linux/arch/x86/xen/p2m.c
Michal Hocko 32d6bd9059 tree wide: get rid of __GFP_REPEAT for order-0 allocations part I
This is the third version of the patchset previously sent [1].  I have
basically only rebased it on top of 4.7-rc1 tree and dropped "dm: get
rid of superfluous gfp flags" which went through dm tree.  I am sending
it now because it is tree wide and chances for conflicts are reduced
considerably when we want to target rc2.  I plan to send the next step
and rename the flag and move to a better semantic later during this
release cycle so we will have a new semantic ready for 4.8 merge window
hopefully.

Motivation:

While working on something unrelated I've checked the current usage of
__GFP_REPEAT in the tree.  It seems that a majority of the usage is and
always has been bogus because __GFP_REPEAT has always been about costly
high order allocations while we are using it for order-0 or very small
orders very often.  It seems that a big pile of them is just a
copy&paste when a code has been adopted from one arch to another.

I think it makes some sense to get rid of them because they are just
making the semantic more unclear.  Please note that GFP_REPEAT is
documented as

* __GFP_REPEAT: Try hard to allocate the memory, but the allocation attempt

* _might_ fail.  This depends upon the particular VM implementation.
  while !costly requests have basically nofail semantic.  So one could
  reasonably expect that order-0 request with __GFP_REPEAT will not loop
  for ever.  This is not implemented right now though.

I would like to move on with __GFP_REPEAT and define a better semantic
for it.

  $ git grep __GFP_REPEAT origin/master | wc -l
  111
  $ git grep __GFP_REPEAT | wc -l
  36

So we are down to the third after this patch series.  The remaining
places really seem to be relying on __GFP_REPEAT due to large allocation
requests.  This still needs some double checking which I will do later
after all the simple ones are sorted out.

I am touching a lot of arch specific code here and I hope I got it right
but as a matter of fact I even didn't compile test for some archs as I
do not have cross compiler for them.  Patches should be quite trivial to
review for stupid compile mistakes though.  The tricky parts are usually
hidden by macro definitions and thats where I would appreciate help from
arch maintainers.

[1] http://lkml.kernel.org/r/1461849846-27209-1-git-send-email-mhocko@kernel.org

This patch (of 19):

__GFP_REPEAT has a rather weak semantic but since it has been introduced
around 2.6.12 it has been ignored for low order allocations.  Yet we
have the full kernel tree with its usage for apparently order-0
allocations.  This is really confusing because __GFP_REPEAT is
explicitly documented to allow allocation failures which is a weaker
semantic than the current order-0 has (basically nofail).

Let's simply drop __GFP_REPEAT from those places.  This would allow to
identify place which really need allocator to retry harder and formulate
a more specific semantic for what the flag is supposed to do actually.

Link: http://lkml.kernel.org/r/1464599699-30131-2-git-send-email-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chen Liqin <liqin.linux@gmail.com>
Cc: Chris Metcalf <cmetcalf@mellanox.com> [for tile]
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jan Kara <jack@suse.cz>
Cc: John Crispin <blogic@openwrt.org>
Cc: Lennox Wu <lennox.wu@gmail.com>
Cc: Ley Foon Tan <lftan@altera.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-06-24 17:23:52 -07:00

839 lines
22 KiB
C

/*
* Xen leaves the responsibility for maintaining p2m mappings to the
* guests themselves, but it must also access and update the p2m array
* during suspend/resume when all the pages are reallocated.
*
* The logical flat p2m table is mapped to a linear kernel memory area.
* For accesses by Xen a three-level tree linked via mfns only is set up to
* allow the address space to be sparse.
*
* Xen
* |
* p2m_top_mfn
* / \
* p2m_mid_mfn p2m_mid_mfn
* / /
* p2m p2m p2m ...
*
* The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
*
* The p2m_top_mfn level is limited to 1 page, so the maximum representable
* pseudo-physical address space is:
* P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE pages
*
* P2M_PER_PAGE depends on the architecture, as a mfn is always
* unsigned long (8 bytes on 64-bit, 4 bytes on 32), leading to
* 512 and 1024 entries respectively.
*
* In short, these structures contain the Machine Frame Number (MFN) of the PFN.
*
* However not all entries are filled with MFNs. Specifically for all other
* leaf entries, or for the top root, or middle one, for which there is a void
* entry, we assume it is "missing". So (for example)
* pfn_to_mfn(0x90909090)=INVALID_P2M_ENTRY.
* We have a dedicated page p2m_missing with all entries being
* INVALID_P2M_ENTRY. This page may be referenced multiple times in the p2m
* list/tree in case there are multiple areas with P2M_PER_PAGE invalid pfns.
*
* We also have the possibility of setting 1-1 mappings on certain regions, so
* that:
* pfn_to_mfn(0xc0000)=0xc0000
*
* The benefit of this is, that we can assume for non-RAM regions (think
* PCI BARs, or ACPI spaces), we can create mappings easily because we
* get the PFN value to match the MFN.
*
* For this to work efficiently we have one new page p2m_identity. All entries
* in p2m_identity are set to INVALID_P2M_ENTRY type (Xen toolstack only
* recognizes that and MFNs, no other fancy value).
*
* On lookup we spot that the entry points to p2m_identity and return the
* identity value instead of dereferencing and returning INVALID_P2M_ENTRY.
* If the entry points to an allocated page, we just proceed as before and
* return the PFN. If the PFN has IDENTITY_FRAME_BIT set we unmask that in
* appropriate functions (pfn_to_mfn).
*
* The reason for having the IDENTITY_FRAME_BIT instead of just returning the
* PFN is that we could find ourselves where pfn_to_mfn(pfn)==pfn for a
* non-identity pfn. To protect ourselves against we elect to set (and get) the
* IDENTITY_FRAME_BIT on all identity mapped PFNs.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/list.h>
#include <linux/hash.h>
#include <linux/sched.h>
#include <linux/seq_file.h>
#include <linux/bootmem.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <asm/cache.h>
#include <asm/setup.h>
#include <asm/uaccess.h>
#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <xen/balloon.h>
#include <xen/grant_table.h>
#include "multicalls.h"
#include "xen-ops.h"
#define P2M_MID_PER_PAGE (PAGE_SIZE / sizeof(unsigned long *))
#define P2M_TOP_PER_PAGE (PAGE_SIZE / sizeof(unsigned long **))
#define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE)
#define PMDS_PER_MID_PAGE (P2M_MID_PER_PAGE / PTRS_PER_PTE)
unsigned long *xen_p2m_addr __read_mostly;
EXPORT_SYMBOL_GPL(xen_p2m_addr);
unsigned long xen_p2m_size __read_mostly;
EXPORT_SYMBOL_GPL(xen_p2m_size);
unsigned long xen_max_p2m_pfn __read_mostly;
EXPORT_SYMBOL_GPL(xen_max_p2m_pfn);
#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
#define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
#else
#define P2M_LIMIT 0
#endif
static DEFINE_SPINLOCK(p2m_update_lock);
static unsigned long *p2m_mid_missing_mfn;
static unsigned long *p2m_top_mfn;
static unsigned long **p2m_top_mfn_p;
static unsigned long *p2m_missing;
static unsigned long *p2m_identity;
static pte_t *p2m_missing_pte;
static pte_t *p2m_identity_pte;
/*
* Hint at last populated PFN.
*
* Used to set HYPERVISOR_shared_info->arch.max_pfn so the toolstack
* can avoid scanning the whole P2M (which may be sized to account for
* hotplugged memory).
*/
static unsigned long xen_p2m_last_pfn;
static inline unsigned p2m_top_index(unsigned long pfn)
{
BUG_ON(pfn >= MAX_P2M_PFN);
return pfn / (P2M_MID_PER_PAGE * P2M_PER_PAGE);
}
static inline unsigned p2m_mid_index(unsigned long pfn)
{
return (pfn / P2M_PER_PAGE) % P2M_MID_PER_PAGE;
}
static inline unsigned p2m_index(unsigned long pfn)
{
return pfn % P2M_PER_PAGE;
}
static void p2m_top_mfn_init(unsigned long *top)
{
unsigned i;
for (i = 0; i < P2M_TOP_PER_PAGE; i++)
top[i] = virt_to_mfn(p2m_mid_missing_mfn);
}
static void p2m_top_mfn_p_init(unsigned long **top)
{
unsigned i;
for (i = 0; i < P2M_TOP_PER_PAGE; i++)
top[i] = p2m_mid_missing_mfn;
}
static void p2m_mid_mfn_init(unsigned long *mid, unsigned long *leaf)
{
unsigned i;
for (i = 0; i < P2M_MID_PER_PAGE; i++)
mid[i] = virt_to_mfn(leaf);
}
static void p2m_init(unsigned long *p2m)
{
unsigned i;
for (i = 0; i < P2M_PER_PAGE; i++)
p2m[i] = INVALID_P2M_ENTRY;
}
static void p2m_init_identity(unsigned long *p2m, unsigned long pfn)
{
unsigned i;
for (i = 0; i < P2M_PER_PAGE; i++)
p2m[i] = IDENTITY_FRAME(pfn + i);
}
static void * __ref alloc_p2m_page(void)
{
if (unlikely(!slab_is_available()))
return alloc_bootmem_align(PAGE_SIZE, PAGE_SIZE);
return (void *)__get_free_page(GFP_KERNEL);
}
static void __ref free_p2m_page(void *p)
{
if (unlikely(!slab_is_available())) {
free_bootmem((unsigned long)p, PAGE_SIZE);
return;
}
free_page((unsigned long)p);
}
/*
* Build the parallel p2m_top_mfn and p2m_mid_mfn structures
*
* This is called both at boot time, and after resuming from suspend:
* - At boot time we're called rather early, and must use alloc_bootmem*()
* to allocate memory.
*
* - After resume we're called from within stop_machine, but the mfn
* tree should already be completely allocated.
*/
void __ref xen_build_mfn_list_list(void)
{
unsigned long pfn, mfn;
pte_t *ptep;
unsigned int level, topidx, mididx;
unsigned long *mid_mfn_p;
if (xen_feature(XENFEAT_auto_translated_physmap) ||
xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
return;
/* Pre-initialize p2m_top_mfn to be completely missing */
if (p2m_top_mfn == NULL) {
p2m_mid_missing_mfn = alloc_p2m_page();
p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
p2m_top_mfn_p = alloc_p2m_page();
p2m_top_mfn_p_init(p2m_top_mfn_p);
p2m_top_mfn = alloc_p2m_page();
p2m_top_mfn_init(p2m_top_mfn);
} else {
/* Reinitialise, mfn's all change after migration */
p2m_mid_mfn_init(p2m_mid_missing_mfn, p2m_missing);
}
for (pfn = 0; pfn < xen_max_p2m_pfn && pfn < MAX_P2M_PFN;
pfn += P2M_PER_PAGE) {
topidx = p2m_top_index(pfn);
mididx = p2m_mid_index(pfn);
mid_mfn_p = p2m_top_mfn_p[topidx];
ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn),
&level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
mfn = pte_mfn(*ptep);
ptep = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
/* Don't bother allocating any mfn mid levels if
* they're just missing, just update the stored mfn,
* since all could have changed over a migrate.
*/
if (ptep == p2m_missing_pte || ptep == p2m_identity_pte) {
BUG_ON(mididx);
BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
p2m_top_mfn[topidx] = virt_to_mfn(p2m_mid_missing_mfn);
pfn += (P2M_MID_PER_PAGE - 1) * P2M_PER_PAGE;
continue;
}
if (mid_mfn_p == p2m_mid_missing_mfn) {
mid_mfn_p = alloc_p2m_page();
p2m_mid_mfn_init(mid_mfn_p, p2m_missing);
p2m_top_mfn_p[topidx] = mid_mfn_p;
}
p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
mid_mfn_p[mididx] = mfn;
}
}
void xen_setup_mfn_list_list(void)
{
if (xen_feature(XENFEAT_auto_translated_physmap))
return;
BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
if (xen_start_info->flags & SIF_VIRT_P2M_4TOOLS)
HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list = ~0UL;
else
HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
virt_to_mfn(p2m_top_mfn);
HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
HYPERVISOR_shared_info->arch.p2m_generation = 0;
HYPERVISOR_shared_info->arch.p2m_vaddr = (unsigned long)xen_p2m_addr;
HYPERVISOR_shared_info->arch.p2m_cr3 =
xen_pfn_to_cr3(virt_to_mfn(swapper_pg_dir));
}
/* Set up p2m_top to point to the domain-builder provided p2m pages */
void __init xen_build_dynamic_phys_to_machine(void)
{
unsigned long pfn;
if (xen_feature(XENFEAT_auto_translated_physmap))
return;
xen_p2m_addr = (unsigned long *)xen_start_info->mfn_list;
xen_p2m_size = ALIGN(xen_start_info->nr_pages, P2M_PER_PAGE);
for (pfn = xen_start_info->nr_pages; pfn < xen_p2m_size; pfn++)
xen_p2m_addr[pfn] = INVALID_P2M_ENTRY;
xen_max_p2m_pfn = xen_p2m_size;
}
#define P2M_TYPE_IDENTITY 0
#define P2M_TYPE_MISSING 1
#define P2M_TYPE_PFN 2
#define P2M_TYPE_UNKNOWN 3
static int xen_p2m_elem_type(unsigned long pfn)
{
unsigned long mfn;
if (pfn >= xen_p2m_size)
return P2M_TYPE_IDENTITY;
mfn = xen_p2m_addr[pfn];
if (mfn == INVALID_P2M_ENTRY)
return P2M_TYPE_MISSING;
if (mfn & IDENTITY_FRAME_BIT)
return P2M_TYPE_IDENTITY;
return P2M_TYPE_PFN;
}
static void __init xen_rebuild_p2m_list(unsigned long *p2m)
{
unsigned int i, chunk;
unsigned long pfn;
unsigned long *mfns;
pte_t *ptep;
pmd_t *pmdp;
int type;
p2m_missing = alloc_p2m_page();
p2m_init(p2m_missing);
p2m_identity = alloc_p2m_page();
p2m_init(p2m_identity);
p2m_missing_pte = alloc_p2m_page();
paravirt_alloc_pte(&init_mm, __pa(p2m_missing_pte) >> PAGE_SHIFT);
p2m_identity_pte = alloc_p2m_page();
paravirt_alloc_pte(&init_mm, __pa(p2m_identity_pte) >> PAGE_SHIFT);
for (i = 0; i < PTRS_PER_PTE; i++) {
set_pte(p2m_missing_pte + i,
pfn_pte(PFN_DOWN(__pa(p2m_missing)), PAGE_KERNEL_RO));
set_pte(p2m_identity_pte + i,
pfn_pte(PFN_DOWN(__pa(p2m_identity)), PAGE_KERNEL_RO));
}
for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += chunk) {
/*
* Try to map missing/identity PMDs or p2m-pages if possible.
* We have to respect the structure of the mfn_list_list
* which will be built just afterwards.
* Chunk size to test is one p2m page if we are in the middle
* of a mfn_list_list mid page and the complete mid page area
* if we are at index 0 of the mid page. Please note that a
* mid page might cover more than one PMD, e.g. on 32 bit PAE
* kernels.
*/
chunk = (pfn & (P2M_PER_PAGE * P2M_MID_PER_PAGE - 1)) ?
P2M_PER_PAGE : P2M_PER_PAGE * P2M_MID_PER_PAGE;
type = xen_p2m_elem_type(pfn);
i = 0;
if (type != P2M_TYPE_PFN)
for (i = 1; i < chunk; i++)
if (xen_p2m_elem_type(pfn + i) != type)
break;
if (i < chunk)
/* Reset to minimal chunk size. */
chunk = P2M_PER_PAGE;
if (type == P2M_TYPE_PFN || i < chunk) {
/* Use initial p2m page contents. */
#ifdef CONFIG_X86_64
mfns = alloc_p2m_page();
copy_page(mfns, xen_p2m_addr + pfn);
#else
mfns = xen_p2m_addr + pfn;
#endif
ptep = populate_extra_pte((unsigned long)(p2m + pfn));
set_pte(ptep,
pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL));
continue;
}
if (chunk == P2M_PER_PAGE) {
/* Map complete missing or identity p2m-page. */
mfns = (type == P2M_TYPE_MISSING) ?
p2m_missing : p2m_identity;
ptep = populate_extra_pte((unsigned long)(p2m + pfn));
set_pte(ptep,
pfn_pte(PFN_DOWN(__pa(mfns)), PAGE_KERNEL_RO));
continue;
}
/* Complete missing or identity PMD(s) can be mapped. */
ptep = (type == P2M_TYPE_MISSING) ?
p2m_missing_pte : p2m_identity_pte;
for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
pmdp = populate_extra_pmd(
(unsigned long)(p2m + pfn) + i * PMD_SIZE);
set_pmd(pmdp, __pmd(__pa(ptep) | _KERNPG_TABLE));
}
}
}
void __init xen_vmalloc_p2m_tree(void)
{
static struct vm_struct vm;
unsigned long p2m_limit;
xen_p2m_last_pfn = xen_max_p2m_pfn;
p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE;
vm.flags = VM_ALLOC;
vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit),
PMD_SIZE * PMDS_PER_MID_PAGE);
vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE);
pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size);
xen_max_p2m_pfn = vm.size / sizeof(unsigned long);
xen_rebuild_p2m_list(vm.addr);
xen_p2m_addr = vm.addr;
xen_p2m_size = xen_max_p2m_pfn;
xen_inv_extra_mem();
}
unsigned long get_phys_to_machine(unsigned long pfn)
{
pte_t *ptep;
unsigned int level;
if (unlikely(pfn >= xen_p2m_size)) {
if (pfn < xen_max_p2m_pfn)
return xen_chk_extra_mem(pfn);
return IDENTITY_FRAME(pfn);
}
ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
/*
* The INVALID_P2M_ENTRY is filled in both p2m_*identity
* and in p2m_*missing, so returning the INVALID_P2M_ENTRY
* would be wrong.
*/
if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
return IDENTITY_FRAME(pfn);
return xen_p2m_addr[pfn];
}
EXPORT_SYMBOL_GPL(get_phys_to_machine);
/*
* Allocate new pmd(s). It is checked whether the old pmd is still in place.
* If not, nothing is changed. This is okay as the only reason for allocating
* a new pmd is to replace p2m_missing_pte or p2m_identity_pte by a individual
* pmd. In case of PAE/x86-32 there are multiple pmds to allocate!
*/
static pte_t *alloc_p2m_pmd(unsigned long addr, pte_t *pte_pg)
{
pte_t *ptechk;
pte_t *pte_newpg[PMDS_PER_MID_PAGE];
pmd_t *pmdp;
unsigned int level;
unsigned long flags;
unsigned long vaddr;
int i;
/* Do all allocations first to bail out in error case. */
for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
pte_newpg[i] = alloc_p2m_page();
if (!pte_newpg[i]) {
for (i--; i >= 0; i--)
free_p2m_page(pte_newpg[i]);
return NULL;
}
}
vaddr = addr & ~(PMD_SIZE * PMDS_PER_MID_PAGE - 1);
for (i = 0; i < PMDS_PER_MID_PAGE; i++) {
copy_page(pte_newpg[i], pte_pg);
paravirt_alloc_pte(&init_mm, __pa(pte_newpg[i]) >> PAGE_SHIFT);
pmdp = lookup_pmd_address(vaddr);
BUG_ON(!pmdp);
spin_lock_irqsave(&p2m_update_lock, flags);
ptechk = lookup_address(vaddr, &level);
if (ptechk == pte_pg) {
HYPERVISOR_shared_info->arch.p2m_generation++;
wmb(); /* Tools are synchronizing via p2m_generation. */
set_pmd(pmdp,
__pmd(__pa(pte_newpg[i]) | _KERNPG_TABLE));
wmb(); /* Tools are synchronizing via p2m_generation. */
HYPERVISOR_shared_info->arch.p2m_generation++;
pte_newpg[i] = NULL;
}
spin_unlock_irqrestore(&p2m_update_lock, flags);
if (pte_newpg[i]) {
paravirt_release_pte(__pa(pte_newpg[i]) >> PAGE_SHIFT);
free_p2m_page(pte_newpg[i]);
}
vaddr += PMD_SIZE;
}
return lookup_address(addr, &level);
}
/*
* Fully allocate the p2m structure for a given pfn. We need to check
* that both the top and mid levels are allocated, and make sure the
* parallel mfn tree is kept in sync. We may race with other cpus, so
* the new pages are installed with cmpxchg; if we lose the race then
* simply free the page we allocated and use the one that's there.
*/
int xen_alloc_p2m_entry(unsigned long pfn)
{
unsigned topidx;
unsigned long *top_mfn_p, *mid_mfn;
pte_t *ptep, *pte_pg;
unsigned int level;
unsigned long flags;
unsigned long addr = (unsigned long)(xen_p2m_addr + pfn);
unsigned long p2m_pfn;
if (xen_feature(XENFEAT_auto_translated_physmap))
return 0;
ptep = lookup_address(addr, &level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
pte_pg = (pte_t *)((unsigned long)ptep & ~(PAGE_SIZE - 1));
if (pte_pg == p2m_missing_pte || pte_pg == p2m_identity_pte) {
/* PMD level is missing, allocate a new one */
ptep = alloc_p2m_pmd(addr, pte_pg);
if (!ptep)
return -ENOMEM;
}
if (p2m_top_mfn && pfn < MAX_P2M_PFN) {
topidx = p2m_top_index(pfn);
top_mfn_p = &p2m_top_mfn[topidx];
mid_mfn = ACCESS_ONCE(p2m_top_mfn_p[topidx]);
BUG_ON(virt_to_mfn(mid_mfn) != *top_mfn_p);
if (mid_mfn == p2m_mid_missing_mfn) {
/* Separately check the mid mfn level */
unsigned long missing_mfn;
unsigned long mid_mfn_mfn;
unsigned long old_mfn;
mid_mfn = alloc_p2m_page();
if (!mid_mfn)
return -ENOMEM;
p2m_mid_mfn_init(mid_mfn, p2m_missing);
missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
mid_mfn_mfn = virt_to_mfn(mid_mfn);
old_mfn = cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn);
if (old_mfn != missing_mfn) {
free_p2m_page(mid_mfn);
mid_mfn = mfn_to_virt(old_mfn);
} else {
p2m_top_mfn_p[topidx] = mid_mfn;
}
}
} else {
mid_mfn = NULL;
}
p2m_pfn = pte_pfn(READ_ONCE(*ptep));
if (p2m_pfn == PFN_DOWN(__pa(p2m_identity)) ||
p2m_pfn == PFN_DOWN(__pa(p2m_missing))) {
/* p2m leaf page is missing */
unsigned long *p2m;
p2m = alloc_p2m_page();
if (!p2m)
return -ENOMEM;
if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
p2m_init(p2m);
else
p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
spin_lock_irqsave(&p2m_update_lock, flags);
if (pte_pfn(*ptep) == p2m_pfn) {
HYPERVISOR_shared_info->arch.p2m_generation++;
wmb(); /* Tools are synchronizing via p2m_generation. */
set_pte(ptep,
pfn_pte(PFN_DOWN(__pa(p2m)), PAGE_KERNEL));
wmb(); /* Tools are synchronizing via p2m_generation. */
HYPERVISOR_shared_info->arch.p2m_generation++;
if (mid_mfn)
mid_mfn[p2m_mid_index(pfn)] = virt_to_mfn(p2m);
p2m = NULL;
}
spin_unlock_irqrestore(&p2m_update_lock, flags);
if (p2m)
free_p2m_page(p2m);
}
/* Expanded the p2m? */
if (pfn > xen_p2m_last_pfn) {
xen_p2m_last_pfn = pfn;
HYPERVISOR_shared_info->arch.max_pfn = xen_p2m_last_pfn;
}
return 0;
}
EXPORT_SYMBOL(xen_alloc_p2m_entry);
unsigned long __init set_phys_range_identity(unsigned long pfn_s,
unsigned long pfn_e)
{
unsigned long pfn;
if (unlikely(pfn_s >= xen_p2m_size))
return 0;
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
return pfn_e - pfn_s;
if (pfn_s > pfn_e)
return 0;
if (pfn_e > xen_p2m_size)
pfn_e = xen_p2m_size;
for (pfn = pfn_s; pfn < pfn_e; pfn++)
xen_p2m_addr[pfn] = IDENTITY_FRAME(pfn);
return pfn - pfn_s;
}
bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
pte_t *ptep;
unsigned int level;
/* don't track P2M changes in autotranslate guests */
if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
return true;
if (unlikely(pfn >= xen_p2m_size)) {
BUG_ON(mfn != INVALID_P2M_ENTRY);
return true;
}
/*
* The interface requires atomic updates on p2m elements.
* xen_safe_write_ulong() is using __put_user which does an atomic
* store via asm().
*/
if (likely(!xen_safe_write_ulong(xen_p2m_addr + pfn, mfn)))
return true;
ptep = lookup_address((unsigned long)(xen_p2m_addr + pfn), &level);
BUG_ON(!ptep || level != PG_LEVEL_4K);
if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_missing)))
return mfn == INVALID_P2M_ENTRY;
if (pte_pfn(*ptep) == PFN_DOWN(__pa(p2m_identity)))
return mfn == IDENTITY_FRAME(pfn);
return false;
}
bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
{
if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
int ret;
ret = xen_alloc_p2m_entry(pfn);
if (ret < 0)
return false;
return __set_phys_to_machine(pfn, mfn);
}
return true;
}
int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret = 0;
pte_t *pte;
if (xen_feature(XENFEAT_auto_translated_physmap))
return 0;
if (kmap_ops) {
ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
kmap_ops, count);
if (ret)
goto out;
}
for (i = 0; i < count; i++) {
unsigned long mfn, pfn;
/* Do not add to override if the map failed. */
if (map_ops[i].status)
continue;
if (map_ops[i].flags & GNTMAP_contains_pte) {
pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
(map_ops[i].host_addr & ~PAGE_MASK));
mfn = pte_mfn(*pte);
} else {
mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
}
pfn = page_to_pfn(pages[i]);
WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
ret = -ENOMEM;
goto out;
}
}
out:
return ret;
}
EXPORT_SYMBOL_GPL(set_foreign_p2m_mapping);
int clear_foreign_p2m_mapping(struct gnttab_unmap_grant_ref *unmap_ops,
struct gnttab_unmap_grant_ref *kunmap_ops,
struct page **pages, unsigned int count)
{
int i, ret = 0;
if (xen_feature(XENFEAT_auto_translated_physmap))
return 0;
for (i = 0; i < count; i++) {
unsigned long mfn = __pfn_to_mfn(page_to_pfn(pages[i]));
unsigned long pfn = page_to_pfn(pages[i]);
if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT)) {
ret = -EINVAL;
goto out;
}
set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
}
if (kunmap_ops)
ret = HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref,
kunmap_ops, count);
out:
return ret;
}
EXPORT_SYMBOL_GPL(clear_foreign_p2m_mapping);
#ifdef CONFIG_XEN_DEBUG_FS
#include <linux/debugfs.h>
#include "debugfs.h"
static int p2m_dump_show(struct seq_file *m, void *v)
{
static const char * const type_name[] = {
[P2M_TYPE_IDENTITY] = "identity",
[P2M_TYPE_MISSING] = "missing",
[P2M_TYPE_PFN] = "pfn",
[P2M_TYPE_UNKNOWN] = "abnormal"};
unsigned long pfn, first_pfn;
int type, prev_type;
prev_type = xen_p2m_elem_type(0);
first_pfn = 0;
for (pfn = 0; pfn < xen_p2m_size; pfn++) {
type = xen_p2m_elem_type(pfn);
if (type != prev_type) {
seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
type_name[prev_type]);
prev_type = type;
first_pfn = pfn;
}
}
seq_printf(m, " [0x%lx->0x%lx] %s\n", first_pfn, pfn,
type_name[prev_type]);
return 0;
}
static int p2m_dump_open(struct inode *inode, struct file *filp)
{
return single_open(filp, p2m_dump_show, NULL);
}
static const struct file_operations p2m_dump_fops = {
.open = p2m_dump_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static struct dentry *d_mmu_debug;
static int __init xen_p2m_debugfs(void)
{
struct dentry *d_xen = xen_init_debugfs();
if (d_xen == NULL)
return -ENOMEM;
d_mmu_debug = debugfs_create_dir("mmu", d_xen);
debugfs_create_file("p2m", 0600, d_mmu_debug, NULL, &p2m_dump_fops);
return 0;
}
fs_initcall(xen_p2m_debugfs);
#endif /* CONFIG_XEN_DEBUG_FS */