diff options
Diffstat (limited to 'arch/x86/xen/p2m.c')
| -rw-r--r-- | arch/x86/xen/p2m.c | 140 |
1 files changed, 98 insertions, 42 deletions
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 1b267e75158d..64effdc6da94 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -499,16 +499,18 @@ static bool alloc_p2m(unsigned long pfn) return true; } -static bool __init __early_alloc_p2m(unsigned long pfn) +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) + if (!idx && check_boundary) return false; WARN(p2m_top[topidx][mididx] == p2m_identity, @@ -522,24 +524,66 @@ static bool __init __early_alloc_p2m(unsigned long pfn) 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 = extend_brk(PAGE_SIZE, PAGE_SIZE); - p2m_init(p2m); + p2m_init(p2m); - p2m_top[topidx][mididx] = 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); + /* 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 idx != 0; + 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_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) @@ -559,35 +603,11 @@ unsigned long __init set_phys_range_identity(unsigned long pfn_s, 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 */ - } + WARN_ON(!early_alloc_p2m(pfn)); } - __early_alloc_p2m(pfn_s); - __early_alloc_p2m(pfn_e); + 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))) @@ -686,6 +706,7 @@ int m2p_add_override(unsigned long mfn, struct page *page, unsigned long uninitialized_var(address); unsigned level; pte_t *ptep = NULL; + int ret = 0; pfn = page_to_pfn(page); if (!PageHighMem(page)) { @@ -721,6 +742,24 @@ int m2p_add_override(unsigned long mfn, struct page *page, 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); @@ -732,6 +771,7 @@ int m2p_remove_override(struct page *page, bool clear_pte) 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); @@ -801,6 +841,22 @@ int m2p_remove_override(struct page *page, bool clear_pte) } else set_phys_to_machine(pfn, page->index); + /* 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); |