Today when a domain unpopulates the memory on runtime, they will always hand the memory over to the heap allocator. And it will be a problem if it is a static domain. Pages used as guest RAM for static domain shall always be reserved to this domain only, and not be used for any other purposes, so they shall never go back to heap allocator.
This patch serie intends to fix this issue, by adding pages on the new list resv_page_list after having taken them off the "normal" list, when unpopulating memory, and retrieving pages from resv page list(resv_page_list) when populating memory. --- v8 changes: - introduce new helper free_domstatic_page - let put_page call free_domstatic_page for static page, when last ref drops - #define PGC_static zero when !CONFIG_STATIC_MEMORY, as it is used outside page_alloc.c - #ifdef-ary around is_domain_using_staticmem() is not needed anymore - order as a parameter is not needed here, as all staticmem operations are limited to order-0 regions - move d->page_alloc_lock after operation on d->resv_page_list - As concurrent free/allocate could modify the resv_page_list, we still need the lock --- v7 changes: - protect free_staticmem_pages with heap_lock to match its reverse function acquire_staticmem_pages - IS_ENABLED(CONFIG_STATIC_MEMORY) would not be needed anymore - add page on the rsv_page_list *after* it has been freed - remove the lock, since we add the page to rsv_page_list after it has been totally freed. --- v6 changes: - rename PGC_staticmem to PGC_static - remove #ifdef aroud function declaration - use domain instead of sub-systems - move non-zero is_domain_using_staticmem() from ARM header to common header - move PGC_static !CONFIG_STATIC_MEMORY definition to common header - drop the lock before returning --- v5 changes: - introduce three new commits - In order to avoid stub functions, we #define PGC_staticmem to non-zero only when CONFIG_STATIC_MEMORY - use "unlikely()" around pg->count_info & PGC_staticmem - remove pointless "if", since mark_page_free() is going to set count_info to PGC_state_free and by consequence clear PGC_staticmem - move #define PGC_staticmem 0 to mm.h - guard "is_domain_using_staticmem" under CONFIG_STATIC_MEMORY - #define is_domain_using_staticmem zero if undefined - extract common codes for assigning pages into a helper assign_domstatic_pages - refine commit message - remove stub function acquire_reserved_page - Alloc/free of memory can happen concurrently. So access to rsv_page_list needs to be protected with a spinlock --- v4 changes: - commit message refinement - miss dropping __init in acquire_domstatic_pages - add the page back to the reserved list in case of error - remove redundant printk - refine log message and make it warn level - guard "is_domain_using_staticmem" under CONFIG_STATIC_MEMORY - #define is_domain_using_staticmem zero if undefined --- v3 changes: - fix possible racy issue in free_staticmem_pages() - introduce a stub free_staticmem_pages() for the !CONFIG_STATIC_MEMORY case - move the change to free_heap_pages() to cover other potential call sites - change fixed width type uint32_t to unsigned int - change "flags" to a more descriptive name "cdf" - change name from "is_domain_static()" to "is_domain_using_staticmem" - have page_list_del() just once out of the if() - remove resv_pages counter - make arch_free_heap_page be an expression, not a compound statement. - move #ifndef is_domain_using_staticmem to the common header file - remove #ifdef CONFIG_STATIC_MEMORY-ary - remove meaningless page_to_mfn(page) in error log --- v2 changes: - let "flags" live in the struct domain. So other arch can take advantage of it in the future - change name from "is_domain_on_static_allocation" to "is_domain_static()" - put reserved pages on resv_page_list after having taken them off the "normal" list - introduce acquire_reserved_page to retrieve reserved pages from resv_page_list - forbid non-zero-order requests in populate_physmap - let is_domain_static return ((void)(d), false) on x86 - fix coding style Penny Zheng (9): xen/arm: rename PGC_reserved to PGC_static xen: do not free reserved memory into heap xen: update SUPPORT.md for static allocation xen: do not merge reserved pages in free_heap_pages() xen: add field "flags" to cover all internal CDF_XXX xen/arm: introduce CDF_staticmem xen/arm: unpopulate memory when domain is static xen: introduce prepare_staticmem_pages xen: retrieve reserved pages on populate_physmap SUPPORT.md | 7 ++ xen/arch/arm/domain.c | 2 - xen/arch/arm/domain_build.c | 5 +- xen/arch/arm/include/asm/domain.h | 3 +- xen/arch/arm/include/asm/mm.h | 8 +- xen/arch/arm/mm.c | 2 + xen/common/domain.c | 7 ++ xen/common/memory.c | 23 ++++ xen/common/page_alloc.c | 190 ++++++++++++++++++++++-------- xen/include/xen/domain.h | 8 ++ xen/include/xen/mm.h | 12 +- xen/include/xen/sched.h | 6 + 12 files changed, 215 insertions(+), 58 deletions(-) -- 2.25.1
