| /* |
| * 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); |
| |
| /* When we populate back during bootup, the amount of pages can vary. The |
| * max we have is seen is 395979, but that does not mean it can't be more. |
| * Some machines can have 3GB I/O holes even. With early_can_reuse_p2m_middle |
| * it can re-use Xen provided mfn_list array, so we only need to allocate at |
| * most three P2M top nodes. */ |
| RESERVE_BRK(p2m_populated, PAGE_SIZE * 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_middle(unsigned long pfn, bool check_boundary) |
| { |
| unsigned topidx, mididx, idx; |
| unsigned long *p2m; |
| unsigned long *mid_mfn_p; |
| |
| topidx = p2m_top_index(pfn); |
| mididx = p2m_mid_index(pfn); |
| idx = p2m_index(pfn); |
| |
| /* Pfff.. No boundary cross-over, lets get out. */ |
| if (!idx && check_boundary) |
| 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: */ |
| p2m = extend_brk(PAGE_SIZE, PAGE_SIZE); |
| |
| 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 true; |
| } |
| |
| static bool __init early_alloc_p2m(unsigned long pfn) |
| { |
| 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_middle */ |
| } |
| return true; |
| } |
| |
| /* |
| * Skim over the P2M tree looking at pages that are either filled with |
| * INVALID_P2M_ENTRY or with 1:1 PFNs. If found, re-use that page and |
| * replace the P2M leaf with a p2m_missing or p2m_identity. |
| * Stick the old page in the new P2M tree location. |
| */ |
| bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_mfn) |
| { |
| unsigned topidx; |
| unsigned mididx; |
| unsigned ident_pfns; |
| unsigned inv_pfns; |
| unsigned long *p2m; |
| unsigned long *mid_mfn_p; |
| unsigned idx; |
| unsigned long pfn; |
| |
| /* We only look when this entails a P2M middle layer */ |
| if (p2m_index(set_pfn)) |
| return false; |
| |
| for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) { |
| topidx = p2m_top_index(pfn); |
| |
| if (!p2m_top[topidx]) |
| continue; |
| |
| if (p2m_top[topidx] == p2m_mid_missing) |
| continue; |
| |
| mididx = p2m_mid_index(pfn); |
| p2m = p2m_top[topidx][mididx]; |
| if (!p2m) |
| continue; |
| |
| if ((p2m == p2m_missing) || (p2m == p2m_identity)) |
| continue; |
| |
| if ((unsigned long)p2m == INVALID_P2M_ENTRY) |
| continue; |
| |
| ident_pfns = 0; |
| inv_pfns = 0; |
| for (idx = 0; idx < P2M_PER_PAGE; idx++) { |
| /* IDENTITY_PFNs are 1:1 */ |
| if (p2m[idx] == IDENTITY_FRAME(pfn + idx)) |
| ident_pfns++; |
| else if (p2m[idx] == INVALID_P2M_ENTRY) |
| inv_pfns++; |
| else |
| break; |
| } |
| if ((ident_pfns == P2M_PER_PAGE) || (inv_pfns == P2M_PER_PAGE)) |
| goto found; |
| } |
| return false; |
| found: |
| /* Found one, replace old with p2m_identity or p2m_missing */ |
| p2m_top[topidx][mididx] = (ident_pfns ? p2m_identity : p2m_missing); |
| /* And the other for save/restore.. */ |
| mid_mfn_p = p2m_top_mfn_p[topidx]; |
| /* NOTE: Even if it is a p2m_identity it should still be point to |
| * a page filled with INVALID_P2M_ENTRY entries. */ |
| mid_mfn_p[mididx] = virt_to_mfn(p2m_missing); |
| |
| /* Reset where we want to stick the old page in. */ |
| topidx = p2m_top_index(set_pfn); |
| mididx = p2m_mid_index(set_pfn); |
| |
| /* This shouldn't happen */ |
| if (WARN_ON(p2m_top[topidx] == p2m_mid_missing)) |
| early_alloc_p2m(set_pfn); |
| |
| if (WARN_ON(p2m_top[topidx][mididx] != p2m_missing)) |
| return false; |
| |
| p2m_init(p2m); |
| p2m_top[topidx][mididx] = p2m; |
| mid_mfn_p = p2m_top_mfn_p[topidx]; |
| mid_mfn_p[mididx] = virt_to_mfn(p2m); |
| |
| return true; |
| } |
| bool __init early_set_phys_to_machine(unsigned long pfn, unsigned long mfn) |
| { |
| if (unlikely(!__set_phys_to_machine(pfn, mfn))) { |
| if (!early_alloc_p2m(pfn)) |
| return false; |
| |
| if (early_can_reuse_p2m_middle(pfn, mfn)) |
| return __set_phys_to_machine(pfn, mfn); |
| |
| if (!early_alloc_p2m_middle(pfn, false /* boundary crossover OK!*/)) |
| return false; |
| |
| if (!__set_phys_to_machine(pfn, mfn)) |
| return false; |
| } |
| |
| return true; |
| } |
| 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) |
| { |
| WARN_ON(!early_alloc_p2m(pfn)); |
| } |
| |
| early_alloc_p2m_middle(pfn_s, true); |
| early_alloc_p2m_middle(pfn_e, true); |
| |
| 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; |
| int ret = 0; |
| |
| 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); |
| } |
| } |
| spin_lock_irqsave(&m2p_override_lock, flags); |
| list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); |
| spin_unlock_irqrestore(&m2p_override_lock, flags); |
| |
| /* p2m(m2p(mfn)) == mfn: the mfn is already present somewhere in |
| * this domain. Set the FOREIGN_FRAME_BIT in the p2m for the other |
| * pfn so that the following mfn_to_pfn(mfn) calls will return the |
| * pfn from the m2p_override (the backend pfn) instead. |
| * We need to do this because the pages shared by the frontend |
| * (xen-blkfront) can be already locked (lock_page, called by |
| * do_read_cache_page); when the userspace backend tries to use them |
| * with direct_IO, mfn_to_pfn returns the pfn of the frontend, so |
| * do_blockdev_direct_IO is going to try to lock the same pages |
| * again resulting in a deadlock. |
| * As a side effect get_user_pages_fast might not be safe on the |
| * frontend pages while they are being shared with the backend, |
| * because mfn_to_pfn (that ends up being called by GUPF) will |
| * return the backend pfn rather than the frontend pfn. */ |
| ret = __get_user(pfn, &machine_to_phys_mapping[mfn]); |
| if (ret == 0 && get_phys_to_machine(pfn) == mfn) |
| set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)); |
| |
| return 0; |
| } |
| EXPORT_SYMBOL_GPL(m2p_add_override); |
| int m2p_remove_override(struct page *page, |
| struct gnttab_map_grant_ref *kmap_op) |
| { |
| unsigned long flags; |
| unsigned long mfn; |
| unsigned long pfn; |
| unsigned long uninitialized_var(address); |
| unsigned level; |
| pte_t *ptep = NULL; |
| int ret = 0; |
| |
| 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); |
| |
| set_phys_to_machine(pfn, page->index); |
| if (kmap_op != NULL) { |
| 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 (kmap_op->handle == -1) |
| xen_mc_flush(); |
| /* |
| * Now if kmap_op->handle is negative it means that the |
| * hypercall actually returned an error. |
| */ |
| if (kmap_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 = kmap_op->host_addr; |
| unmap_op->handle = kmap_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); |
| kmap_op->host_addr = 0; |
| } |
| } |
| |
| /* p2m(m2p(mfn)) == FOREIGN_FRAME(mfn): the mfn is already present |
| * somewhere in this domain, even before being added to the |
| * m2p_override (see comment above in m2p_add_override). |
| * If there are no other entries in the m2p_override corresponding |
| * to this mfn, then remove the FOREIGN_FRAME_BIT from the p2m for |
| * the original pfn (the one shared by the frontend): the backend |
| * cannot do any IO on this page anymore because it has been |
| * unshared. Removing the FOREIGN_FRAME_BIT from the p2m entry of |
| * the original pfn causes mfn_to_pfn(mfn) to return the frontend |
| * pfn again. */ |
| mfn &= ~FOREIGN_FRAME_BIT; |
| ret = __get_user(pfn, &machine_to_phys_mapping[mfn]); |
| if (ret == 0 && get_phys_to_machine(pfn) == FOREIGN_FRAME(mfn) && |
| m2p_find_override(mfn) == NULL) |
| set_phys_to_machine(pfn, mfn); |
| |
| 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 */ |