[PATCH v12 0/6] populate/unpopulate memory when domain on static allocation

[Penny Zheng <Penny.Zheng@xxxxxxx>]

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.

---
v12 changes:
- it should be acquire_domstatic_pages() calling unprepare_staticmem_pages()
on failing
- add in-code comment
---
v11 changes:
- printing message ahead of the assertion, which should also be
XENLOG_G_* kind of log level
- commit message tweak
- move "xen: rename free_staticmem_pages to unprepare_staticmem_pages" ahead
of "xen: retrieve reserved pages on populate_physmap"
- with assignment having failed and the page not exposed to the guest at any
point, there is no need for scrubbing
---
v10 changes:
- let Arm keep #define PGC_static 0 private, with the generic fallback
remaining in page_alloc.c
- change ASSERT(d) to ASSERT_UNREACHABLE() to be more robust looking
forward, and also add a printk() to log the problem
- mention the the removal of #ifdef CONFIG_STATIC_MEMORY in commit
message
- commit message typo fix
- Do not skip the list addition in that one special case
- add lock on the fail path
- new commit "xen: rename free_staticmem_pages to unprepare_staticmem_pages"
---
v9 changes:
- move free_domheap_page into else-condition
- considering scrubbing static pages, domain dying case and opt_scrub_domheap
both do not apply to static pages.
- as unowned static pages don't make themselves to free_domstatic_page
at the moment, remove else-condition and add ASSERT(d) at the top of the
function
- remove macro helper put_static_page, and just expand its code inside
free_domstatic_page
- Use ASSERT_ALLOC_CONTEXT() in acquire_reserved_page
- Add free_staticmem_pages to undo prepare_staticmem_pages when
assign_domstatic_pages fails
- Remove redundant static in error message
---
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 (6):
  xen: do not free reserved memory into heap
  xen/arm: introduce CDF_staticmem
  xen: unpopulate memory when domain is static
  xen: introduce prepare_staticmem_pages
  xen: rename free_staticmem_pages to unprepare_staticmem_pages
  xen: retrieve reserved pages on populate_physmap

 xen/arch/arm/domain_build.c   |   5 +-
 xen/arch/arm/include/asm/mm.h |   6 +-
 xen/arch/arm/mm.c             |   5 +-
 xen/arch/arm/setup.c          |   3 +-
 xen/common/domain.c           |   4 +
 xen/common/memory.c           |  23 +++++
 xen/common/page_alloc.c       | 173 ++++++++++++++++++++++++++--------
 xen/include/xen/domain.h      |   8 ++
 xen/include/xen/mm.h          |   8 +-
 xen/include/xen/sched.h       |   3 +
 10 files changed, 192 insertions(+), 46 deletions(-)

-- 
2.25.1