Again, (out-of-memory) errors must not cause hypervisor crashes, and hence ought to be propagated. This also adjusts the cache attribute changing loop in get_page_from_l1e() to not go through an unnecessary iteration. While this could be considered mere cleanup, it is actually a requirement for the subsequent now necessary error recovery path. Also make a few functions static, easing the check for potential callers needing adjustment. Signed-off-by: Jan Beulich --- 2011-03-09.orig/xen/arch/x86/mm.c +++ 2011-03-09/xen/arch/x86/mm.c @@ -767,8 +767,9 @@ int is_iomem_page(unsigned long mfn) return (page_get_owner(page) == dom_io); } -static void update_xen_mappings(unsigned long mfn, unsigned long cacheattr) +static int update_xen_mappings(unsigned long mfn, unsigned long cacheattr) { + int err = 0; #ifdef __x86_64__ bool_t alias = mfn >= PFN_DOWN(xen_phys_start) && mfn < PFN_UP(xen_phys_start + (unsigned long)_end - XEN_VIRT_START); @@ -776,12 +777,14 @@ static void update_xen_mappings(unsigned XEN_VIRT_START + ((mfn - PFN_DOWN(xen_phys_start)) << PAGE_SHIFT); if ( unlikely(alias) && cacheattr ) - map_pages_to_xen(xen_va, mfn, 1, 0); - map_pages_to_xen((unsigned long)mfn_to_virt(mfn), mfn, 1, + err = map_pages_to_xen(xen_va, mfn, 1, 0); + if ( !err ) + err = map_pages_to_xen((unsigned long)mfn_to_virt(mfn), mfn, 1, PAGE_HYPERVISOR | cacheattr_to_pte_flags(cacheattr)); - if ( unlikely(alias) && !cacheattr ) - map_pages_to_xen(xen_va, mfn, 1, PAGE_HYPERVISOR); + if ( unlikely(alias) && !cacheattr && !err ) + err = map_pages_to_xen(xen_va, mfn, 1, PAGE_HYPERVISOR); #endif + return err; } int @@ -793,6 +796,7 @@ get_page_from_l1e( uint32_t l1f = l1e_get_flags(l1e); struct vcpu *curr = current; struct domain *real_pg_owner; + bool_t write; if ( !(l1f & _PAGE_PRESENT) ) return 1; @@ -849,9 +853,9 @@ get_page_from_l1e( * contribute to writeable mapping refcounts. (This allows the * qemu-dm helper process in dom0 to map the domain's memory without * messing up the count of "real" writable mappings.) */ - if ( (l1f & _PAGE_RW) && - ((l1e_owner == pg_owner) || !paging_mode_external(pg_owner)) && - !get_page_type(page, PGT_writable_page) ) + write = (l1f & _PAGE_RW) && + ((l1e_owner == pg_owner) || !paging_mode_external(pg_owner)); + if ( write && !get_page_type(page, PGT_writable_page) ) goto could_not_pin; if ( pte_flags_to_cacheattr(l1f) != @@ -862,22 +866,36 @@ get_page_from_l1e( if ( is_xen_heap_page(page) ) { - if ( (l1f & _PAGE_RW) && - ((l1e_owner == pg_owner) || !paging_mode_external(pg_owner)) ) + if ( write ) put_page_type(page); put_page(page); MEM_LOG("Attempt to change cache attributes of Xen heap page"); return 0; } - while ( ((y & PGC_cacheattr_mask) >> PGC_cacheattr_base) != cacheattr ) - { + do { x = y; nx = (x & ~PGC_cacheattr_mask) | (cacheattr << PGC_cacheattr_base); - y = cmpxchg(&page->count_info, x, nx); - } + } while ( (y = cmpxchg(&page->count_info, x, nx)) != x ); + + if ( unlikely(update_xen_mappings(mfn, cacheattr) != 0) ) + { + cacheattr = y & PGC_cacheattr_mask; + do { + x = y; + nx = (x & ~PGC_cacheattr_mask) | cacheattr; + } while ( (y = cmpxchg(&page->count_info, x, nx)) != x ); + + if ( write ) + put_page_type(page); + put_page(page); - update_xen_mappings(mfn, cacheattr); + MEM_LOG("Error updating mappings for mfn %lx (pfn %lx," + " from L1 entry %" PRIpte ") for %d", + mfn, get_gpfn_from_mfn(mfn), + l1e_get_intpte(l1e), l1e_owner->domain_id); + return 0; + } } return 1; @@ -2005,6 +2023,21 @@ static int mod_l4_entry(l4_pgentry_t *pl #endif +static int cleanup_page_cacheattr(struct page_info *page) +{ + uint32_t cacheattr = + (page->count_info & PGC_cacheattr_mask) >> PGC_cacheattr_base; + + if ( likely(cacheattr == 0) ) + return 0; + + page->count_info &= ~PGC_cacheattr_mask; + + BUG_ON(is_xen_heap_page(page)); + + return update_xen_mappings(page_to_mfn(page), 0); +} + void put_page(struct page_info *page) { unsigned long nx, x, y = page->count_info; @@ -2018,8 +2051,10 @@ void put_page(struct page_info *page) if ( unlikely((nx & PGC_count_mask) == 0) ) { - cleanup_page_cacheattr(page); - free_domheap_page(page); + if ( cleanup_page_cacheattr(page) == 0 ) + free_domheap_page(page); + else + MEM_LOG("Leaking pfn %lx", page_to_mfn(page)); } } @@ -2678,21 +2713,6 @@ static void put_superpage(unsigned long #endif -void cleanup_page_cacheattr(struct page_info *page) -{ - uint32_t cacheattr = - (page->count_info & PGC_cacheattr_mask) >> PGC_cacheattr_base; - - if ( likely(cacheattr == 0) ) - return; - - page->count_info &= ~PGC_cacheattr_mask; - - BUG_ON(is_xen_heap_page(page)); - - update_xen_mappings(page_to_mfn(page), 0); -} - int new_guest_cr3(unsigned long mfn) { --- 2011-03-09.orig/xen/arch/x86/x86_64/mm.c +++ 2011-03-09/xen/arch/x86/x86_64/mm.c @@ -439,6 +439,7 @@ static int setup_compat_m2p_table(struct l3_pgentry_t *l3_ro_mpt = NULL; l2_pgentry_t *l2_ro_mpt = NULL; struct page_info *l1_pg; + int err = 0; smap = info->spfn & (~((1UL << (L2_PAGETABLE_SHIFT - 2)) -1)); @@ -489,24 +490,25 @@ static int setup_compat_m2p_table(struct memflags = MEMF_node(phys_to_nid(i << PAGE_SHIFT)); l1_pg = mfn_to_page(alloc_hotadd_mfn(info)); - map_pages_to_xen(rwva, - page_to_mfn(l1_pg), - 1UL << PAGETABLE_ORDER, - PAGE_HYPERVISOR); + err = map_pages_to_xen(rwva, page_to_mfn(l1_pg), + 1UL << PAGETABLE_ORDER, + PAGE_HYPERVISOR); + if ( err ) + break; memset((void *)rwva, 0x55, 1UL << L2_PAGETABLE_SHIFT); /* NB. Cannot be GLOBAL as the ptes get copied into per-VM space. */ l2e_write(&l2_ro_mpt[l2_table_offset(va)], l2e_from_page(l1_pg, _PAGE_PSE|_PAGE_PRESENT)); } #undef CNT #undef MFN - return 0; + return err; } /* * Allocate and map the machine-to-phys table. * The L3 for RO/RWRW MPT and the L2 for compatible MPT should be setup already */ -int setup_m2p_table(struct mem_hotadd_info *info) +static int setup_m2p_table(struct mem_hotadd_info *info) { unsigned long i, va, smap, emap; unsigned int n, memflags; @@ -560,11 +562,13 @@ int setup_m2p_table(struct mem_hotadd_in else { l1_pg = mfn_to_page(alloc_hotadd_mfn(info)); - map_pages_to_xen( + ret = map_pages_to_xen( RDWR_MPT_VIRT_START + i * sizeof(unsigned long), page_to_mfn(l1_pg), 1UL << PAGETABLE_ORDER, PAGE_HYPERVISOR); + if ( ret ) + goto error; memset((void *)(RDWR_MPT_VIRT_START + i * sizeof(unsigned long)), 0x55, 1UL << L2_PAGETABLE_SHIFT); @@ -908,13 +912,13 @@ void cleanup_frame_table(struct mem_hota flush_tlb_all(); } -/* Should we be paraniod failure in map_pages_to_xen? */ static int setup_frametable_chunk(void *start, void *end, struct mem_hotadd_info *info) { unsigned long s = (unsigned long)start; unsigned long e = (unsigned long)end; unsigned long mfn; + int err; ASSERT(!(s & ((1 << L2_PAGETABLE_SHIFT) - 1))); ASSERT(!(e & ((1 << L2_PAGETABLE_SHIFT) - 1))); @@ -922,14 +926,17 @@ static int setup_frametable_chunk(void * for ( ; s < e; s += (1UL << L2_PAGETABLE_SHIFT)) { mfn = alloc_hotadd_mfn(info); - map_pages_to_xen(s, mfn, 1UL << PAGETABLE_ORDER, PAGE_HYPERVISOR); + err = map_pages_to_xen(s, mfn, 1UL << PAGETABLE_ORDER, + PAGE_HYPERVISOR); + if ( err ) + return err; } memset(start, -1, s - (unsigned long)start); return 0; } -int extend_frame_table(struct mem_hotadd_info *info) +static int extend_frame_table(struct mem_hotadd_info *info) { unsigned long cidx, nidx, eidx, spfn, epfn; @@ -950,12 +957,16 @@ int extend_frame_table(struct mem_hotadd while ( cidx < eidx ) { + int err; + nidx = find_next_bit(pdx_group_valid, eidx, cidx); if ( nidx >= eidx ) nidx = eidx; - setup_frametable_chunk(pdx_to_page(cidx * PDX_GROUP_COUNT ), + err = setup_frametable_chunk(pdx_to_page(cidx * PDX_GROUP_COUNT ), pdx_to_page(nidx * PDX_GROUP_COUNT), info); + if ( err ) + return err; cidx = find_next_zero_bit(pdx_group_valid, eidx, nidx); } --- 2011-03-09.orig/xen/include/asm-x86/mm.h +++ 2011-03-09/xen/include/asm-x86/mm.h @@ -325,8 +325,6 @@ int free_page_type(struct page_info *pag int preemptible); int _shadow_mode_refcounts(struct domain *d); -void cleanup_page_cacheattr(struct page_info *page); - int is_iomem_page(unsigned long mfn); void clear_superpage_mark(struct page_info *page);