd_index(cpu->lg->kernel_address) == SWITCHER_PMD_INDEX)
+#else
+ if (pgd_index(cpu->lg->kernel_address) >= SWITCHER_PGD_INDEX)
+#endif
+ kill_guest(cpu, "bad kernel address %#lx",
+ cpu->lg->kernel_address);
}
/* When a Guest dies, our cleanup is fairly simple. */
free_page((long)lg->pgdirs[i].pgdir);
}
-/*H:480 (vi) Mapping the Switcher when the Guest is about to run.
+/*H:480
+ * (vi) Mapping the Switcher when the Guest is about to run.
*
* The Switcher and the two pages for this CPU need to be visible in the
* Guest (and not the pages for other CPUs). We have the appropriate PTE pages
* for each CPU already set up, we just need to hook them in now we know which
- * Guest is about to run on this CPU. */
-void map_switcher_in_guest(struct lguest *lg, struct lguest_pages *pages)
+ * Guest is about to run on this CPU.
+ */
+void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages)
{
pte_t *switcher_pte_page = __get_cpu_var(switcher_pte_pages);
- pgd_t switcher_pgd;
pte_t regs_pte;
- /* Make the last PGD entry for this Guest point to the Switcher's PTE
- * page for this CPU (with appropriate flags). */
- switcher_pgd = __pgd(__pa(switcher_pte_page) | _PAGE_KERNEL);
+#ifdef CONFIG_X86_PAE
+ pmd_t switcher_pmd;
+ pmd_t *pmd_table;
+
+ switcher_pmd = pfn_pmd(__pa(switcher_pte_page) >> PAGE_SHIFT,
+ PAGE_KERNEL_EXEC);
+
+ /* Figure out where the pmd page is, by reading the PGD, and converting
+ * it to a virtual address. */
+ pmd_table = __va(pgd_pfn(cpu->lg->
+ pgdirs[cpu->cpu_pgd].pgdir[SWITCHER_PGD_INDEX])
+ << PAGE_SHIFT);
+ /* Now write it into the shadow page table. */
+ set_pmd(&pmd_table[SWITCHER_PMD_INDEX], switcher_pmd);
+#else
+ pgd_t switcher_pgd;
+
+ /*
+ * Make the last PGD entry for this Guest point to the Switcher's PTE
+ * page for this CPU (with appropriate flags).
+ */
+ switcher_pgd = __pgd(__pa(switcher_pte_page) | __PAGE_KERNEL_EXEC);
- lg->pgdirs[lg->pgdidx].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
+ cpu->lg->pgdirs[cpu->cpu_pgd].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
- /* We also change the Switcher PTE page. When we're running the Guest,
+#endif
+ /*
+ * We also change the Switcher PTE page. When we're running the Guest,
* we want the Guest's "regs" page to appear where the first Switcher
* page for this CPU is. This is an optimization: when the Switcher
* saves the Guest registers, it saves them into the first page of this
* CPU's "struct lguest_pages": if we make sure the Guest's register
* page is already mapped there, we don't have to copy them out
- * again. */
- regs_pte = pfn_pte (__pa(lg->regs_page) >> PAGE_SHIFT, __pgprot(_PAGE_KERNEL));
- switcher_pte_page[(unsigned long)pages/PAGE_SIZE%PTRS_PER_PTE] = regs_pte;
+ * again.
+ */
+ regs_pte = pfn_pte(__pa(cpu->regs_page) >> PAGE_SHIFT, PAGE_KERNEL);
+ set_pte(&switcher_pte_page[pte_index((unsigned long)pages)], regs_pte);
}
/*:*/
free_page((long)switcher_pte_page(i));
}
-/*H:520 Setting up the Switcher PTE page for given CPU is fairly easy, given
+/*H:520
+ * Setting up the Switcher PTE page for given CPU is fairly easy, given
* the CPU number and the "struct page"s for the Switcher code itself.
*
- * Currently the Switcher is less than a page long, so "pages" is always 1. */
+ * Currently the Switcher is less than a page long, so "pages" is always 1.
+ */
static __init void populate_switcher_pte_page(unsigned int cpu,
struct page *switcher_page[],
unsigned int pages)
/* The first entries are easy: they map the Switcher code. */
for (i = 0; i < pages; i++) {
- pte[i] = mk_pte(switcher_page[i],
- __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED));
+ set_pte(&pte[i], mk_pte(switcher_page[i],
+ __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));
}
/* The only other thing we map is this CPU's pair of pages. */
i = pages + cpu*2;
/* First page (Guest registers) is writable from the Guest */
- pte[i] = pfn_pte(page_to_pfn(switcher_page[i]),
- __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW));
-
- /* The second page contains the "struct lguest_ro_state", and is
- * read-only. */
- pte[i+1] = pfn_pte(page_to_pfn(switcher_page[i+1]),
- __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED));
+ set_pte(&pte[i], pfn_pte(page_to_pfn(switcher_page[i]),
+ __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW)));
+
+ /*
+ * The second page contains the "struct lguest_ro_state", and is
+ * read-only.
+ */
+ set_pte(&pte[i+1], pfn_pte(page_to_pfn(switcher_page[i+1]),
+ __pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));
}
-/* We've made it through the page table code. Perhaps our tired brains are
+/*
+ * We've made it through the page table code. Perhaps our tired brains are
* still processing the details, or perhaps we're simply glad it's over.
*
- * If nothing else, note that all this complexity in juggling shadow page
- * tables in sync with the Guest's page tables is for one reason: for most
- * Guests this page table dance determines how bad performance will be. This
- * is why Xen uses exotic direct Guest pagetable manipulation, and why both
- * Intel and AMD have implemented shadow page table support directly into
- * hardware.
+ * If nothing else, note that all this complexity in juggling shadow page tables
+ * in sync with the Guest's page tables is for one reason: for most Guests this
+ * page table dance determines how bad performance will be. This is why Xen
+ * uses exotic direct Guest pagetable manipulation, and why both Intel and AMD
+ * have implemented shadow page table support directly into hardware.
*
- * There is just one file remaining in the Host. */
+ * There is just one file remaining in the Host.
+ */
-/*H:510 At boot or module load time, init_pagetables() allocates and populates
- * the Switcher PTE page for each CPU. */
+/*H:510
+ * At boot or module load time, init_pagetables() allocates and populates
+ * the Switcher PTE page for each CPU.
+ */
__init int init_pagetables(struct page **switcher_page, unsigned int pages)
{
unsigned int i;
Code Review / linux-3.10.git / blobdiff