diff options
-rw-r--r-- | arch/x86/xen/Kconfig | 11 | ||||
-rw-r--r-- | arch/x86/xen/mmu.c | 318 |
2 files changed, 246 insertions, 83 deletions
diff --git a/arch/x86/xen/Kconfig b/arch/x86/xen/Kconfig index 68128a1b401a..90a7f5ad6916 100644 --- a/arch/x86/xen/Kconfig +++ b/arch/x86/xen/Kconfig @@ -19,15 +19,12 @@ config XEN_PVHVM depends on X86_LOCAL_APIC config XEN_MAX_DOMAIN_MEMORY - int "Maximum allowed size of a domain in gigabytes" - default 8 if X86_32 - default 32 if X86_64 + int + default 128 depends on XEN help - The pseudo-physical to machine address array is sized - according to the maximum possible memory size of a Xen - domain. This array uses 1 page per gigabyte, so there's no - need to be too stingy here. + This only affects the sizing of some bss arrays, the unused + portions of which are freed. config XEN_SAVE_RESTORE bool diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c index 00969099b057..d4c7265cf0a0 100644 --- a/arch/x86/xen/mmu.c +++ b/arch/x86/xen/mmu.c @@ -170,51 +170,162 @@ DEFINE_PER_CPU(unsigned long, xen_current_cr3); /* actual vcpu cr3 */ */ #define USER_LIMIT ((STACK_TOP_MAX + PGDIR_SIZE - 1) & PGDIR_MASK) -static unsigned long max_p2m_pfn __read_mostly = MAX_DOMAIN_PAGES; +/* + * 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_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. + */ -#define P2M_ENTRIES_PER_PAGE (PAGE_SIZE / sizeof(unsigned long)) -#define TOP_ENTRIES(pages) ((pages) / P2M_ENTRIES_PER_PAGE) -#define MAX_TOP_ENTRIES TOP_ENTRIES(MAX_DOMAIN_PAGES) +static unsigned long max_p2m_pfn __read_mostly; -/* Placeholder for holes in the address space */ -static RESERVE_BRK_ARRAY(unsigned long, p2m_missing, P2M_ENTRIES_PER_PAGE); +#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 **)) - /* Array of pointers to pages containing p2m entries */ -static RESERVE_BRK_ARRAY(unsigned long *, p2m_top, MAX_TOP_ENTRIES); +#define MAX_P2M_PFN (P2M_TOP_PER_PAGE * P2M_MID_PER_PAGE * P2M_PER_PAGE) -/* Arrays of p2m arrays expressed in mfns used for save/restore */ -static RESERVE_BRK_ARRAY(unsigned long, p2m_top_mfn, MAX_TOP_ENTRIES); +/* 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_mfn_list, - (MAX_TOP_ENTRIES / P2M_ENTRIES_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); + +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))); static inline unsigned p2m_top_index(unsigned long pfn) { - BUG_ON(pfn >= max_p2m_pfn); - return pfn / P2M_ENTRIES_PER_PAGE; + 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_ENTRIES_PER_PAGE; + return pfn % P2M_PER_PAGE; } -/* Build the parallel p2m_top_mfn structures */ +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_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 xen_build_mfn_list_list(void) { - unsigned pfn, idx; + unsigned pfn, i; - for (pfn = 0; pfn < max_p2m_pfn; pfn += P2M_ENTRIES_PER_PAGE) { - unsigned topidx = p2m_top_index(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[topidx] = virt_to_mfn(p2m_top[topidx]); + p2m_top_mfn = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_top_mfn_init(p2m_top_mfn); } - for (idx = 0; - idx < TOP_ENTRIES(max_p2m_pfn)/P2M_ENTRIES_PER_PAGE; - idx++) { - unsigned topidx = idx * P2M_ENTRIES_PER_PAGE; - p2m_top_mfn_list[idx] = virt_to_mfn(&p2m_top_mfn[topidx]); + for (pfn = 0; pfn < 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; + unsigned long *mid_mfn_p; + + mid = p2m_top[topidx]; + + /* Don't bother allocating any mfn mid levels if + they're just missing */ + if (mid[mididx] == p2m_missing) + continue; + + mid_mfn = p2m_top_mfn[topidx]; + mid_mfn_p = mfn_to_virt(mid_mfn); + + 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); + + mid_mfn = virt_to_mfn(mid_mfn_p); + + p2m_top_mfn[topidx] = mid_mfn; + } + + mid_mfn_p[mididx] = virt_to_mfn(mid[mididx]); } } @@ -223,7 +334,7 @@ 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_list); + virt_to_mfn(p2m_top_mfn); HYPERVISOR_shared_info->arch.max_pfn = max_p2m_pfn; } @@ -233,99 +344,154 @@ 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 pfn; - unsigned i; max_p2m_pfn = max_pfn; - p2m_missing = extend_brk(sizeof(*p2m_missing) * P2M_ENTRIES_PER_PAGE, - PAGE_SIZE); - for (i = 0; i < P2M_ENTRIES_PER_PAGE; i++) - p2m_missing[i] = ~0UL; + p2m_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_init(p2m_missing); - p2m_top = extend_brk(sizeof(*p2m_top) * TOP_ENTRIES(max_pfn), - PAGE_SIZE); - for (i = 0; i < TOP_ENTRIES(max_pfn); i++) - p2m_top[i] = p2m_missing; + p2m_mid_missing = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_mid_init(p2m_mid_missing); - p2m_top_mfn = extend_brk(sizeof(*p2m_top_mfn) * TOP_ENTRIES(max_pfn), - PAGE_SIZE); - p2m_top_mfn_list = extend_brk(sizeof(*p2m_top_mfn_list) * - (TOP_ENTRIES(max_pfn) / P2M_ENTRIES_PER_PAGE), - PAGE_SIZE); + p2m_top = extend_brk(PAGE_SIZE, PAGE_SIZE); + p2m_top_init(p2m_top); - for (pfn = 0; pfn < max_pfn; pfn += P2M_ENTRIES_PER_PAGE) { + /* + * 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] = &mfn_list[pfn]; + p2m_top[topidx] = mid; + } + + p2m_top[topidx][mididx] = &mfn_list[pfn]; } + /* Allocate and initialize top and mid mfn levels */ xen_build_mfn_list_list(); } unsigned long get_phys_to_machine(unsigned long pfn) { - unsigned topidx, idx; + unsigned topidx, mididx, idx; - if (unlikely(pfn >= max_p2m_pfn)) + if (unlikely(pfn >= MAX_P2M_PFN)) return INVALID_P2M_ENTRY; topidx = p2m_top_index(pfn); + mididx = p2m_mid_index(pfn); idx = p2m_index(pfn); - return p2m_top[topidx][idx]; + + return p2m_top[topidx][mididx][idx]; } EXPORT_SYMBOL_GPL(get_phys_to_machine); -/* install a new p2m_top page */ -static bool install_p2mtop_page(unsigned long pfn, unsigned long *p) +static void *alloc_p2m_page(void) { - unsigned topidx = p2m_top_index(pfn); - unsigned long **pfnp, *mfnp; - unsigned i; + return (void *)__get_free_page(GFP_KERNEL | __GFP_REPEAT); +} - pfnp = &p2m_top[topidx]; - mfnp = &p2m_top_mfn[topidx]; +static void free_p2m_page(void *p) +{ + free_page((unsigned long)p); +} - for (i = 0; i < P2M_ENTRIES_PER_PAGE; i++) - p[i] = INVALID_P2M_ENTRY; +/* + * 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; - if (cmpxchg(pfnp, p2m_missing, p) == p2m_missing) { - *mfnp = virt_to_mfn(p); - return true; + 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); } - return false; -} + top_mfn_p = &p2m_top_mfn[topidx]; + mid_mfn = mfn_to_virt(*top_mfn_p); -static void alloc_p2m(unsigned long pfn) -{ - unsigned long *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); + } - p = (void *)__get_free_page(GFP_KERNEL | __GFP_NOFAIL); - BUG_ON(p == NULL); + if (p2m_top[topidx][mididx] == p2m_missing) { + /* p2m leaf page is missing */ + unsigned long *p2m; - if (!install_p2mtop_page(pfn, p)) - free_page((unsigned long)p); + p2m = alloc_p2m_page(); + if (!p2m) + return false; + + p2m_init(p2m); + + if (cmpxchg(&mid[mididx], p2m_missing, p2m) != p2m_missing) + free_p2m_page(p2m); + else + mid_mfn[mididx] = virt_to_mfn(p2m); + } + + return true; } /* Try to install p2m mapping; fail if intermediate bits missing */ bool __set_phys_to_machine(unsigned long pfn, unsigned long mfn) { - unsigned topidx, idx; + unsigned topidx, mididx, idx; - if (unlikely(pfn >= max_p2m_pfn)) { + if (unlikely(pfn >= MAX_P2M_PFN)) { BUG_ON(mfn != INVALID_P2M_ENTRY); return true; } topidx = p2m_top_index(pfn); - if (p2m_top[topidx] == p2m_missing) { - if (mfn == INVALID_P2M_ENTRY) - return true; - return false; - } - + mididx = p2m_mid_index(pfn); idx = p2m_index(pfn); - p2m_top[topidx][idx] = mfn; + + if (p2m_top[topidx][mididx] == p2m_missing) + return mfn == INVALID_P2M_ENTRY; + + p2m_top[topidx][mididx][idx] = mfn; return true; } @@ -338,7 +504,7 @@ void set_phys_to_machine(unsigned long pfn, unsigned long mfn) } if (unlikely(!__set_phys_to_machine(pfn, mfn))) { - alloc_p2m(pfn); + WARN(!alloc_p2m(pfn), "Can't allocate p2m for %lx, %lx", pfn, mfn); if (!__set_phys_to_machine(pfn, mfn)) BUG(); |