[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3 9/9] mm: Make sure pages are scrubbed
Add a debug Kconfig option that will make page allocator verify that pages that were supposed to be scrubbed are, in fact, clean. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> --- xen/Kconfig.debug | 7 ++++++ xen/common/page_alloc.c | 49 ++++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 55 insertions(+), 1 deletions(-) diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug index 689f297..f3bf9a9 100644 --- a/xen/Kconfig.debug +++ b/xen/Kconfig.debug @@ -114,6 +114,13 @@ config DEVICE_TREE_DEBUG logged in the Xen ring buffer. If unsure, say N here. +config SCRUB_DEBUG + bool "Page scrubbing test" + default DEBUG + ---help--- + Verify that pages that need to be scrubbed before being allocated to + a guest are indeed scrubbed. + endif # DEBUG || EXPERT endmenu diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c index dd6f248..18c80d7 100644 --- a/xen/common/page_alloc.c +++ b/xen/common/page_alloc.c @@ -694,6 +694,31 @@ static void page_list_add_scrub(struct page_info *pg, unsigned int node, page_list_add(pg, &heap(node, zone, order)); } +#define SCRUB_BYTE_PATTERN 0xc2c2c2c2c2c2c2c2 +#ifdef CONFIG_SCRUB_DEBUG +static void poison_one_page(struct page_info *pg) +{ + mfn_t mfn = _mfn(page_to_mfn(pg)); + uint64_t *ptr; + + ptr = map_domain_page(mfn); + *ptr = ~SCRUB_BYTE_PATTERN; + unmap_domain_page(ptr); +} + +static void check_one_page(struct page_info *pg) +{ + mfn_t mfn = _mfn(page_to_mfn(pg)); + uint64_t *ptr; + unsigned i; + + ptr = map_domain_page(mfn); + for ( i = 0; i < PAGE_SIZE / sizeof (*ptr); i++ ) + ASSERT(ptr[i] == SCRUB_BYTE_PATTERN); + unmap_domain_page(ptr); +} +#endif /* CONFIG_SCRUB_DEBUG */ + static void check_and_stop_scrub(struct page_info *head) { if ( head->u.free.scrub_state & PAGE_SCRUBBING ) @@ -912,6 +937,11 @@ static struct page_info *alloc_heap_pages( * guest can control its own visibility of/through the cache. */ flush_page_to_ram(page_to_mfn(&pg[i])); + +#ifdef CONFIG_SCRUB_DEBUG + if ( d && !is_idle_domain(d) ) + check_one_page(&pg[i]); +#endif } spin_unlock(&heap_lock); @@ -1341,6 +1371,11 @@ static void free_heap_pages( pg[i].count_info |= PGC_need_scrub; node_need_scrub[node] += (1UL << order); + +#ifdef CONFIG_SCRUB_DEBUG + for ( i = 0; i < (1 << order); i++ ) + poison_one_page(&pg[i]); +#endif } pg = merge_and_free_buddy(pg, node, zone, order, need_scrub, false); @@ -1637,6 +1672,14 @@ static void init_heap_pages( nr_pages -= n; } +#ifdef CONFIG_SCRUB_DEBUG + /* + * These pages get into heap and are allocated to dom0 before + * boot scrub happens. + * Not scrubbing them here will cause failure in check_one_page(). + */ + scrub_one_page(pg + i); +#endif free_heap_pages(pg + i, 0, false); } } @@ -2170,6 +2213,9 @@ void free_domheap_pages(struct page_info *pg, unsigned int order) { BUG_ON((pg[i].u.inuse.type_info & PGT_count_mask) != 0); arch_free_heap_page(d, &pg[i]); +#ifdef CONFIG_SCRUB_DEBUG + scrub_one_page(&pg[i]); +#endif } drop_dom_ref = !domain_adjust_tot_pages(d, -(1 << order)); @@ -2273,7 +2319,8 @@ void scrub_one_page(struct page_info *pg) #ifndef NDEBUG /* Avoid callers relying on allocations returning zeroed pages. */ - unmap_domain_page(memset(__map_domain_page(pg), 0xc2, PAGE_SIZE)); + unmap_domain_page(memset(__map_domain_page(pg), + SCRUB_BYTE_PATTERN & 0xff, PAGE_SIZE)); #else /* For a production build, clear_page() is the fastest way to scrub. */ clear_domain_page(_mfn(page_to_mfn(pg))); -- 1.7.1 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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