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authorAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
committerAnton Arapov <anton@redhat.com>2012-04-16 10:05:28 +0200
commitb4b6116a13633898cf868f2f103c96a90c4c20f8 (patch)
tree93d1b7e2cfcdf473d8d4ff3ad141fa864f8491f6 /arch/x86/xen/p2m.c
parentedd4be777c953e5faafc80d091d3084b4343f5d3 (diff)
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fedora kernel: d9aad82f3319f3cfd1aebc01234254ef0c37ad84v3.3.2-1
Signed-off-by: Anton Arapov <anton@redhat.com>
Diffstat (limited to 'arch/x86/xen/p2m.c')
-rw-r--r--arch/x86/xen/p2m.c949
1 files changed, 949 insertions, 0 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
new file mode 100644
index 00000000000..1b267e75158
--- /dev/null
+++ b/arch/x86/xen/p2m.c
@@ -0,0 +1,949 @@
+/*
+ * 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 p2m table is logically a flat array, but we implement it as a
+ * three-level tree to allow the address space to be sparse.
+ *
+ * Xen
+ * |
+ * p2m_top p2m_top_mfn
+ * / \ / \
+ * p2m_mid p2m_mid p2m_mid_mfn p2m_mid_mfn
+ * / \ / \ / /
+ * p2m p2m p2m p2m p2m p2m p2m ...
+ *
+ * The p2m_mid_mfn pages are mapped by p2m_top_mfn_p.
+ *
+ * The p2m_top and p2m_top_mfn levels are 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 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 b/c we
+ * get the PFN value to match the MFN.
+ *
+ * For this to work efficiently we have one new page p2m_identity and
+ * allocate (via reserved_brk) any other pages we need to cover the sides
+ * (1GB or 4MB boundary violations). 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.
+ *
+ * This simplistic diagram is used to explain the more subtle piece of code.
+ * There is also a digram of the P2M at the end that can help.
+ * Imagine your E820 looking as so:
+ *
+ * 1GB 2GB
+ * /-------------------+---------\/----\ /----------\ /---+-----\
+ * | System RAM | Sys RAM ||ACPI| | reserved | | Sys RAM |
+ * \-------------------+---------/\----/ \----------/ \---+-----/
+ * ^- 1029MB ^- 2001MB
+ *
+ * [1029MB = 263424 (0x40500), 2001MB = 512256 (0x7D100),
+ * 2048MB = 524288 (0x80000)]
+ *
+ * And dom0_mem=max:3GB,1GB is passed in to the guest, meaning memory past 1GB
+ * is actually not present (would have to kick the balloon driver to put it in).
+ *
+ * When we are told to set the PFNs for identity mapping (see patch: "xen/setup:
+ * Set identity mapping for non-RAM E820 and E820 gaps.") we pass in the start
+ * of the PFN and the end PFN (263424 and 512256 respectively). The first step
+ * is to reserve_brk a top leaf page if the p2m[1] is missing. The top leaf page
+ * covers 512^2 of page estate (1GB) and in case the start or end PFN is not
+ * aligned on 512^2*PAGE_SIZE (1GB) we loop on aligned 1GB PFNs from start pfn
+ * to end pfn. We reserve_brk top leaf pages if they are missing (means they
+ * point to p2m_mid_missing).
+ *
+ * With the E820 example above, 263424 is not 1GB aligned so we allocate a
+ * reserve_brk page which will cover the PFNs estate from 0x40000 to 0x80000.
+ * Each entry in the allocate page is "missing" (points to p2m_missing).
+ *
+ * Next stage is to determine if we need to do a more granular boundary check
+ * on the 4MB (or 2MB depending on architecture) off the start and end pfn's.
+ * We check if the start pfn and end pfn violate that boundary check, and if
+ * so reserve_brk a middle (p2m[x][y]) leaf page. This way we have a much finer
+ * granularity of setting which PFNs are missing and which ones are identity.
+ * In our example 263424 and 512256 both fail the check so we reserve_brk two
+ * pages. Populate them with INVALID_P2M_ENTRY (so they both have "missing"
+ * values) and assign them to p2m[1][2] and p2m[1][488] respectively.
+ *
+ * At this point we would at minimum reserve_brk one page, but could be up to
+ * three. Each call to set_phys_range_identity has at maximum a three page
+ * cost. If we were to query the P2M at this stage, all those entries from
+ * start PFN through end PFN (so 1029MB -> 2001MB) would return
+ * INVALID_P2M_ENTRY ("missing").
+ *
+ * The next step is to walk from the start pfn to the end pfn setting
+ * the IDENTITY_FRAME_BIT on each PFN. This is done in set_phys_range_identity.
+ * If we find that the middle leaf is pointing to p2m_missing we can swap it
+ * over to p2m_identity - this way covering 4MB (or 2MB) PFN space. At this
+ * point we do not need to worry about boundary aligment (so no need to
+ * reserve_brk a middle page, figure out which PFNs are "missing" and which
+ * ones are identity), as that has been done earlier. If we find that the
+ * middle leaf is not occupied by p2m_identity or p2m_missing, we dereference
+ * that page (which covers 512 PFNs) and set the appropriate PFN with
+ * IDENTITY_FRAME_BIT. In our example 263424 and 512256 end up there, and we
+ * set from p2m[1][2][256->511] and p2m[1][488][0->256] with
+ * IDENTITY_FRAME_BIT set.
+ *
+ * All other regions that are void (or not filled) either point to p2m_missing
+ * (considered missing) or have the default value of INVALID_P2M_ENTRY (also
+ * considered missing). In our case, p2m[1][2][0->255] and p2m[1][488][257->511]
+ * contain the INVALID_P2M_ENTRY value and are considered "missing."
+ *
+ * This is what the p2m ends up looking (for the E820 above) with this
+ * fabulous drawing:
+ *
+ * p2m /--------------\
+ * /-----\ | &mfn_list[0],| /-----------------\
+ * | 0 |------>| &mfn_list[1],| /---------------\ | ~0, ~0, .. |
+ * |-----| | ..., ~0, ~0 | | ~0, ~0, [x]---+----->| IDENTITY [@256] |
+ * | 1 |---\ \--------------/ | [p2m_identity]+\ | IDENTITY [@257] |
+ * |-----| \ | [p2m_identity]+\\ | .... |
+ * | 2 |--\ \-------------------->| ... | \\ \----------------/
+ * |-----| \ \---------------/ \\
+ * | 3 |\ \ \\ p2m_identity
+ * |-----| \ \-------------------->/---------------\ /-----------------\
+ * | .. +->+ | [p2m_identity]+-->| ~0, ~0, ~0, ... |
+ * \-----/ / | [p2m_identity]+-->| ..., ~0 |
+ * / /---------------\ | .... | \-----------------/
+ * / | IDENTITY[@0] | /-+-[x], ~0, ~0.. |
+ * / | IDENTITY[@256]|<----/ \---------------/
+ * / | ~0, ~0, .... |
+ * | \---------------/
+ * |
+ * p2m_missing p2m_missing
+ * /------------------\ /------------\
+ * | [p2m_mid_missing]+---->| ~0, ~0, ~0 |
+ * | [p2m_mid_missing]+---->| ..., ~0 |
+ * \------------------/ \------------/
+ *
+ * where ~0 is INVALID_P2M_ENTRY. IDENTITY is (PFN | IDENTITY_BIT)
+ */
+
+#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 <asm/cache.h>
+#include <asm/setup.h>
+
+#include <asm/xen/page.h>
+#include <asm/xen/hypercall.h>
+#include <asm/xen/hypervisor.h>
+#include <xen/grant_table.h>
+
+#include "multicalls.h"
+#include "xen-ops.h"
+
+static void __init m2p_override_init(void);
+
+unsigned long xen_max_p2m_pfn __read_mostly;
+
+#define P2M_PER_PAGE (PAGE_SIZE / sizeof(unsigned long))
+#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)
+
+/* Placeholders for holes in the address space */
+static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long *, p2m_mid_missing, P2M_MID_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long, p2m_mid_missing_mfn, P2M_MID_PER_PAGE);
+
+static RESERVE_BRK_ARRAY(unsigned long **, p2m_top, P2M_TOP_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, P2M_TOP_PER_PAGE);
+static RESERVE_BRK_ARRAY(unsigned long *, p2m_top_mfn_p, P2M_TOP_PER_PAGE);
+
+static RESERVE_BRK_ARRAY(unsigned long, p2m_identity, P2M_PER_PAGE);
+
+RESERVE_BRK(p2m_mid, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
+RESERVE_BRK(p2m_mid_mfn, PAGE_SIZE * (MAX_DOMAIN_PAGES / (P2M_PER_PAGE * P2M_MID_PER_PAGE)));
+
+/* We might hit two boundary violations at the start and end, at max each
+ * boundary violation will require three middle nodes. */
+RESERVE_BRK(p2m_mid_identity, PAGE_SIZE * 2 * 3);
+
+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_init(unsigned long ***top)
+{
+ unsigned i;
+
+ for (i = 0; i < P2M_TOP_PER_PAGE; i++)
+ top[i] = p2m_mid_missing;
+}
+
+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_init(unsigned long **mid)
+{
+ unsigned i;
+
+ for (i = 0; i < P2M_MID_PER_PAGE; i++)
+ mid[i] = p2m_missing;
+}
+
+static void p2m_mid_mfn_init(unsigned long *mid)
+{
+ unsigned i;
+
+ for (i = 0; i < P2M_MID_PER_PAGE; i++)
+ mid[i] = virt_to_mfn(p2m_missing);
+}
+
+static void p2m_init(unsigned long *p2m)
+{
+ unsigned i;
+
+ for (i = 0; i < P2M_MID_PER_PAGE; i++)
+ p2m[i] = INVALID_P2M_ENTRY;
+}
+
+/*
+ * 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 very early, and must use extend_brk()
+ * to allocate memory.
+ *
+ * - After resume we're called from within stop_machine, but the mfn
+ * tree should alreay be completely allocated.
+ */
+void __ref xen_build_mfn_list_list(void)
+{
+ unsigned long pfn;
+
+ /* Pre-initialize p2m_top_mfn to be completely missing */
+ if (p2m_top_mfn == NULL) {
+ p2m_mid_missing_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_mid_mfn_init(p2m_mid_missing_mfn);
+
+ p2m_top_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_top_mfn_p_init(p2m_top_mfn_p);
+
+ p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_top_mfn_init(p2m_top_mfn);
+ } else {
+ /* Reinitialise, mfn's all change after migration */
+ p2m_mid_mfn_init(p2m_mid_missing_mfn);
+ }
+
+ for (pfn = 0; pfn < xen_max_p2m_pfn; pfn += P2M_PER_PAGE) {
+ unsigned topidx = p2m_top_index(pfn);
+ unsigned mididx = p2m_mid_index(pfn);
+ unsigned long **mid;
+ unsigned long *mid_mfn_p;
+
+ mid = p2m_top[topidx];
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+
+ /* 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 (mid == p2m_mid_missing) {
+ 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) {
+ /*
+ * XXX boot-time only! We should never find
+ * missing parts of the mfn tree after
+ * runtime. extend_brk() will BUG if we call
+ * it too late.
+ */
+ mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_mid_mfn_init(mid_mfn_p);
+
+ p2m_top_mfn_p[topidx] = mid_mfn_p;
+ }
+
+ p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
+ mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]);
+ }
+}
+
+void xen_setup_mfn_list_list(void)
+{
+ BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
+
+ HYPERVISOR_shared_info->arch.pfn_to_mfn_frame_list_list =
+ virt_to_mfn(p2m_top_mfn);
+ HYPERVISOR_shared_info->arch.max_pfn = xen_max_p2m_pfn;
+}
+
+/* Set up p2m_top to point to the domain-builder provided p2m pages */
+void __init xen_build_dynamic_phys_to_machine(void)
+{
+ unsigned long *mfn_list = (unsigned long *)xen_start_info->mfn_list;
+ unsigned long max_pfn = min(MAX_DOMAIN_PAGES, xen_start_info->nr_pages);
+ unsigned long pfn;
+
+ xen_max_p2m_pfn = max_pfn;
+
+ p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_init(p2m_missing);
+
+ p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_mid_init(p2m_mid_missing);
+
+ p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_top_init(p2m_top);
+
+ p2m_identity = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_init(p2m_identity);
+
+ /*
+ * The domain builder gives us a pre-constructed p2m array in
+ * mfn_list for all the pages initially given to us, so we just
+ * need to graft that into our tree structure.
+ */
+ for (pfn = 0; pfn < max_pfn; pfn += P2M_PER_PAGE) {
+ unsigned topidx = p2m_top_index(pfn);
+ unsigned mididx = p2m_mid_index(pfn);
+
+ if (p2m_top[topidx] == p2m_mid_missing) {
+ unsigned long **mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_mid_init(mid);
+
+ p2m_top[topidx] = mid;
+ }
+
+ /*
+ * As long as the mfn_list has enough entries to completely
+ * fill a p2m page, pointing into the array is ok. But if
+ * not the entries beyond the last pfn will be undefined.
+ */
+ if (unlikely(pfn + P2M_PER_PAGE > max_pfn)) {
+ unsigned long p2midx;
+
+ p2midx = max_pfn % P2M_PER_PAGE;
+ for ( ; p2midx < P2M_PER_PAGE; p2midx++)
+ mfn_list[pfn + p2midx] = INVALID_P2M_ENTRY;
+ }
+ p2m_top[topidx][mididx] = &mfn_list[pfn];
+ }
+
+ m2p_override_init();
+}
+
+unsigned long get_phys_to_machine(unsigned long pfn)
+{
+ unsigned topidx, mididx, idx;
+
+ if (unlikely(pfn >= MAX_P2M_PFN))
+ return INVALID_P2M_ENTRY;
+
+ topidx = p2m_top_index(pfn);
+ mididx = p2m_mid_index(pfn);
+ idx = p2m_index(pfn);
+
+ /*
+ * The INVALID_P2M_ENTRY is filled in both p2m_*identity
+ * and in p2m_*missing, so returning the INVALID_P2M_ENTRY
+ * would be wrong.
+ */
+ if (p2m_top[topidx][mididx] == p2m_identity)
+ return IDENTITY_FRAME(pfn);
+
+ return p2m_top[topidx][mididx][idx];
+}
+EXPORT_SYMBOL_GPL(get_phys_to_machine);
+
+static void *alloc_p2m_page(void)
+{
+ return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT);
+}
+
+static void free_p2m_page(void *p)
+{
+ free_page((unsigned long)p);
+}
+
+/*
+ * 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.
+ */
+static bool alloc_p2m(unsigned long pfn)
+{
+ unsigned topidx, mididx;
+ unsigned long ***top_p, **mid;
+ unsigned long *top_mfn_p, *mid_mfn;
+
+ topidx = p2m_top_index(pfn);
+ mididx = p2m_mid_index(pfn);
+
+ top_p = &p2m_top[topidx];
+ mid = *top_p;
+
+ if (mid == p2m_mid_missing) {
+ /* Mid level is missing, allocate a new one */
+ mid = alloc_p2m_page();
+ if (!mid)
+ return false;
+
+ p2m_mid_init(mid);
+
+ if (cmpxchg(top_p, p2m_mid_missing, mid) != p2m_mid_missing)
+ free_p2m_page(mid);
+ }
+
+ top_mfn_p = &p2m_top_mfn[topidx];
+ mid_mfn = 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;
+
+ mid_mfn = alloc_p2m_page();
+ if (!mid_mfn)
+ return false;
+
+ p2m_mid_mfn_init(mid_mfn);
+
+ missing_mfn = virt_to_mfn(p2m_mid_missing_mfn);
+ mid_mfn_mfn = virt_to_mfn(mid_mfn);
+ if (cmpxchg(top_mfn_p, missing_mfn, mid_mfn_mfn) != missing_mfn)
+ free_p2m_page(mid_mfn);
+ else
+ p2m_top_mfn_p[topidx] = mid_mfn;
+ }
+
+ if (p2m_top[topidx][mididx] == p2m_identity ||
+ p2m_top[topidx][mididx] == p2m_missing) {
+ /* p2m leaf page is missing */
+ unsigned long *p2m;
+ unsigned long *p2m_orig = p2m_top[topidx][mididx];
+
+ p2m = alloc_p2m_page();
+ if (!p2m)
+ return false;
+
+ p2m_init(p2m);
+
+ if (cmpxchg(&mid[mididx], p2m_orig, p2m) != p2m_orig)
+ free_p2m_page(p2m);
+ else
+ mid_mfn[mididx] = virt_to_mfn(p2m);
+ }
+
+ return true;
+}
+
+static bool __init __early_alloc_p2m(unsigned long pfn)
+{
+ unsigned topidx, mididx, idx;
+
+ topidx = p2m_top_index(pfn);
+ mididx = p2m_mid_index(pfn);
+ idx = p2m_index(pfn);
+
+ /* Pfff.. No boundary cross-over, lets get out. */
+ if (!idx)
+ return false;
+
+ WARN(p2m_top[topidx][mididx] == p2m_identity,
+ "P2M[%d][%d] == IDENTITY, should be MISSING (or alloced)!\n",
+ topidx, mididx);
+
+ /*
+ * Could be done by xen_build_dynamic_phys_to_machine..
+ */
+ if (p2m_top[topidx][mididx] != p2m_missing)
+ return false;
+
+ /* Boundary cross-over for the edges: */
+ if (idx) {
+ unsigned long *p2m = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ unsigned long *mid_mfn_p;
+
+ p2m_init(p2m);
+
+ p2m_top[topidx][mididx] = p2m;
+
+ /* For save/restore we need to MFN of the P2M saved */
+
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ WARN(mid_mfn_p[mididx] != virt_to_mfn(p2m_missing),
+ "P2M_TOP_P[%d][%d] != MFN of p2m_missing!\n",
+ topidx, mididx);
+ mid_mfn_p[mididx] = virt_to_mfn(p2m);
+
+ }
+ return idx != 0;
+}
+unsigned long __init set_phys_range_identity(unsigned long pfn_s,
+ unsigned long pfn_e)
+{
+ unsigned long pfn;
+
+ if (unlikely(pfn_s >= MAX_P2M_PFN || pfn_e >= MAX_P2M_PFN))
+ return 0;
+
+ if (unlikely(xen_feature(XENFEAT_auto_translated_physmap)))
+ return pfn_e - pfn_s;
+
+ if (pfn_s > pfn_e)
+ return 0;
+
+ for (pfn = (pfn_s & ~(P2M_MID_PER_PAGE * P2M_PER_PAGE - 1));
+ pfn < ALIGN(pfn_e, (P2M_MID_PER_PAGE * P2M_PER_PAGE));
+ pfn += P2M_MID_PER_PAGE * P2M_PER_PAGE)
+ {
+ unsigned topidx = p2m_top_index(pfn);
+ unsigned long *mid_mfn_p;
+ unsigned long **mid;
+
+ mid = p2m_top[topidx];
+ mid_mfn_p = p2m_top_mfn_p[topidx];
+ if (mid == p2m_mid_missing) {
+ mid = extend_brk(PAGE_SIZE, PAGE_SIZE);
+
+ p2m_mid_init(mid);
+
+ p2m_top[topidx] = mid;
+
+ BUG_ON(mid_mfn_p != p2m_mid_missing_mfn);
+ }
+ /* And the save/restore P2M tables.. */
+ if (mid_mfn_p == p2m_mid_missing_mfn) {
+ mid_mfn_p = extend_brk(PAGE_SIZE, PAGE_SIZE);
+ p2m_mid_mfn_init(mid_mfn_p);
+
+ p2m_top_mfn_p[topidx] = mid_mfn_p;
+ p2m_top_mfn[topidx] = virt_to_mfn(mid_mfn_p);
+ /* Note: we don't set mid_mfn_p[midix] here,
+ * look in __early_alloc_p2m */
+ }
+ }
+
+ __early_alloc_p2m(pfn_s);
+ __early_alloc_p2m(pfn_e);
+
+ for (pfn = pfn_s; pfn < pfn_e; pfn++)
+ if (!__set_phys_to_machine(pfn, IDENTITY_FRAME(pfn)))
+ break;
+
+ if (!WARN((pfn - pfn_s) != (pfn_e - pfn_s),
+ "Identity mapping failed. We are %ld short of 1-1 mappings!\n",
+ (pfn_e - pfn_s) - (pfn - pfn_s)))
+ printk(KERN_DEBUG "1-1 mapping on %lx->%lx\n", pfn_s, pfn);
+
+ return pfn - pfn_s;
+}
+
+/* Try to install p2m mapping; fail if intermediate bits missing */
+bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+ unsigned topidx, mididx, idx;
+
+ if (unlikely(xen_feature(XENFEAT_auto_translated_physmap))) {
+ BUG_ON(pfn != mfn && mfn != INVALID_P2M_ENTRY);
+ return true;
+ }
+ if (unlikely(pfn >= MAX_P2M_PFN)) {
+ BUG_ON(mfn != INVALID_P2M_ENTRY);
+ return true;
+ }
+
+ topidx = p2m_top_index(pfn);
+ mididx = p2m_mid_index(pfn);
+ idx = p2m_index(pfn);
+
+ /* For sparse holes were the p2m leaf has real PFN along with
+ * PCI holes, stick in the PFN as the MFN value.
+ */
+ if (mfn != INVALID_P2M_ENTRY && (mfn & IDENTITY_FRAME_BIT)) {
+ if (p2m_top[topidx][mididx] == p2m_identity)
+ return true;
+
+ /* Swap over from MISSING to IDENTITY if needed. */
+ if (p2m_top[topidx][mididx] == p2m_missing) {
+ WARN_ON(cmpxchg(&p2m_top[topidx][mididx], p2m_missing,
+ p2m_identity) != p2m_missing);
+ return true;
+ }
+ }
+
+ if (p2m_top[topidx][mididx] == p2m_missing)
+ return mfn == INVALID_P2M_ENTRY;
+
+ p2m_top[topidx][mididx][idx] = mfn;
+
+ return true;
+}
+
+bool set_phys_to_machine(unsigned long pfn, unsigned long mfn)
+{
+ if (unlikely(!__set_phys_to_machine(pfn, mfn))) {
+ if (!alloc_p2m(pfn))
+ return false;
+
+ if (!__set_phys_to_machine(pfn, mfn))
+ return false;
+ }
+
+ return true;
+}
+
+#define M2P_OVERRIDE_HASH_SHIFT 10
+#define M2P_OVERRIDE_HASH (1 << M2P_OVERRIDE_HASH_SHIFT)
+
+static RESERVE_BRK_ARRAY(struct list_head, m2p_overrides, M2P_OVERRIDE_HASH);
+static DEFINE_SPINLOCK(m2p_override_lock);
+
+static void __init m2p_override_init(void)
+{
+ unsigned i;
+
+ m2p_overrides = extend_brk(sizeof(*m2p_overrides) * M2P_OVERRIDE_HASH,
+ sizeof(unsigned long));
+
+ for (i = 0; i < M2P_OVERRIDE_HASH; i++)
+ INIT_LIST_HEAD(&m2p_overrides[i]);
+}
+
+static unsigned long mfn_hash(unsigned long mfn)
+{
+ return hash_long(mfn, M2P_OVERRIDE_HASH_SHIFT);
+}
+
+/* Add an MFN override for a particular page */
+int m2p_add_override(unsigned long mfn, struct page *page,
+ struct gnttab_map_grant_ref *kmap_op)
+{
+ unsigned long flags;
+ unsigned long pfn;
+ unsigned long uninitialized_var(address);
+ unsigned level;
+ pte_t *ptep = NULL;
+
+ pfn = page_to_pfn(page);
+ if (!PageHighMem(page)) {
+ address = (unsigned long)__va(pfn << PAGE_SHIFT);
+ ptep = lookup_address(address, &level);
+ if (WARN(ptep == NULL || level != PG_LEVEL_4K,
+ "m2p_add_override: pfn %lx not mapped", pfn))
+ return -EINVAL;
+ }
+ WARN_ON(PagePrivate(page));
+ SetPagePrivate(page);
+ set_page_private(page, mfn);
+ page->index = pfn_to_mfn(pfn);
+
+ if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
+ return -ENOMEM;
+
+ if (kmap_op != NULL) {
+ if (!PageHighMem(page)) {
+ struct multicall_space mcs =
+ xen_mc_entry(sizeof(*kmap_op));
+
+ MULTI_grant_table_op(mcs.mc,
+ GNTTABOP_map_grant_ref, kmap_op, 1);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+ }
+ /* let's use dev_bus_addr to record the old mfn instead */
+ kmap_op->dev_bus_addr = page->index;
+ page->index = (unsigned long) kmap_op;
+ }
+ spin_lock_irqsave(&m2p_override_lock, flags);
+ list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
+ spin_unlock_irqrestore(&m2p_override_lock, flags);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(m2p_add_override);
+int m2p_remove_override(struct page *page, bool clear_pte)
+{
+ unsigned long flags;
+ unsigned long mfn;
+ unsigned long pfn;
+ unsigned long uninitialized_var(address);
+ unsigned level;
+ pte_t *ptep = NULL;
+
+ pfn = page_to_pfn(page);
+ mfn = get_phys_to_machine(pfn);
+ if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
+ return -EINVAL;
+
+ if (!PageHighMem(page)) {
+ address = (unsigned long)__va(pfn << PAGE_SHIFT);
+ ptep = lookup_address(address, &level);
+
+ if (WARN(ptep == NULL || level != PG_LEVEL_4K,
+ "m2p_remove_override: pfn %lx not mapped", pfn))
+ return -EINVAL;
+ }
+
+ spin_lock_irqsave(&m2p_override_lock, flags);
+ list_del(&page->lru);
+ spin_unlock_irqrestore(&m2p_override_lock, flags);
+ WARN_ON(!PagePrivate(page));
+ ClearPagePrivate(page);
+
+ if (clear_pte) {
+ struct gnttab_map_grant_ref *map_op =
+ (struct gnttab_map_grant_ref *) page->index;
+ set_phys_to_machine(pfn, map_op->dev_bus_addr);
+ if (!PageHighMem(page)) {
+ struct multicall_space mcs;
+ struct gnttab_unmap_grant_ref *unmap_op;
+
+ /*
+ * It might be that we queued all the m2p grant table
+ * hypercalls in a multicall, then m2p_remove_override
+ * get called before the multicall has actually been
+ * issued. In this case handle is going to -1 because
+ * it hasn't been modified yet.
+ */
+ if (map_op->handle == -1)
+ xen_mc_flush();
+ /*
+ * Now if map_op->handle is negative it means that the
+ * hypercall actually returned an error.
+ */
+ if (map_op->handle == GNTST_general_error) {
+ printk(KERN_WARNING "m2p_remove_override: "
+ "pfn %lx mfn %lx, failed to modify kernel mappings",
+ pfn, mfn);
+ return -1;
+ }
+
+ mcs = xen_mc_entry(
+ sizeof(struct gnttab_unmap_grant_ref));
+ unmap_op = mcs.args;
+ unmap_op->host_addr = map_op->host_addr;
+ unmap_op->handle = map_op->handle;
+ unmap_op->dev_bus_addr = 0;
+
+ MULTI_grant_table_op(mcs.mc,
+ GNTTABOP_unmap_grant_ref, unmap_op, 1);
+
+ xen_mc_issue(PARAVIRT_LAZY_MMU);
+
+ set_pte_at(&init_mm, address, ptep,
+ pfn_pte(pfn, PAGE_KERNEL));
+ __flush_tlb_single(address);
+ map_op->host_addr = 0;
+ }
+ } else
+ set_phys_to_machine(pfn, page->index);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(m2p_remove_override);
+
+struct page *m2p_find_override(unsigned long mfn)
+{
+ unsigned long flags;
+ struct list_head *bucket = &m2p_overrides[mfn_hash(mfn)];
+ struct page *p, *ret;
+
+ ret = NULL;
+
+ spin_lock_irqsave(&m2p_override_lock, flags);
+
+ list_for_each_entry(p, bucket, lru) {
+ if (page_private(p) == mfn) {
+ ret = p;
+ break;
+ }
+ }
+
+ spin_unlock_irqrestore(&m2p_override_lock, flags);
+
+ return ret;
+}
+
+unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn)
+{
+ struct page *p = m2p_find_override(mfn);
+ unsigned long ret = pfn;
+
+ if (p)
+ ret = page_to_pfn(p);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(m2p_find_override_pfn);
+
+#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 level_name[] = { "top", "middle",
+ "entry", "abnormal", "error"};
+#define TYPE_IDENTITY 0
+#define TYPE_MISSING 1
+#define TYPE_PFN 2
+#define TYPE_UNKNOWN 3
+ static const char * const type_name[] = {
+ [TYPE_IDENTITY] = "identity",
+ [TYPE_MISSING] = "missing",
+ [TYPE_PFN] = "pfn",
+ [TYPE_UNKNOWN] = "abnormal"};
+ unsigned long pfn, prev_pfn_type = 0, prev_pfn_level = 0;
+ unsigned int uninitialized_var(prev_level);
+ unsigned int uninitialized_var(prev_type);
+
+ if (!p2m_top)
+ return 0;
+
+ for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn++) {
+ unsigned topidx = p2m_top_index(pfn);
+ unsigned mididx = p2m_mid_index(pfn);
+ unsigned idx = p2m_index(pfn);
+ unsigned lvl, type;
+
+ lvl = 4;
+ type = TYPE_UNKNOWN;
+ if (p2m_top[topidx] == p2m_mid_missing) {
+ lvl = 0; type = TYPE_MISSING;
+ } else if (p2m_top[topidx] == NULL) {
+ lvl = 0; type = TYPE_UNKNOWN;
+ } else if (p2m_top[topidx][mididx] == NULL) {
+ lvl = 1; type = TYPE_UNKNOWN;
+ } else if (p2m_top[topidx][mididx] == p2m_identity) {
+ lvl = 1; type = TYPE_IDENTITY;
+ } else if (p2m_top[topidx][mididx] == p2m_missing) {
+ lvl = 1; type = TYPE_MISSING;
+ } else if (p2m_top[topidx][mididx][idx] == 0) {
+ lvl = 2; type = TYPE_UNKNOWN;
+ } else if (p2m_top[topidx][mididx][idx] == IDENTITY_FRAME(pfn)) {
+ lvl = 2; type = TYPE_IDENTITY;
+ } else if (p2m_top[topidx][mididx][idx] == INVALID_P2M_ENTRY) {
+ lvl = 2; type = TYPE_MISSING;
+ } else if (p2m_top[topidx][mididx][idx] == pfn) {
+ lvl = 2; type = TYPE_PFN;
+ } else if (p2m_top[topidx][mididx][idx] != pfn) {
+ lvl = 2; type = TYPE_PFN;
+ }
+ if (pfn == 0) {
+ prev_level = lvl;
+ prev_type = type;
+ }
+ if (pfn == MAX_DOMAIN_PAGES-1) {
+ lvl = 3;
+ type = TYPE_UNKNOWN;
+ }
+ if (prev_type != type) {
+ seq_printf(m, " [0x%lx->0x%lx] %s\n",
+ prev_pfn_type, pfn, type_name[prev_type]);
+ prev_pfn_type = pfn;
+ prev_type = type;
+ }
+ if (prev_level != lvl) {
+ seq_printf(m, " [0x%lx->0x%lx] level %s\n",
+ prev_pfn_level, pfn, level_name[prev_level]);
+ prev_pfn_level = pfn;
+ prev_level = lvl;
+ }
+ }
+ return 0;
+#undef TYPE_IDENTITY
+#undef TYPE_MISSING
+#undef TYPE_PFN
+#undef TYPE_UNKNOWN
+}
+
+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 */