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Lots of virtio work which wasn't quite ready for last merge window. Plus

Browse source 
I dived into lguest again, reworking the pagetable code so we can move
 the switcher page: our fixmaps sometimes take more than 2MB now...
 
 Cheers,
 Rusty.
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Merge tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux

Pull virtio & lguest updates from Rusty Russell:
 "Lots of virtio work which wasn't quite ready for last merge window.

  Plus I dived into lguest again, reworking the pagetable code so we can
  move the switcher page: our fixmaps sometimes take more than 2MB now..."

Ugh.  Annoying conflicts with the tcm_vhost -> vhost_scsi rename.
Hopefully correctly resolved.

* tag 'virtio-next-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux: (57 commits)
  caif_virtio: Remove bouncing email addresses
  lguest: improve code readability in lg_cpu_start.
  virtio-net: fill only rx queues which are being used
  lguest: map Switcher below fixmap.
  lguest: cache last cpu we ran on.
  lguest: map Switcher text whenever we allocate a new pagetable.
  lguest: don't share Switcher PTE pages between guests.
  lguest: expost switcher_pages array (as lg_switcher_pages).
  lguest: extract shadow PTE walking / allocating.
  lguest: make check_gpte et. al return bool.
  lguest: assume Switcher text is a single page.
  lguest: rename switcher_page to switcher_pages.
  lguest: remove RESERVE_MEM constant.
  lguest: check vaddr not pgd for Switcher protection.
  lguest: prepare to make SWITCHER_ADDR a variable.
  virtio: console: replace EMFILE with EBUSY for already-open port
  virtio-scsi: reset virtqueue affinity when doing cpu hotplug
  virtio-scsi: introduce multiqueue support
  virtio-scsi: push vq lock/unlock into virtscsi_vq_done
  virtio-scsi: pass struct virtio_scsi to virtqueue completion function
  ...
This commit is contained in:
Linus Torvalds 2013-05-02 14:14:04 -07:00
commit 736a2dd257
60 changed files with 4481 additions and 4074 deletions
Download patch file Download diff file Expand all files Collapse all files

5
drivers/lguest/Kconfig
View file

@ -5,10 +5,9 @@ config LGUEST
---help---
This is a very simple module which allows you to run
multiple instances of the same Linux kernel, using the
"lguest" command found in the Documentation/virtual/lguest
directory.
"lguest" command found in the tools/lguest directory.
Note that "lguest" is pronounced to rhyme with "fell quest",
not "rustyvisor". See Documentation/virtual/lguest/lguest.txt.
not "rustyvisor". See tools/lguest/lguest.txt.
If unsure, say N. If curious, say M. If masochistic, say Y.

67
drivers/lguest/core.c
View file

@ -20,9 +20,9 @@
#include <asm/asm-offsets.h>
#include "lg.h"
unsigned long switcher_addr;
struct page **lg_switcher_pages;
static struct vm_struct *switcher_vma;
static struct page **switcher_page;
/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);
@ -52,13 +52,21 @@ static __init int map_switcher(void)
* easy.
*/
/* We assume Switcher text fits into a single page. */
if (end_switcher_text - start_switcher_text > PAGE_SIZE) {
printk(KERN_ERR "lguest: switcher text too large (%zu)\n",
end_switcher_text - start_switcher_text);
return -EINVAL;
}
/*
* We allocate an array of struct page pointers. map_vm_area() wants
* this, rather than just an array of pages.
*/
switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!switcher_page) {
lg_switcher_pages = kmalloc(sizeof(lg_switcher_pages[0])
* TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!lg_switcher_pages) {
err = -ENOMEM;
goto out;
}
@ -68,32 +76,29 @@ static __init int map_switcher(void)
* so we make sure they're zeroed.
*/
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
switcher_page[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
if (!switcher_page[i]) {
lg_switcher_pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
if (!lg_switcher_pages[i]) {
err = -ENOMEM;
goto free_some_pages;
}
}
/*
* First we check that the Switcher won't overlap the fixmap area at
* the top of memory. It's currently nowhere near, but it could have
* very strange effects if it ever happened.
* We place the Switcher underneath the fixmap area, which is the
* highest virtual address we can get. This is important, since we
* tell the Guest it can't access this memory, so we want its ceiling
* as high as possible.
*/
if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
err = -ENOMEM;
printk("lguest: mapping switcher would thwack fixmap\n");
goto free_pages;
}
switcher_addr = FIXADDR_START - (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE;
/*
* Now we reserve the "virtual memory area" we want: 0xFFC00000
* (SWITCHER_ADDR). We might not get it in theory, but in practice
* it's worked so far. The end address needs +1 because __get_vm_area
* allocates an extra guard page, so we need space for that.
* Now we reserve the "virtual memory area" we want. We might
* not get it in theory, but in practice it's worked so far.
* The end address needs +1 because __get_vm_area allocates an
* extra guard page, so we need space for that.
*/
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
VM_ALLOC, switcher_addr, switcher_addr
+ (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
if (!switcher_vma) {
err = -ENOMEM;
@ -103,12 +108,12 @@ static __init int map_switcher(void)
/*
* This code actually sets up the pages we've allocated to appear at
* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
* switcher_addr. map_vm_area() takes the vma we allocated above, the
* kind of pages we're mapping (kernel pages), and a pointer to our
* array of struct pages. It increments that pointer, but we don't
* care.
*/
pagep = switcher_page;
pagep = lg_switcher_pages;
err = map_vm_area(switcher_vma, PAGE_KERNEL_EXEC, &pagep);
if (err) {
printk("lguest: map_vm_area failed: %i\n", err);
@ -133,8 +138,8 @@ free_pages:
i = TOTAL_SWITCHER_PAGES;
free_some_pages:
for (--i; i >= 0; i--)
__free_pages(switcher_page[i], 0);
kfree(switcher_page);
__free_pages(lg_switcher_pages[i], 0);
kfree(lg_switcher_pages);
out:
return err;
}
@ -149,8 +154,8 @@ static void unmap_switcher(void)
vunmap(switcher_vma->addr);
/* Now we just need to free the pages we copied the switcher into */
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++)
__free_pages(switcher_page[i], 0);
kfree(switcher_page);
__free_pages(lg_switcher_pages[i], 0);
kfree(lg_switcher_pages);
}
/*H:032
@ -323,15 +328,10 @@ static int __init init(void)
if (err)
goto out;
/* Now we set up the pagetable implementation for the Guests. */
err = init_pagetables(switcher_page, SHARED_SWITCHER_PAGES);
if (err)
goto unmap;
/* We might need to reserve an interrupt vector. */
err = init_interrupts();
if (err)
goto free_pgtables;
goto unmap;
/* /dev/lguest needs to be registered. */
err = lguest_device_init();
@ -346,8 +346,6 @@ static int __init init(void)
free_interrupts:
free_interrupts();
free_pgtables:
free_pagetables();
unmap:
unmap_switcher();
out:
@ -359,7 +357,6 @@ static void __exit fini(void)
{
lguest_device_remove();
free_interrupts();
free_pagetables();
unmap_switcher();
lguest_arch_host_fini();

6
drivers/lguest/lg.h
View file

@ -14,11 +14,10 @@
#include <asm/lguest.h>
void free_pagetables(void);
int init_pagetables(struct page **switcher_page, unsigned int pages);
struct pgdir {
unsigned long gpgdir;
bool switcher_mapped;
int last_host_cpu;
pgd_t *pgdir;
};
@ -124,6 +123,7 @@ bool lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len);
void __lgread(struct lg_cpu *, void *, unsigned long, unsigned);
void __lgwrite(struct lg_cpu *, unsigned long, const void *, unsigned);
extern struct page **lg_switcher_pages;
/*H:035
* Using memory-copy operations like that is usually inconvient, so we

6
drivers/lguest/lguest_user.c
View file

@ -250,13 +250,13 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
*/
static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
{
/* We have a limited number the number of CPUs in the lguest struct. */
/* We have a limited number of CPUs in the lguest struct. */
if (id >= ARRAY_SIZE(cpu->lg->cpus))
return -EINVAL;
/* Set up this CPU's id, and pointer back to the lguest struct. */
cpu->id = id;
cpu->lg = container_of((cpu - id), struct lguest, cpus[0]);
cpu->lg = container_of(cpu, struct lguest, cpus[id]);
cpu->lg->nr_cpus++;
/* Each CPU has a timer it can set. */
@ -270,7 +270,7 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip)
if (!cpu->regs_page)
return -ENOMEM;
/* We actually put the registers at the bottom of the page. */
/* We actually put the registers at the end of the page. */
cpu->regs = (void *)cpu->regs_page + PAGE_SIZE - sizeof(*cpu->regs);
/*

573
drivers/lguest/page_tables.c
View file

@ -7,7 +7,7 @@
* converted Guest pages when running the Guest.
:*/
/* Copyright (C) Rusty Russell IBM Corporation 2006.
/* Copyright (C) Rusty Russell IBM Corporation 2013.
* GPL v2 and any later version */
#include <linux/mm.h>
#include <linux/gfp.h>
@ -62,22 +62,11 @@
* 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.
*/
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. The kernel itself provides many of them; one advantage
@ -95,13 +84,6 @@ 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(cpu, "attempt to access switcher pages");
index = 0;
}
#endif
/* Return a pointer index'th pgd entry for the i'th page table. */
return &cpu->lg->pgdirs[i].pgdir[index];
}
@ -117,13 +99,6 @@ 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);
@ -275,29 +250,120 @@ static void release_pte(pte_t pte)
}
/*:*/
static void check_gpte(struct lg_cpu *cpu, pte_t gpte)
static bool check_gpte(struct lg_cpu *cpu, pte_t gpte)
{
if ((pte_flags(gpte) & _PAGE_PSE) ||
pte_pfn(gpte) >= cpu->lg->pfn_limit)
pte_pfn(gpte) >= cpu->lg->pfn_limit) {
kill_guest(cpu, "bad page table entry");
return false;
}
return true;
}
static void check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
static bool check_gpgd(struct lg_cpu *cpu, pgd_t gpgd)
{
if ((pgd_flags(gpgd) & ~CHECK_GPGD_MASK) ||
(pgd_pfn(gpgd) >= cpu->lg->pfn_limit))
(pgd_pfn(gpgd) >= cpu->lg->pfn_limit)) {
kill_guest(cpu, "bad page directory entry");
return false;
}
return true;
}
#ifdef CONFIG_X86_PAE
static void check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
static bool check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
{
if ((pmd_flags(gpmd) & ~_PAGE_TABLE) ||
(pmd_pfn(gpmd) >= cpu->lg->pfn_limit))
(pmd_pfn(gpmd) >= cpu->lg->pfn_limit)) {
kill_guest(cpu, "bad page middle directory entry");
return false;
}
return true;
}
#endif
/*H:331
* This is the core routine to walk the shadow page tables and find the page
* table entry for a specific address.
*
* If allocate is set, then we allocate any missing levels, setting the flags
* on the new page directory and mid-level directories using the arguments
* (which are copied from the Guest's page table entries).
*/
static pte_t *find_spte(struct lg_cpu *cpu, unsigned long vaddr, bool allocate,
int pgd_flags, int pmd_flags)
{
pgd_t *spgd;
/* Mid level for PAE. */
#ifdef CONFIG_X86_PAE
pmd_t *spmd;
#endif
/* Get top level entry. */
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;
/* If they didn't want us to allocate anything, stop. */
if (!allocate)
return NULL;
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 NULL;
}
/*
* 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));
}
/*
* Intel's Physical Address Extension actually uses three levels of
* page tables, so we need to look in the mid-level.
*/
#ifdef CONFIG_X86_PAE
/* Now look at the mid-level 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;
/* If they didn't want us to allocate anything, stop. */
if (!allocate)
return NULL;
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 pmd page");
return NULL;
}
/*
* 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));
}
#endif
/* Get the pointer to the shadow PTE entry we're going to set. */
return spte_addr(cpu, *spgd, vaddr);
}
/*H:330
* (i) Looking up a page table entry when the Guest faults.
*
@ -311,17 +377,15 @@ static void check_gpmd(struct lg_cpu *cpu, pmd_t gpmd)
*/
bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
{
pgd_t gpgd;
pgd_t *spgd;
unsigned long gpte_ptr;
pte_t gpte;
pte_t *spte;
/* Mid level for PAE. */
#ifdef CONFIG_X86_PAE
pmd_t *spmd;
pmd_t gpmd;
#endif
pgd_t gpgd;
/* We never demand page the Switcher, so trying is a mistake. */
if (vaddr >= switcher_addr)
return false;
/* First step: get the top-level Guest page table entry. */
if (unlikely(cpu->linear_pages)) {
@ -332,65 +396,31 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
/* Toplevel not present? We can't map it in. */
if (!(pgd_flags(gpgd) & _PAGE_PRESENT))
return false;
/*
* This kills the Guest if it has weird flags or tries to
* refer to a "physical" address outside the bounds.
*/
if (!check_gpgd(cpu, gpgd))
return false;
}
/* Now look at the matching shadow entry. */
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.
*/
if (!ptepage) {
kill_guest(cpu, "out of memory allocating pte page");
return false;
}
/* We check that the Guest pgd is OK. */
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)));
}
/* This "mid-level" entry is only used for non-linear, PAE mode. */
gpmd = __pmd(_PAGE_TABLE);
#ifdef CONFIG_X86_PAE
if (unlikely(cpu->linear_pages)) {
/* Faking up a linear mapping. */
gpmd = __pmd(_PAGE_TABLE);
} else {
if (likely(!cpu->linear_pages)) {
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.
/*
* This kills the Guest if it has weird flags or tries to
* refer to a "physical" address outside the bounds.
*/
if (!ptepage) {
kill_guest(cpu, "out of memory allocating pte page");
if (!check_gpmd(cpu, gpmd))
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)));
}
/*
@ -433,7 +463,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
* 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);
if (!check_gpte(cpu, gpte))
return false;
/* Add the _PAGE_ACCESSED and (for a write) _PAGE_DIRTY flag */
gpte = pte_mkyoung(gpte);
@ -441,7 +472,9 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
gpte = pte_mkdirty(gpte);
/* Get the pointer to the shadow PTE entry we're going to set. */
spte = spte_addr(cpu, *spgd, vaddr);
spte = find_spte(cpu, vaddr, true, pgd_flags(gpgd), pmd_flags(gpmd));
if (!spte)
return false;
/*
* If there was a valid shadow PTE entry here before, we release it.
@ -493,29 +526,23 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode)
*/
static bool page_writable(struct lg_cpu *cpu, unsigned long vaddr)
{
pgd_t *spgd;
pte_t *spte;
unsigned long flags;
#ifdef CONFIG_X86_PAE
pmd_t *spmd;
#endif
/* Look at the current top level entry: is it present? */
spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr);
if (!(pgd_flags(*spgd) & _PAGE_PRESENT))
/* You can't put your stack in the Switcher! */
if (vaddr >= switcher_addr)
return false;
#ifdef CONFIG_X86_PAE
spmd = spmd_addr(cpu, *spgd, vaddr);
if (!(pmd_flags(*spmd) & _PAGE_PRESENT))
/* If there's no shadow PTE, it's not writable. */
spte = find_spte(cpu, vaddr, false, 0, 0);
if (!spte)
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)));
flags = pte_flags(*spte);
return (flags & (_PAGE_PRESENT|_PAGE_RW)) == (_PAGE_PRESENT|_PAGE_RW);
}
@ -678,9 +705,6 @@ static unsigned int new_pgdir(struct lg_cpu *cpu,
int *blank_pgdir)
{
unsigned int next;
#ifdef CONFIG_X86_PAE
pmd_t *pmd_table;
#endif
/*
* We pick one entry at random to throw out. Choosing the Least
@ -695,29 +719,11 @@ static unsigned int new_pgdir(struct lg_cpu *cpu,
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.
* This is a blank page, so there are no kernel
* mappings: caller must map the stack!
*/
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. */
@ -725,9 +731,50 @@ static unsigned int new_pgdir(struct lg_cpu *cpu,
/* Release all the non-kernel mappings. */
flush_user_mappings(cpu->lg, next);
/* This hasn't run on any CPU at all. */
cpu->lg->pgdirs[next].last_host_cpu = -1;
return next;
}
/*H:501
* We do need the Switcher code mapped at all times, so we allocate that
* part of the Guest page table here. We map the Switcher code immediately,
* but defer mapping of the guest register page and IDT/LDT etc page until
* just before we run the guest in map_switcher_in_guest().
*
* We *could* do this setup in map_switcher_in_guest(), but at that point
* we've interrupts disabled, and allocating pages like that is fraught: we
* can't sleep if we need to free up some memory.
*/
static bool allocate_switcher_mapping(struct lg_cpu *cpu)
{
int i;
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
pte_t *pte = find_spte(cpu, switcher_addr + i * PAGE_SIZE, true,
CHECK_GPGD_MASK, _PAGE_TABLE);
if (!pte)
return false;
/*
* Map the switcher page if not already there. It might
* already be there because we call allocate_switcher_mapping()
* in guest_set_pgd() just in case it did discard our Switcher
* mapping, but it probably didn't.
*/
if (i == 0 && !(pte_flags(*pte) & _PAGE_PRESENT)) {
/* Get a reference to the Switcher page. */
get_page(lg_switcher_pages[0]);
/* Create a read-only, exectuable, kernel-style PTE */
set_pte(pte,
mk_pte(lg_switcher_pages[0], PAGE_KERNEL_RX));
}
}
cpu->lg->pgdirs[cpu->cpu_pgd].switcher_mapped = true;
return true;
}
/*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
@ -738,28 +785,16 @@ 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) {
#ifdef CONFIG_X86_PAE
pgd_t *spgd;
pmd_t *pmdpage;
unsigned int k;
for (i = 0; i < ARRAY_SIZE(lg->pgdirs); i++) {
if (!lg->pgdirs[i].pgdir)
continue;
/* 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->pgdirs[i].pgdir + j);
}
/* Every PGD entry. */
for (j = 0; j < PTRS_PER_PGD; j++)
release_pgd(lg->pgdirs[i].pgdir + j);
lg->pgdirs[i].switcher_mapped = false;
lg->pgdirs[i].last_host_cpu = -1;
}
}
/*
@ -773,6 +808,9 @@ void guest_pagetable_clear_all(struct lg_cpu *cpu)
release_all_pagetables(cpu->lg);
/* We need the Guest kernel stack mapped again. */
pin_stack_pages(cpu);
/* And we need Switcher allocated. */
if (!allocate_switcher_mapping(cpu))
kill_guest(cpu, "Cannot populate switcher mapping");
}
/*H:430
@ -808,9 +846,17 @@ void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable)
newpgdir = new_pgdir(cpu, pgtable, &repin);
/* Change the current pgd index to the new one. */
cpu->cpu_pgd = newpgdir;
/* If it was completely blank, we map in the Guest kernel stack */
/*
* If it was completely blank, we map in the Guest kernel stack and
* the Switcher.
*/
if (repin)
pin_stack_pages(cpu);
if (!cpu->lg->pgdirs[cpu->cpu_pgd].switcher_mapped) {
if (!allocate_switcher_mapping(cpu))
kill_guest(cpu, "Cannot populate switcher mapping");
}
}
/*:*/
@ -865,7 +911,8 @@ static void do_set_pte(struct lg_cpu *cpu, int idx,
* micro-benchmark.
*/
if (pte_flags(gpte) & (_PAGE_DIRTY | _PAGE_ACCESSED)) {
check_gpte(cpu, gpte);
if (!check_gpte(cpu, gpte))
return;
set_pte(spte,
gpte_to_spte(cpu, gpte,
pte_flags(gpte) & _PAGE_DIRTY));
@ -897,6 +944,12 @@ static void do_set_pte(struct lg_cpu *cpu, int idx,
void guest_set_pte(struct lg_cpu *cpu,
unsigned long gpgdir, unsigned long vaddr, pte_t gpte)
{
/* We don't let you remap the Switcher; we need it to get back! */
if (vaddr >= switcher_addr) {
kill_guest(cpu, "attempt to set pte into Switcher pages");
return;
}
/*
* Kernel mappings must be changed on all top levels. Slow, but doesn't
* happen often.
@ -933,14 +986,23 @@ void guest_set_pgd(struct lguest *lg, unsigned long gpgdir, u32 idx)
{
int pgdir;
if (idx >= SWITCHER_PGD_INDEX)
if (idx > PTRS_PER_PGD) {
kill_guest(&lg->cpus[0], "Attempt to set pgd %u/%u",
idx, PTRS_PER_PGD);
return;
}
/* If they're talking about a page table we have a shadow for... */
pgdir = find_pgdir(lg, gpgdir);
if (pgdir < ARRAY_SIZE(lg->pgdirs))
if (pgdir < ARRAY_SIZE(lg->pgdirs)) {
/* ... throw it away. */
release_pgd(lg->pgdirs[pgdir].pgdir + idx);
/* That might have been the Switcher mapping, remap it. */
if (!allocate_switcher_mapping(&lg->cpus[0])) {
kill_guest(&lg->cpus[0],
"Cannot populate switcher mapping");
}
}
}
#ifdef CONFIG_X86_PAE
@ -958,6 +1020,9 @@ void guest_set_pmd(struct lguest *lg, unsigned long pmdp, u32 idx)
* we will populate on future faults. The Guest doesn't have any actual
* pagetables yet, so we set linear_pages to tell demand_page() to fake it
* for the moment.
*
* We do need the Switcher to be mapped at all times, so we allocate that
* part of the Guest page table here.
*/
int init_guest_pagetable(struct lguest *lg)
{
@ -971,21 +1036,34 @@ int init_guest_pagetable(struct lguest *lg)
/* We start with a linear mapping until the initialize. */
cpu->linear_pages = true;
/* Allocate the page tables for the Switcher. */
if (!allocate_switcher_mapping(cpu)) {
release_all_pagetables(lg);
return -ENOMEM;
}
return 0;
}
/*H:508 When the Guest calls LHCALL_LGUEST_INIT we do more setup. */
void page_table_guest_data_init(struct lg_cpu *cpu)
{
/*
* We tell the Guest that it can't use the virtual addresses
* used by the Switcher. This trick is equivalent to 4GB -
* switcher_addr.
*/
u32 top = ~switcher_addr + 1;
/* We get the kernel address: above this is all kernel memory. */
if (get_user(cpu->lg->kernel_address,
&cpu->lg->lguest_data->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.
* We tell the Guest that it can't use the top virtual
* addresses (used by the Switcher).
*/
|| put_user(RESERVE_MEM * 1024 * 1024,
&cpu->lg->lguest_data->reserve_mem)) {
|| put_user(top, &cpu->lg->lguest_data->reserve_mem)) {
kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data);
return;
}
@ -995,12 +1073,7 @@ void page_table_guest_data_init(struct lg_cpu *cpu)
* "pgd_index(lg->kernel_address)". This assumes it won't hit the
* 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
if (cpu->lg->kernel_address >= switcher_addr)
kill_guest(cpu, "bad kernel address %#lx",
cpu->lg->kernel_address);
}
@ -1017,102 +1090,96 @@ void free_guest_pagetable(struct lguest *lg)
free_page((long)lg->pgdirs[i].pgdir);
}
/*H:481
* This clears the Switcher mappings for cpu #i.
*/
static void remove_switcher_percpu_map(struct lg_cpu *cpu, unsigned int i)
{
unsigned long base = switcher_addr + PAGE_SIZE + i * PAGE_SIZE*2;
pte_t *pte;
/* Clear the mappings for both pages. */
pte = find_spte(cpu, base, false, 0, 0);
release_pte(*pte);
set_pte(pte, __pte(0));
pte = find_spte(cpu, base + PAGE_SIZE, false, 0, 0);
release_pte(*pte);
set_pte(pte, __pte(0));
}
/*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.
* The Switcher and the two pages for this CPU need to be visible in the Guest
* (and not the pages for other CPUs).
*
* The pages for the pagetables have all been allocated before: we just need
* to make sure the actual PTEs are up-to-date for the CPU we're about to run
* on.
*/
void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages)
{
pte_t *switcher_pte_page = __this_cpu_read(switcher_pte_pages);
pte_t regs_pte;
unsigned long base;
struct page *percpu_switcher_page, *regs_page;
pte_t *pte;
struct pgdir *pgdir = &cpu->lg->pgdirs[cpu->cpu_pgd];
#ifdef CONFIG_X86_PAE
pmd_t switcher_pmd;
pmd_t *pmd_table;
/* Switcher page should always be mapped by now! */
BUG_ON(!pgdir->switcher_mapped);
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).
/*
* Remember that we have two pages for each Host CPU, so we can run a
* Guest on each CPU without them interfering. We need to make sure
* those pages are mapped correctly in the Guest, but since we usually
* run on the same CPU, we cache that, and only update the mappings
* when we move.
*/
switcher_pgd = __pgd(__pa(switcher_pte_page) | __PAGE_KERNEL_EXEC);
if (pgdir->last_host_cpu == raw_smp_processor_id())
return;
cpu->lg->pgdirs[cpu->cpu_pgd].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd;
#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(cpu->regs_page) >> PAGE_SHIFT, PAGE_KERNEL);
set_pte(&switcher_pte_page[pte_index((unsigned long)pages)], regs_pte);
}
/*:*/
static void free_switcher_pte_pages(void)
{
unsigned int i;
for_each_possible_cpu(i)
free_page((long)switcher_pte_page(i));
}
/*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.
*/
static __init void populate_switcher_pte_page(unsigned int cpu,
struct page *switcher_page[],
unsigned int pages)
{
unsigned int i;
pte_t *pte = switcher_pte_page(cpu);
/* The first entries are easy: they map the Switcher code. */
for (i = 0; i < pages; i++) {
set_pte(&pte[i], mk_pte(switcher_page[i],
__pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));
/* -1 means unknown so we remove everything. */
if (pgdir->last_host_cpu == -1) {
unsigned int i;
for_each_possible_cpu(i)
remove_switcher_percpu_map(cpu, i);
} else {
/* We know exactly what CPU mapping to remove. */
remove_switcher_percpu_map(cpu, pgdir->last_host_cpu);
}
/* 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 */
set_pte(&pte[i], pfn_pte(page_to_pfn(switcher_page[i]),
__pgprot(_PAGE_PRESENT|_PAGE_ACCESSED|_PAGE_RW)));
/*
* 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.
*/
/* Find the shadow PTE for this regs page. */
base = switcher_addr + PAGE_SIZE
+ raw_smp_processor_id() * sizeof(struct lguest_pages);
pte = find_spte(cpu, base, false, 0, 0);
regs_page = pfn_to_page(__pa(cpu->regs_page) >> PAGE_SHIFT);
get_page(regs_page);
set_pte(pte, mk_pte(regs_page, __pgprot(__PAGE_KERNEL & ~_PAGE_GLOBAL)));
/*
* The second page contains the "struct lguest_ro_state", and is
* read-only.
* We map the second page of the struct lguest_pages read-only in
* the Guest: the IDT, GDT and other things it's not supposed to
* change.
*/
set_pte(&pte[i+1], pfn_pte(page_to_pfn(switcher_page[i+1]),
__pgprot(_PAGE_PRESENT|_PAGE_ACCESSED)));
pte = find_spte(cpu, base + PAGE_SIZE, false, 0, 0);
percpu_switcher_page
= lg_switcher_pages[1 + raw_smp_processor_id()*2 + 1];
get_page(percpu_switcher_page);
set_pte(pte, mk_pte(percpu_switcher_page,
__pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL)));
pgdir->last_host_cpu = raw_smp_processor_id();
}
/*
/*H:490
* 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.
*
@ -1124,29 +1191,3 @@ static __init void populate_switcher_pte_page(unsigned int cpu,
*
* 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.
*/
__init int init_pagetables(struct page **switcher_page, unsigned int pages)
{
unsigned int i;
for_each_possible_cpu(i) {
switcher_pte_page(i) = (pte_t *)get_zeroed_page(GFP_KERNEL);
if (!switcher_pte_page(i)) {
free_switcher_pte_pages();
return -ENOMEM;
}
populate_switcher_pte_page(i, switcher_page, pages);
}
return 0;
}
/*:*/
/* Cleaning up simply involves freeing the PTE page for each CPU. */
void free_pagetables(void)
{
free_switcher_pte_pages();
}

7
drivers/lguest/x86/core.c
View file

@ -59,14 +59,13 @@ static struct {
/* Offset from where switcher.S was compiled to where we've copied it */
static unsigned long switcher_offset(void)
{
return SWITCHER_ADDR - (unsigned long)start_switcher_text;
return switcher_addr - (unsigned long)start_switcher_text;
}
/* This cpu's struct lguest_pages. */
/* This cpu's struct lguest_pages (after the Switcher text page) */
static struct lguest_pages *lguest_pages(unsigned int cpu)
{
return &(((struct lguest_pages *)
(SWITCHER_ADDR + SHARED_SWITCHER_PAGES*PAGE_SIZE))[cpu]);
return &(((struct lguest_pages *)(switcher_addr + PAGE_SIZE))[cpu]);
}
static DEFINE_PER_CPU(struct lg_cpu *, lg_last_cpu);