[PATCH v8 0/9] populate/unpopulate memory when domain on static allocation

[PATCH v8 0/9] populate/unpopulate memory when domain on static allocation

[Penny Zheng]

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

[PATCH v8 1/9] xen/arm: rename PGC_reserved to PGC_static

[Penny Zheng]

PGC_reserved could be ambiguous, and we have to tell what the pages are
reserved for, so this commit intends to rename PGC_reserved to
PGC_static, which clearly indicates the page is reserved for static
memory.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
v8 changes
- no change
---
v7 changes:
- no change
---
v6 changes:
- rename PGC_staticmem to PGC_static
---
v5 changes:
- new commit
---
 xen/arch/arm/include/asm/mm.h |  6 +++---
 xen/common/page_alloc.c       | 22 +++++++++++-----------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index c4bc3cd1e5..8b2481c1f3 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -108,9 +108,9 @@ struct page_info
   /* Page is Xen heap? */
 #define _PGC_xen_heap     PG_shift(2)
 #define PGC_xen_heap      PG_mask(1, 2)
-  /* Page is reserved */
-#define _PGC_reserved     PG_shift(3)
-#define PGC_reserved      PG_mask(1, 3)
+  /* Page is static memory */
+#define _PGC_static    PG_shift(3)
+#define PGC_static     PG_mask(1, 3)
 /* ... */
 /* Page is broken? */
 #define _PGC_broken       PG_shift(7)
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index fe0e15429a..ed56379b96 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -151,8 +151,8 @@
 #define p2m_pod_offline_or_broken_replace(pg) BUG_ON(pg != NULL)
 #endif
 
-#ifndef PGC_reserved
-#define PGC_reserved 0
+#ifndef PGC_static
+#define PGC_static 0
 #endif
 
 /*
@@ -2286,7 +2286,7 @@ int assign_pages(
 
         for ( i = 0; i < nr; i++ )
         {
-            ASSERT(!(pg[i].count_info & ~(PGC_extra | PGC_reserved)));
+            ASSERT(!(pg[i].count_info & ~(PGC_extra | PGC_static)));
             if ( pg[i].count_info & PGC_extra )
                 extra_pages++;
         }
@@ -2346,7 +2346,7 @@ int assign_pages(
         page_set_owner(&pg[i], d);
         smp_wmb(); /* Domain pointer must be visible before updating refcnt. */
         pg[i].count_info =
-            (pg[i].count_info & (PGC_extra | PGC_reserved)) | PGC_allocated | 1;
+            (pg[i].count_info & (PGC_extra | PGC_static)) | PGC_allocated | 1;
 
         page_list_add_tail(&pg[i], page_to_list(d, &pg[i]));
     }
@@ -2652,8 +2652,8 @@ void __init free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
             scrub_one_page(pg);
         }
 
-        /* In case initializing page of static memory, mark it PGC_reserved. */
-        pg[i].count_info |= PGC_reserved;
+        /* In case initializing page of static memory, mark it PGC_static. */
+        pg[i].count_info |= PGC_static;
     }
 }
 
@@ -2682,8 +2682,8 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
 
     for ( i = 0; i < nr_mfns; i++ )
     {
-        /* The page should be reserved and not yet allocated. */
-        if ( pg[i].count_info != (PGC_state_free | PGC_reserved) )
+        /* The page should be static and not yet allocated. */
+        if ( pg[i].count_info != (PGC_state_free | PGC_static) )
         {
             printk(XENLOG_ERR
                    "pg[%lu] Static MFN %"PRI_mfn" c=%#lx t=%#x\n",
@@ -2697,10 +2697,10 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
                                 &tlbflush_timestamp);
 
         /*
-         * Preserve flag PGC_reserved and change page state
+         * Preserve flag PGC_static and change page state
          * to PGC_state_inuse.
          */
-        pg[i].count_info = PGC_reserved | PGC_state_inuse;
+        pg[i].count_info = PGC_static | PGC_state_inuse;
         /* Initialise fields which have other uses for free pages. */
         pg[i].u.inuse.type_info = 0;
         page_set_owner(&pg[i], NULL);
@@ -2722,7 +2722,7 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
 
  out_err:
     while ( i-- )
-        pg[i].count_info = PGC_reserved | PGC_state_free;
+        pg[i].count_info = PGC_static | PGC_state_free;
 
     spin_unlock(&heap_lock);
 
-- 
2.25.1

[PATCH v8 2/9] xen: do not free reserved memory into heap

[Penny Zheng]

Pages used as guest RAM for static domain, shall be reserved to this
domain only.
So in case reserved pages being used for other purpose, users
shall not free them back to heap, even when last ref gets dropped.

This commit introduces a new helper free_domstatic_page to free
static page in runtime, and free_staticmem_pages will be called by it
in runtime, so let's drop the __init flag.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
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 in xen/mm.h, as it
is used outside page_alloc.c
---
v7 changes:
- protect free_staticmem_pages with heap_lock to match its reverse function
acquire_staticmem_pages
---
v6 changes:
- adapt to PGC_static
- remove #ifdef aroud function declaration
---
v5 changes:
- 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
---
v4 changes:
- no changes
---
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
- fix the indentation
---
v2 changes:
- new commit
---
---
 xen/arch/arm/include/asm/mm.h |  4 ++-
 xen/arch/arm/mm.c             |  2 ++
 xen/common/page_alloc.c       | 51 ++++++++++++++++++++++++++++++-----
 xen/include/xen/mm.h          |  7 +++--
 4 files changed, 54 insertions(+), 10 deletions(-)

diff --git a/xen/arch/arm/include/asm/mm.h b/xen/arch/arm/include/asm/mm.h
index 8b2481c1f3..f1640bbda4 100644
--- a/xen/arch/arm/include/asm/mm.h
+++ b/xen/arch/arm/include/asm/mm.h
@@ -108,9 +108,11 @@ struct page_info
   /* Page is Xen heap? */
 #define _PGC_xen_heap     PG_shift(2)
 #define PGC_xen_heap      PG_mask(1, 2)
-  /* Page is static memory */
+#ifdef CONFIG_STATIC_MEMORY
+/* Page is static memory */
 #define _PGC_static    PG_shift(3)
 #define PGC_static     PG_mask(1, 3)
+#endif
 /* ... */
 /* Page is broken? */
 #define _PGC_broken       PG_shift(7)
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 009b8cd9ef..a3bc6d7a24 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -1622,6 +1622,8 @@ void put_page(struct page_info *page)
 
     if ( unlikely((nx & PGC_count_mask) == 0) )
     {
+        if ( unlikely(nx & PGC_static) )
+            free_domstatic_page(page);
         free_domheap_page(page);
     }
 }
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index ed56379b96..9a80ca10fa 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -151,10 +151,6 @@
 #define p2m_pod_offline_or_broken_replace(pg) BUG_ON(pg != NULL)
 #endif
 
-#ifndef PGC_static
-#define PGC_static 0
-#endif
-
 /*
  * Comma-separated list of hexadecimal page numbers containing bad bytes.
  * e.g. 'badpage=0x3f45,0x8a321'.
@@ -2636,12 +2632,14 @@ struct domain *get_pg_owner(domid_t domid)
 
 #ifdef CONFIG_STATIC_MEMORY
 /* Equivalent of free_heap_pages to free nr_mfns pages of static memory. */
-void __init free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
-                                 bool need_scrub)
+void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
+                          bool need_scrub)
 {
     mfn_t mfn = page_to_mfn(pg);
     unsigned long i;
 
+    spin_lock(&heap_lock);
+
     for ( i = 0; i < nr_mfns; i++ )
     {
         mark_page_free(&pg[i], mfn_add(mfn, i));
@@ -2652,9 +2650,48 @@ void __init free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
             scrub_one_page(pg);
         }
 
-        /* In case initializing page of static memory, mark it PGC_static. */
         pg[i].count_info |= PGC_static;
     }
+
+    spin_unlock(&heap_lock);
+}
+
+void free_domstatic_page(struct page_info *page)
+{
+    struct domain *d = page_get_owner(page);
+    bool drop_dom_ref, need_scrub;
+
+    ASSERT_ALLOC_CONTEXT();
+
+    if ( likely(d) )
+    {
+        /* NB. May recursively lock from relinquish_memory(). */
+        spin_lock_recursive(&d->page_alloc_lock);
+
+        arch_free_heap_page(d, page);
+
+        /*
+         * Normally we expect a domain to clear pages before freeing them,
+         * if it cares about the secrecy of their contents. However, after
+         * a domain has died we assume responsibility for erasure. We do
+         * scrub regardless if option scrub_domheap is set.
+         */
+        need_scrub = d->is_dying || scrub_debug || opt_scrub_domheap;
+
+        drop_dom_ref = !domain_adjust_tot_pages(d, -1);
+
+        spin_unlock_recursive(&d->page_alloc_lock);
+    }
+    else
+    {
+        drop_dom_ref = false;
+        need_scrub = true;
+    }
+
+    free_staticmem_pages(page, 1, need_scrub);
+
+    if ( drop_dom_ref )
+        put_domain(d);
 }
 
 /*
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 3be754da92..f1a7d5c991 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -85,13 +85,12 @@ bool scrub_free_pages(void);
 } while ( false )
 #define FREE_XENHEAP_PAGE(p) FREE_XENHEAP_PAGES(p, 0)
 
-#ifdef CONFIG_STATIC_MEMORY
 /* These functions are for static memory */
 void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
                           bool need_scrub);
+void free_domstatic_page(struct page_info *page);
 int acquire_domstatic_pages(struct domain *d, mfn_t smfn, unsigned int nr_mfns,
                             unsigned int memflags);
-#endif
 
 /* Map machine page range in Xen virtual address space. */
 int map_pages_to_xen(
@@ -212,6 +211,10 @@ extern struct domain *dom_cow;
 
 #include <asm/mm.h>
 
+#ifndef PGC_static
+#define PGC_static 0
+#endif
+
 static inline bool is_special_page(const struct page_info *page)
 {
     return is_xen_heap_page(page) || (page->count_info & PGC_extra);
-- 
2.25.1

[PATCH v8 3/9] xen: update SUPPORT.md for static allocation

[Penny Zheng]

SUPPORT.md doesn't seem to explicitly say whether static memory is
supported, so this commit updates SUPPORT.md to add feature static
allocation tech preview for now.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
---
v8 changes:
- no change
---
v7 changes:
- no change
---
v6 changes:
- use domain instead of sub-systems
---
v5 changes:
- new commit
---
 SUPPORT.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/SUPPORT.md b/SUPPORT.md
index 70e98964cb..8e040d1c1e 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -286,6 +286,13 @@ to boot with memory < maxmem.
 
     Status, x86 HVM: Supported
 
+### Static Allocation
+
+Static allocation refers to domains for which memory areas are
+pre-defined by configuration using physical address ranges.
+
+    Status, ARM: Tech Preview
+
 ### Memory Sharing
 
 Allow sharing of identical pages between guests
-- 
2.25.1

[PATCH v8 4/9] xen: do not merge reserved pages in free_heap_pages()

[Penny Zheng]

The code in free_heap_pages() will try to merge pages with the
successor/predecessor if pages are suitably aligned. So if the pages
reserved are right next to the pages given to the heap allocator,
free_heap_pages() will merge them, and give the reserved pages to heap
allocator accidently as a result.

So in order to avoid the above scenario, this commit updates free_heap_pages()
to check whether the predecessor and/or successor has PGC_reserved set,
when trying to merge the about-to-be-freed chunk with the predecessor
and/or successor.

Suggested-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <jgrall@amazon.com>
---
v8 changes:
- no change
---
v7 changes:
- no change
---
v6 changes:
- adapt to PGC_static
---
v5 changes:
- change PGC_reserved to adapt to PGC_staticmem
---
v4 changes:
- no changes
---
v3 changes:
- no changes
---
v2 changes:
- new commit
---
 xen/common/page_alloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 9a80ca10fa..3260490688 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -1475,6 +1475,7 @@ static void free_heap_pages(
             /* Merge with predecessor block? */
             if ( !mfn_valid(page_to_mfn(predecessor)) ||
                  !page_state_is(predecessor, free) ||
+                 (predecessor->count_info & PGC_static) ||
                  (PFN_ORDER(predecessor) != order) ||
                  (phys_to_nid(page_to_maddr(predecessor)) != node) )
                 break;
@@ -1498,6 +1499,7 @@ static void free_heap_pages(
             /* Merge with successor block? */
             if ( !mfn_valid(page_to_mfn(successor)) ||
                  !page_state_is(successor, free) ||
+                 (successor->count_info & PGC_static) ||
                  (PFN_ORDER(successor) != order) ||
                  (phys_to_nid(page_to_maddr(successor)) != node) )
                 break;
-- 
2.25.1

[PATCH v8 5/9] xen: add field "flags" to cover all internal CDF_XXX

[Penny Zheng]

With more and more CDF_xxx internal flags in and to save the space, this
commit introduces a new field "flags" in struct domain to store CDF_*
internal flags directly.

Another new CDF_xxx will be introduced in the next patch.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Acked-by: Julien Grall <jgrall@amazon.com>
---
v8 changes:
- no change
---
v7 changes:
- no change
---
v6 changes:
- no change
---
v5 changes:
- no change
---
v4 changes:
- no change
---
v3 changes:
- change fixed width type uint32_t to unsigned int
- change "flags" to a more descriptive name "cdf"
---
v2 changes:
- let "flags" live in the struct domain. So other arch can take
advantage of it in the future
- fix coding style
---
 xen/arch/arm/domain.c             | 2 --
 xen/arch/arm/include/asm/domain.h | 3 +--
 xen/common/domain.c               | 3 +++
 xen/include/xen/sched.h           | 3 +++
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 2f8eaab7b5..4722988ee7 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -709,8 +709,6 @@ int arch_domain_create(struct domain *d,
     ioreq_domain_init(d);
 #endif
 
-    d->arch.directmap = flags & CDF_directmap;
-
     /* p2m_init relies on some value initialized by the IOMMU subsystem */
     if ( (rc = iommu_domain_init(d, config->iommu_opts)) != 0 )
         goto fail;
diff --git a/xen/arch/arm/include/asm/domain.h b/xen/arch/arm/include/asm/domain.h
index ed63c2b6f9..fe7a029ebf 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -29,7 +29,7 @@ enum domain_type {
 #define is_64bit_domain(d) (0)
 #endif
 
-#define is_domain_direct_mapped(d) (d)->arch.directmap
+#define is_domain_direct_mapped(d) ((d)->cdf & CDF_directmap)
 
 /*
  * Is the domain using the host memory layout?
@@ -103,7 +103,6 @@ struct arch_domain
     void *tee;
 #endif
 
-    bool directmap;
 }  __cacheline_aligned;
 
 struct arch_vcpu
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 3b1169d79b..875730df50 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -567,6 +567,9 @@ struct domain *domain_create(domid_t domid,
     /* Sort out our idea of is_system_domain(). */
     d->domain_id = domid;
 
+    /* Holding CDF_* internal flags. */
+    d->cdf = flags;
+
     /* Debug sanity. */
     ASSERT(is_system_domain(d) ? config == NULL : config != NULL);
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index b9515eb497..98e8001c89 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -596,6 +596,9 @@ struct domain
         struct ioreq_server     *server[MAX_NR_IOREQ_SERVERS];
     } ioreq_server;
 #endif
+
+    /* Holding CDF_* constant. Internal flags for domain creation. */
+    unsigned int cdf;
 };
 
 static inline struct page_list_head *page_to_list(
-- 
2.25.1

[PATCH v8 6/9] xen/arm: introduce CDF_staticmem

[Penny Zheng]

In order to have an easy and quick way to find out whether this domain memory
is statically configured, this commit introduces a new flag CDF_staticmem and a
new helper is_domain_using_staticmem() to tell.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v8 changes:
- #ifdef-ary around is_domain_using_staticmem() is not needed anymore
---
v7 changes:
- IS_ENABLED(CONFIG_STATIC_MEMORY) would not be needed anymore
---
v6 changes:
- move non-zero is_domain_using_staticmem() from ARM header to common
header
---
v5 changes:
- guard "is_domain_using_staticmem" under CONFIG_STATIC_MEMORY
- #define is_domain_using_staticmem zero if undefined
---
v4 changes:
- no changes
---
v3 changes:
- change name from "is_domain_static()" to "is_domain_using_staticmem"
---
v2 changes:
- change name from "is_domain_on_static_allocation" to "is_domain_static()"
---
 xen/arch/arm/domain_build.c | 5 ++++-
 xen/include/xen/domain.h    | 8 ++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 3fd1186b53..b76a84e8f5 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -3287,9 +3287,12 @@ void __init create_domUs(void)
         if ( !dt_device_is_compatible(node, "xen,domain") )
             continue;
 
+        if ( dt_find_property(node, "xen,static-mem", NULL) )
+            flags |= CDF_staticmem;
+
         if ( dt_property_read_bool(node, "direct-map") )
         {
-            if ( !IS_ENABLED(CONFIG_STATIC_MEMORY) || !dt_find_property(node, "xen,static-mem", NULL) )
+            if ( !(flags & CDF_staticmem) )
                 panic("direct-map is not valid for domain %s without static allocation.\n",
                       dt_node_name(node));
 
diff --git a/xen/include/xen/domain.h b/xen/include/xen/domain.h
index 628b14b086..2c8116afba 100644
--- a/xen/include/xen/domain.h
+++ b/xen/include/xen/domain.h
@@ -35,6 +35,14 @@ void arch_get_domain_info(const struct domain *d,
 /* Should domain memory be directly mapped? */
 #define CDF_directmap            (1U << 1)
 #endif
+/* Is domain memory on static allocation? */
+#ifdef CONFIG_STATIC_MEMORY
+#define CDF_staticmem            (1U << 2)
+#else
+#define CDF_staticmem            0
+#endif
+
+#define is_domain_using_staticmem(d) ((d)->cdf & CDF_staticmem)
 
 /*
  * Arch-specifics.
-- 
2.25.1

[PATCH v8 7/9] xen/arm: unpopulate memory when domain is static

[Penny Zheng]

Today when a domain unpopulates the memory on runtime, they will always
hand the memory back to the heap allocator. And it will be a problem if domain
is static.

Pages as guest RAM for static domain shall be reserved to only this domain
and not be used for any other purposes, so they shall never go back to heap
allocator.

This commit puts reserved pages on the new list resv_page_list only after
having taken them off the "normal" list, when the last ref dropped.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v8 changes:
- adapt this patch for newly introduced free_domstatic_page
- 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
---
v7 changes:
- Add page on the rsv_page_list *after* it has been freed
---
v6 changes:
- refine in-code comment
- move PGC_static !CONFIG_STATIC_MEMORY definition to common header
---
v5 changes:
- adapt this patch for PGC_staticmem
---
v4 changes:
- no changes
---
v3 changes:
- 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.
---
v2 changes:
- put reserved pages on resv_page_list after having taken them off
the "normal" list
---
 xen/common/domain.c     |  4 ++++
 xen/common/page_alloc.c | 10 ++++++++--
 xen/include/xen/mm.h    |  6 ++++++
 xen/include/xen/sched.h |  3 +++
 4 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/xen/common/domain.c b/xen/common/domain.c
index 875730df50..4043498ffa 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -604,6 +604,10 @@ struct domain *domain_create(domid_t domid,
     INIT_PAGE_LIST_HEAD(&d->page_list);
     INIT_PAGE_LIST_HEAD(&d->extra_page_list);
     INIT_PAGE_LIST_HEAD(&d->xenpage_list);
+#ifdef CONFIG_STATIC_MEMORY
+    INIT_PAGE_LIST_HEAD(&d->resv_page_list);
+#endif
+
 
     spin_lock_init(&d->node_affinity_lock);
     d->node_affinity = NODE_MASK_ALL;
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 3260490688..b01272a59a 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2681,8 +2681,6 @@ void free_domstatic_page(struct page_info *page)
         need_scrub = d->is_dying || scrub_debug || opt_scrub_domheap;
 
         drop_dom_ref = !domain_adjust_tot_pages(d, -1);
-
-        spin_unlock_recursive(&d->page_alloc_lock);
     }
     else
     {
@@ -2692,6 +2690,14 @@ void free_domstatic_page(struct page_info *page)
 
     free_staticmem_pages(page, 1, need_scrub);
 
+    if ( likely(d) )
+    {
+        /* Add page on the resv_page_list *after* it has been freed. */
+        if ( !drop_dom_ref )
+            put_static_page(d, page);
+        spin_unlock_recursive(&d->page_alloc_lock);
+    }
+
     if ( drop_dom_ref )
         put_domain(d);
 }
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index f1a7d5c991..07b8a45f1a 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -91,6 +91,12 @@ void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
 void free_domstatic_page(struct page_info *page);
 int acquire_domstatic_pages(struct domain *d, mfn_t smfn, unsigned int nr_mfns,
                             unsigned int memflags);
+#ifdef CONFIG_STATIC_MEMORY
+#define put_static_page(d, page) \
+    page_list_add_tail((page), &(d)->resv_page_list)
+#else
+#define put_static_page(d, page) ((void)(d), (void)(page))
+#endif
 
 /* Map machine page range in Xen virtual address space. */
 int map_pages_to_xen(
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 98e8001c89..d4fbd3dea7 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -381,6 +381,9 @@ struct domain
     struct page_list_head page_list;  /* linked list */
     struct page_list_head extra_page_list; /* linked list (size extra_pages) */
     struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */
+#ifdef CONFIG_STATIC_MEMORY
+    struct page_list_head resv_page_list; /* linked list */
+#endif
 
     /*
      * This field should only be directly accessed by domain_adjust_tot_pages()
-- 
2.25.1

[PATCH v8 8/9] xen: introduce prepare_staticmem_pages

[Penny Zheng]

Later, we want to use acquire_domstatic_pages() for populating memory
for static domain on runtime, however, there are a lot of pointless work
(checking mfn_valid(), scrubbing the free part, cleaning the cache...)
considering we know the page is valid and belong to the guest.

This commit splits acquire_staticmem_pages() in two parts, and
introduces prepare_staticmem_pages to bypass all "pointless work".

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
v8 changes:
- no change
---
v7 changes:
- no change
---
v6 changes:
- adapt to PGC_static
---
v5 changes:
- new commit
---
 xen/common/page_alloc.c | 61 ++++++++++++++++++++++++-----------------
 1 file changed, 36 insertions(+), 25 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index b01272a59a..6112f6a3ed 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2702,26 +2702,13 @@ void free_domstatic_page(struct page_info *page)
         put_domain(d);
 }
 
-/*
- * Acquire nr_mfns contiguous reserved pages, starting at #smfn, of
- * static memory.
- * This function needs to be reworked if used outside of boot.
- */
-static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
-                                                         unsigned long nr_mfns,
-                                                         unsigned int memflags)
+static bool __init prepare_staticmem_pages(struct page_info *pg,
+                                           unsigned long nr_mfns,
+                                           unsigned int memflags)
 {
     bool need_tlbflush = false;
     uint32_t tlbflush_timestamp = 0;
     unsigned long i;
-    struct page_info *pg;
-
-    ASSERT(nr_mfns);
-    for ( i = 0; i < nr_mfns; i++ )
-        if ( !mfn_valid(mfn_add(smfn, i)) )
-            return NULL;
-
-    pg = mfn_to_page(smfn);
 
     spin_lock(&heap_lock);
 
@@ -2732,7 +2719,7 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
         {
             printk(XENLOG_ERR
                    "pg[%lu] Static MFN %"PRI_mfn" c=%#lx t=%#x\n",
-                   i, mfn_x(smfn) + i,
+                   i, mfn_x(page_to_mfn(pg)) + i,
                    pg[i].count_info, pg[i].tlbflush_timestamp);
             goto out_err;
         }
@@ -2756,6 +2743,38 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
     if ( need_tlbflush )
         filtered_flush_tlb_mask(tlbflush_timestamp);
 
+    return true;
+
+ out_err:
+    while ( i-- )
+        pg[i].count_info = PGC_static | PGC_state_free;
+
+    spin_unlock(&heap_lock);
+
+    return false;
+}
+
+/*
+ * Acquire nr_mfns contiguous reserved pages, starting at #smfn, of
+ * static memory.
+ * This function needs to be reworked if used outside of boot.
+ */
+static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
+                                                         unsigned long nr_mfns,
+                                                         unsigned int memflags)
+{
+    unsigned long i;
+    struct page_info *pg;
+
+    ASSERT(nr_mfns);
+    for ( i = 0; i < nr_mfns; i++ )
+        if ( !mfn_valid(mfn_add(smfn, i)) )
+            return NULL;
+
+    pg = mfn_to_page(smfn);
+    if ( !prepare_staticmem_pages(pg, nr_mfns, memflags) )
+        return NULL;
+
     /*
      * Ensure cache and RAM are consistent for platforms where the guest
      * can control its own visibility of/through the cache.
@@ -2764,14 +2783,6 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
         flush_page_to_ram(mfn_x(smfn) + i, !(memflags & MEMF_no_icache_flush));
 
     return pg;
-
- out_err:
-    while ( i-- )
-        pg[i].count_info = PGC_static | PGC_state_free;
-
-    spin_unlock(&heap_lock);
-
-    return NULL;
 }
 
 /*
-- 
2.25.1

[PATCH v8 9/9] xen: retrieve reserved pages on populate_physmap

[Penny Zheng]

When a static domain populates memory through populate_physmap at runtime,
it shall retrieve reserved pages from resv_page_list to make sure that
guest RAM is still restricted in statically configured memory regions.
This commit also introduces a new helper acquire_reserved_page to make it work.

Signed-off-by: Penny Zheng <penny.zheng@arm.com>
---
v8 changes:
- As concurrent free/allocate could modify the resv_page_list, we still
need the lock
---
v7 changes:
- remove the lock, since we add the page to rsv_page_list after it has
been totally freed.
---
v6 changes:
- drop the lock before returning
---
v5 changes:
- 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：
- 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
---
v3 changes:
- move 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:
- 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
---
 xen/common/memory.c     | 23 ++++++++++++++
 xen/common/page_alloc.c | 70 +++++++++++++++++++++++++++++++----------
 xen/include/xen/mm.h    |  1 +
 3 files changed, 77 insertions(+), 17 deletions(-)

diff --git a/xen/common/memory.c b/xen/common/memory.c
index f2d009843a..cb330ce877 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -245,6 +245,29 @@ static void populate_physmap(struct memop_args *a)
 
                 mfn = _mfn(gpfn);
             }
+            else if ( is_domain_using_staticmem(d) )
+            {
+                /*
+                 * No easy way to guarantee the retrieved pages are contiguous,
+                 * so forbid non-zero-order requests here.
+                 */
+                if ( a->extent_order != 0 )
+                {
+                    gdprintk(XENLOG_WARNING,
+                             "Cannot allocate static order-%u pages for static %pd\n",
+                             a->extent_order, d);
+                    goto out;
+                }
+
+                mfn = acquire_reserved_page(d, a->memflags);
+                if ( mfn_eq(mfn, INVALID_MFN) )
+                {
+                    gdprintk(XENLOG_WARNING,
+                             "%pd: failed to retrieve a reserved page\n",
+                             d);
+                    goto out;
+                }
+            }
             else
             {
                 page = alloc_domheap_pages(d, a->extent_order, a->memflags);
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 6112f6a3ed..390a9c002d 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -2702,9 +2702,8 @@ void free_domstatic_page(struct page_info *page)
         put_domain(d);
 }
 
-static bool __init prepare_staticmem_pages(struct page_info *pg,
-                                           unsigned long nr_mfns,
-                                           unsigned int memflags)
+static bool prepare_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
+                                    unsigned int memflags)
 {
     bool need_tlbflush = false;
     uint32_t tlbflush_timestamp = 0;
@@ -2785,21 +2784,9 @@ static struct page_info * __init acquire_staticmem_pages(mfn_t smfn,
     return pg;
 }
 
-/*
- * Acquire nr_mfns contiguous pages, starting at #smfn, of static memory,
- * then assign them to one specific domain #d.
- */
-int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
-                                   unsigned int nr_mfns, unsigned int memflags)
+static int assign_domstatic_pages(struct domain *d, struct page_info *pg,
+                                  unsigned int nr_mfns, unsigned int memflags)
 {
-    struct page_info *pg;
-
-    ASSERT_ALLOC_CONTEXT();
-
-    pg = acquire_staticmem_pages(smfn, nr_mfns, memflags);
-    if ( !pg )
-        return -ENOENT;
-
     if ( !d || (memflags & (MEMF_no_owner | MEMF_no_refcount)) )
     {
         /*
@@ -2818,6 +2805,55 @@ int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
 
     return 0;
 }
+
+/*
+ * Acquire nr_mfns contiguous pages, starting at #smfn, of static memory,
+ * then assign them to one specific domain #d.
+ */
+int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
+                                   unsigned int nr_mfns, unsigned int memflags)
+{
+    struct page_info *pg;
+
+    ASSERT_ALLOC_CONTEXT();
+
+    pg = acquire_staticmem_pages(smfn, nr_mfns, memflags);
+    if ( !pg )
+        return -ENOENT;
+
+    if ( assign_domstatic_pages(d, pg, nr_mfns, memflags) )
+        return -EINVAL;
+
+    return 0;
+}
+
+/*
+ * Acquire a page from reserved page list(resv_page_list), when populating
+ * memory for static domain on runtime.
+ */
+mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags)
+{
+    struct page_info *page;
+
+    /* Acquire a page from reserved page list(resv_page_list). */
+    spin_lock(&d->page_alloc_lock);
+    page = page_list_remove_head(&d->resv_page_list);
+    spin_unlock(&d->page_alloc_lock);
+    if ( unlikely(!page) )
+        return INVALID_MFN;
+
+    if ( !prepare_staticmem_pages(page, 1, memflags) )
+        goto fail;
+
+    if ( assign_domstatic_pages(d, page, 1, memflags) )
+        goto fail;
+
+    return page_to_mfn(page);
+
+ fail:
+    page_list_add_tail(page, &d->resv_page_list);
+    return INVALID_MFN;
+}
 #endif
 
 /*
diff --git a/xen/include/xen/mm.h b/xen/include/xen/mm.h
index 07b8a45f1a..559264b55d 100644
--- a/xen/include/xen/mm.h
+++ b/xen/include/xen/mm.h
@@ -97,6 +97,7 @@ int acquire_domstatic_pages(struct domain *d, mfn_t smfn, unsigned int nr_mfns,
 #else
 #define put_static_page(d, page) ((void)(d), (void)(page))
 #endif
+mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags);
 
 /* Map machine page range in Xen virtual address space. */
 int map_pages_to_xen(
-- 
2.25.1

Re: [PATCH v8 6/9] xen/arm: introduce CDF_staticmem

[Jan Beulich]

On 07.07.2022 11:22, Penny Zheng wrote:
> In order to have an easy and quick way to find out whether this domain memory
> is statically configured, this commit introduces a new flag CDF_staticmem and a
> new helper is_domain_using_staticmem() to tell.
> 
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>

Acked-by: Jan Beulich <jbeulich@suse.com>

Re: [PATCH v8 2/9] xen: do not free reserved memory into heap

[Jan Beulich]

On 07.07.2022 11:22, Penny Zheng wrote:
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -1622,6 +1622,8 @@ void put_page(struct page_info *page)
>  
>      if ( unlikely((nx & PGC_count_mask) == 0) )
>      {
> +        if ( unlikely(nx & PGC_static) )
> +            free_domstatic_page(page);
>          free_domheap_page(page);

Didn't you have "else" there in the proposal you made while discussing
v7? You also don't alter free_domheap_page() to skip static pages.

> @@ -2652,9 +2650,48 @@ void __init free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
>              scrub_one_page(pg);
>          }
>  
> -        /* In case initializing page of static memory, mark it PGC_static. */
>          pg[i].count_info |= PGC_static;
>      }
> +
> +    spin_unlock(&heap_lock);
> +}
> +
> +void free_domstatic_page(struct page_info *page)
> +{
> +    struct domain *d = page_get_owner(page);
> +    bool drop_dom_ref, need_scrub;
> +
> +    ASSERT_ALLOC_CONTEXT();
> +
> +    if ( likely(d) )
> +    {
> +        /* NB. May recursively lock from relinquish_memory(). */
> +        spin_lock_recursive(&d->page_alloc_lock);
> +
> +        arch_free_heap_page(d, page);
> +
> +        /*
> +         * Normally we expect a domain to clear pages before freeing them,
> +         * if it cares about the secrecy of their contents. However, after
> +         * a domain has died we assume responsibility for erasure. We do
> +         * scrub regardless if option scrub_domheap is set.
> +         */
> +        need_scrub = d->is_dying || scrub_debug || opt_scrub_domheap;

May I suggest that instead of copying the comment you simply add
one here referring to the other one? Otoh I'm not sure about the
"dying" case: What happens to a domain's static pages after its
death? Isn't it that they cannot be re-used? If so, scrubbing is
pointless. And whether the other reasons to scrub actually apply
to static pages also isn't quite clear to me.

> +        drop_dom_ref = !domain_adjust_tot_pages(d, -1);
> +
> +        spin_unlock_recursive(&d->page_alloc_lock);
> +    }
> +    else
> +    {
> +        drop_dom_ref = false;
> +        need_scrub = true;
> +    }

Why this "else"? I can't see any way unowned paged would make it here.
Instead you could e.g. have another ASSERT() at the top of the function.

Jan

Re: [PATCH v8 7/9] xen/arm: unpopulate memory when domain is static

[Jan Beulich]

On 07.07.2022 11:22, Penny Zheng wrote:
> @@ -2692,6 +2690,14 @@ void free_domstatic_page(struct page_info *page)
>  
>      free_staticmem_pages(page, 1, need_scrub);
>  
> +    if ( likely(d) )
> +    {
> +        /* Add page on the resv_page_list *after* it has been freed. */
> +        if ( !drop_dom_ref )
> +            put_static_page(d, page);

I'm not happy about this name - it suggests similarity with put_page(),
but is entirely different. But: Do we really need an helper macro here
in the first place? This is static-mem specific code and hence ...

> --- a/xen/include/xen/mm.h
> +++ b/xen/include/xen/mm.h
> @@ -91,6 +91,12 @@ void free_staticmem_pages(struct page_info *pg, unsigned long nr_mfns,
>  void free_domstatic_page(struct page_info *page);
>  int acquire_domstatic_pages(struct domain *d, mfn_t smfn, unsigned int nr_mfns,
>                              unsigned int memflags);
> +#ifdef CONFIG_STATIC_MEMORY
> +#define put_static_page(d, page) \
> +    page_list_add_tail((page), &(d)->resv_page_list)

... this can live right at the use site since ...

> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -381,6 +381,9 @@ struct domain
>      struct page_list_head page_list;  /* linked list */
>      struct page_list_head extra_page_list; /* linked list (size extra_pages) */
>      struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */
> +#ifdef CONFIG_STATIC_MEMORY
> +    struct page_list_head resv_page_list; /* linked list */
> +#endif

... this field is consistently available (i.e. it's all the same config
option that controls things).

Otherwise a nit on the macro: While the parentheses around d are needed,
the ones around page are not.

Jan

Re: [PATCH v8 9/9] xen: retrieve reserved pages on populate_physmap

[Jan Beulich]

On 07.07.2022 11:22, Penny Zheng wrote:
> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -245,6 +245,29 @@ static void populate_physmap(struct memop_args *a)
>  
>                  mfn = _mfn(gpfn);
>              }
> +            else if ( is_domain_using_staticmem(d) )
> +            {
> +                /*
> +                 * No easy way to guarantee the retrieved pages are contiguous,
> +                 * so forbid non-zero-order requests here.
> +                 */
> +                if ( a->extent_order != 0 )
> +                {
> +                    gdprintk(XENLOG_WARNING,
> +                             "Cannot allocate static order-%u pages for static %pd\n",
> +                             a->extent_order, d);

I'm probably wrong in thinking that I did point out before that there's
no real reason to have "static" twice in the message. Or am I mistaken
in my understanding that only static domains can ever have static pages?

> @@ -2818,6 +2805,55 @@ int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
>  
>      return 0;
>  }
> +
> +/*
> + * Acquire nr_mfns contiguous pages, starting at #smfn, of static memory,
> + * then assign them to one specific domain #d.
> + */
> +int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
> +                                   unsigned int nr_mfns, unsigned int memflags)
> +{
> +    struct page_info *pg;
> +
> +    ASSERT_ALLOC_CONTEXT();
> +
> +    pg = acquire_staticmem_pages(smfn, nr_mfns, memflags);
> +    if ( !pg )
> +        return -ENOENT;
> +
> +    if ( assign_domstatic_pages(d, pg, nr_mfns, memflags) )
> +        return -EINVAL;
> +
> +    return 0;
> +}
> +
> +/*
> + * Acquire a page from reserved page list(resv_page_list), when populating
> + * memory for static domain on runtime.
> + */
> +mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags)
> +{
> +    struct page_info *page;

Use ASSERT_ALLOC_CONTEXT() here as well?

> +    /* Acquire a page from reserved page list(resv_page_list). */
> +    spin_lock(&d->page_alloc_lock);
> +    page = page_list_remove_head(&d->resv_page_list);
> +    spin_unlock(&d->page_alloc_lock);
> +    if ( unlikely(!page) )
> +        return INVALID_MFN;
> +
> +    if ( !prepare_staticmem_pages(page, 1, memflags) )
> +        goto fail;

Don't you need to undo what this did if ...

> +    if ( assign_domstatic_pages(d, page, 1, memflags) )
> +        goto fail;

... this fails?

Jan

Re: [PATCH v8 1/9] xen/arm: rename PGC_reserved to PGC_static

[Julien Grall]

Hi Penny,

On 07/07/2022 10:22, Penny Zheng wrote:
> PGC_reserved could be ambiguous, and we have to tell what the pages are
> reserved for, so this commit intends to rename PGC_reserved to
> PGC_static, which clearly indicates the page is reserved for static
> memory.
> 
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> Acked-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Julien Grall <jgrall@amazon.com>

Cheers,

-- 
Julien Grall

Re: [PATCH v8 6/9] xen/arm: introduce CDF_staticmem

[Julien Grall]

Hi Penny,

On 07/07/2022 10:22, Penny Zheng wrote:
> In order to have an easy and quick way to find out whether this domain memory
> is statically configured, this commit introduces a new flag CDF_staticmem and a
> new helper is_domain_using_staticmem() to tell.
> 
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> ---
> v8 changes:
> - #ifdef-ary around is_domain_using_staticmem() is not needed anymore
> ---
> v7 changes:
> - IS_ENABLED(CONFIG_STATIC_MEMORY) would not be needed anymore
> ---
> v6 changes:
> - move non-zero is_domain_using_staticmem() from ARM header to common
> header
> ---
> v5 changes:
> - guard "is_domain_using_staticmem" under CONFIG_STATIC_MEMORY
> - #define is_domain_using_staticmem zero if undefined
> ---
> v4 changes:
> - no changes
> ---
> v3 changes:
> - change name from "is_domain_static()" to "is_domain_using_staticmem"
> ---
> v2 changes:
> - change name from "is_domain_on_static_allocation" to "is_domain_static()"
> ---
>   xen/arch/arm/domain_build.c | 5 ++++-
>   xen/include/xen/domain.h    | 8 ++++++++
>   2 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 3fd1186b53..b76a84e8f5 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -3287,9 +3287,12 @@ void __init create_domUs(void)
>           if ( !dt_device_is_compatible(node, "xen,domain") )
>               continue;
>   
> +        if ( dt_find_property(node, "xen,static-mem", NULL) )
> +            flags |= CDF_staticmem;
> +
>           if ( dt_property_read_bool(node, "direct-map") )
>           {
> -            if ( !IS_ENABLED(CONFIG_STATIC_MEMORY) || !dt_find_property(node, "xen,static-mem", NULL) )

It is not clear to me why dropping IS_ENABLED(...) here is fine. What 
would happen if a user specify "xen,static-mem" in the device-tree but 
forgot CONFIG_STATIC_MEMORY in Xen?

Cheers,

-- 
Julien Grall

Re: [PATCH v8 6/9] xen/arm: introduce CDF_staticmem

[Julien Grall]

On 15/07/2022 19:51, Julien Grall wrote:
> Hi Penny,
> 
> On 07/07/2022 10:22, Penny Zheng wrote:
>> In order to have an easy and quick way to find out whether this domain 
>> memory
>> is statically configured, this commit introduces a new flag 
>> CDF_staticmem and a
>> new helper is_domain_using_staticmem() to tell.
>>
>> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
>> ---
>> v8 changes:
>> - #ifdef-ary around is_domain_using_staticmem() is not needed anymore
>> ---
>> v7 changes:
>> - IS_ENABLED(CONFIG_STATIC_MEMORY) would not be needed anymore
>> ---
>> v6 changes:
>> - move non-zero is_domain_using_staticmem() from ARM header to common
>> header
>> ---
>> v5 changes:
>> - guard "is_domain_using_staticmem" under CONFIG_STATIC_MEMORY
>> - #define is_domain_using_staticmem zero if undefined
>> ---
>> v4 changes:
>> - no changes
>> ---
>> v3 changes:
>> - change name from "is_domain_static()" to "is_domain_using_staticmem"
>> ---
>> v2 changes:
>> - change name from "is_domain_on_static_allocation" to 
>> "is_domain_static()"
>> ---
>>   xen/arch/arm/domain_build.c | 5 ++++-
>>   xen/include/xen/domain.h    | 8 ++++++++
>>   2 files changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index 3fd1186b53..b76a84e8f5 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -3287,9 +3287,12 @@ void __init create_domUs(void)
>>           if ( !dt_device_is_compatible(node, "xen,domain") )
>>               continue;
>> +        if ( dt_find_property(node, "xen,static-mem", NULL) )
>> +            flags |= CDF_staticmem;
>> +
>>           if ( dt_property_read_bool(node, "direct-map") )
>>           {
>> -            if ( !IS_ENABLED(CONFIG_STATIC_MEMORY) || 
>> !dt_find_property(node, "xen,static-mem", NULL) )
> 
> It is not clear to me why dropping IS_ENABLED(...) here is fine. What 
> would happen if a user specify "xen,static-mem" in the device-tree but 
> forgot CONFIG_STATIC_MEMORY in Xen?

Nvm... flags & CDF_staticmem would be 0 so it would cover that case. 
Sorry for the noise.

Acked-by: Julien Grall <jgrall@amazon.com>


Cheers,

-- 
Julien Grall

Re: [PATCH v8 8/9] xen: introduce prepare_staticmem_pages

[Julien Grall]

Hi Penny,

On 07/07/2022 10:22, Penny Zheng wrote:
> Later, we want to use acquire_domstatic_pages() for populating memory
> for static domain on runtime, however, there are a lot of pointless work
> (checking mfn_valid(), scrubbing the free part, cleaning the cache...)
> considering we know the page is valid and belong to the guest.
> 
> This commit splits acquire_staticmem_pages() in two parts, and
> introduces prepare_staticmem_pages to bypass all "pointless work".
> 
> Signed-off-by: Penny Zheng <penny.zheng@arm.com>
> Acked-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Julien Grall <jgrall@amazon.com>

Cheers,

-- 
Julien Grall

RE: [PATCH v8 2/9] xen: do not free reserved memory into heap

[Penny Zheng]

Hi Jan

> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: Friday, July 8, 2022 8:48 PM
> To: Penny Zheng <Penny.Zheng@arm.com>
> Cc: Wei Chen <Wei.Chen@arm.com>; Stefano Stabellini
> <sstabellini@kernel.org>; Julien Grall <julien@xen.org>; Bertrand Marquis
> <Bertrand.Marquis@arm.com>; Volodymyr Babchuk
> <Volodymyr_Babchuk@epam.com>; Andrew Cooper
> <andrew.cooper3@citrix.com>; George Dunlap <george.dunlap@citrix.com>;
> Wei Liu <wl@xen.org>; xen-devel@lists.xenproject.org
> Subject: Re: [PATCH v8 2/9] xen: do not free reserved memory into heap
> 
> On 07.07.2022 11:22, Penny Zheng wrote:
> > --- a/xen/arch/arm/mm.c
> > +++ b/xen/arch/arm/mm.c
> > @@ -1622,6 +1622,8 @@ void put_page(struct page_info *page)
> >
> >      if ( unlikely((nx & PGC_count_mask) == 0) )
> >      {
> > +        if ( unlikely(nx & PGC_static) )
> > +            free_domstatic_page(page);
> >          free_domheap_page(page);
> 
> Didn't you have "else" there in the proposal you made while discussing v7?
> You also don't alter free_domheap_page() to skip static pages.
> 

Yes, "else" is needed

> > @@ -2652,9 +2650,48 @@ void __init free_staticmem_pages(struct
> page_info *pg, unsigned long nr_mfns,
> >              scrub_one_page(pg);
> >          }
> >
> > -        /* In case initializing page of static memory, mark it PGC_static. */
> >          pg[i].count_info |= PGC_static;
> >      }
> > +
> > +    spin_unlock(&heap_lock);
> > +}
> > +
> > +void free_domstatic_page(struct page_info *page) {
> > +    struct domain *d = page_get_owner(page);
> > +    bool drop_dom_ref, need_scrub;
> > +
> > +    ASSERT_ALLOC_CONTEXT();
> > +
> > +    if ( likely(d) )
> > +    {
> > +        /* NB. May recursively lock from relinquish_memory(). */
> > +        spin_lock_recursive(&d->page_alloc_lock);
> > +
> > +        arch_free_heap_page(d, page);
> > +
> > +        /*
> > +         * Normally we expect a domain to clear pages before freeing them,
> > +         * if it cares about the secrecy of their contents. However, after
> > +         * a domain has died we assume responsibility for erasure. We do
> > +         * scrub regardless if option scrub_domheap is set.
> > +         */
> > +        need_scrub = d->is_dying || scrub_debug || opt_scrub_domheap;
> 
> May I suggest that instead of copying the comment you simply add one here
> referring to the other one? Otoh I'm not sure about the "dying" case: What
> happens to a domain's static pages after its death? Isn't it that they cannot
> be re-used? If so, scrubbing is pointless. And whether the other reasons to
> scrub actually apply to static pages also isn't quite clear to me.
> 

Yes, Julien also raised the same question once before while we have been discussing
about how to make the scrubbing static pages asynchronously.

Right now, static memory is either reserved as guest memory or as shared memory,
which both cannot be re-used, so as you said, scrubbing is pointless at the moment.

So here I'll only keep the scrub_debug option, as synchronously scrubbing is already in
free_staticmem_pages.

> > +        drop_dom_ref = !domain_adjust_tot_pages(d, -1);
> > +
> > +        spin_unlock_recursive(&d->page_alloc_lock);
> > +    }
> > +    else
> > +    {
> > +        drop_dom_ref = false;
> > +        need_scrub = true;
> > +    }
> 
> Why this "else"? I can't see any way unowned paged would make it here.
> Instead you could e.g. have another ASSERT() at the top of the function.
> 

True, true. ASSERT(d) will be added

> Jan

RE: [PATCH v8 9/9] xen: retrieve reserved pages on populate_physmap

[Penny Zheng]

Hi Jan

> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: Friday, July 8, 2022 9:06 PM
> To: Penny Zheng <Penny.Zheng@arm.com>
> Cc: Wei Chen <Wei.Chen@arm.com>; Andrew Cooper
> <andrew.cooper3@citrix.com>; George Dunlap <george.dunlap@citrix.com>;
> Julien Grall <julien@xen.org>; Stefano Stabellini <sstabellini@kernel.org>;
> Wei Liu <wl@xen.org>; xen-devel@lists.xenproject.org
> Subject: Re: [PATCH v8 9/9] xen: retrieve reserved pages on
> populate_physmap
> 
> On 07.07.2022 11:22, Penny Zheng wrote:
> > --- a/xen/common/memory.c
> > +++ b/xen/common/memory.c
> > @@ -245,6 +245,29 @@ static void populate_physmap(struct memop_args
> > *a)
> >
> >                  mfn = _mfn(gpfn);
> >              }
> > +            else if ( is_domain_using_staticmem(d) )
> > +            {
> > +                /*
> > +                 * No easy way to guarantee the retrieved pages are contiguous,
> > +                 * so forbid non-zero-order requests here.
> > +                 */
> > +                if ( a->extent_order != 0 )
> > +                {
> > +                    gdprintk(XENLOG_WARNING,
> > +                             "Cannot allocate static order-%u pages for static %pd\n",
> > +                             a->extent_order, d);
> 
> I'm probably wrong in thinking that I did point out before that there's no real
> reason to have "static" twice in the message. Or am I mistaken in my
> understanding that only static domains can ever have static pages?
> 

Sorry for omitting the comment, I'll only keep one static here.
You're right, only static domains can have static pages at the moment.

> > @@ -2818,6 +2805,55 @@ int __init acquire_domstatic_pages(struct
> > domain *d, mfn_t smfn,
> >
> >      return 0;
> >  }
> > +
> > +/*
> > + * Acquire nr_mfns contiguous pages, starting at #smfn, of static
> > +memory,
> > + * then assign them to one specific domain #d.
> > + */
> > +int __init acquire_domstatic_pages(struct domain *d, mfn_t smfn,
> > +                                   unsigned int nr_mfns, unsigned int
> > +memflags) {
> > +    struct page_info *pg;
> > +
> > +    ASSERT_ALLOC_CONTEXT();
> > +
> > +    pg = acquire_staticmem_pages(smfn, nr_mfns, memflags);
> > +    if ( !pg )
> > +        return -ENOENT;
> > +
> > +    if ( assign_domstatic_pages(d, pg, nr_mfns, memflags) )
> > +        return -EINVAL;
> > +
> > +    return 0;
> > +}
> > +
> > +/*
> > + * Acquire a page from reserved page list(resv_page_list), when
> > +populating
> > + * memory for static domain on runtime.
> > + */
> > +mfn_t acquire_reserved_page(struct domain *d, unsigned int memflags)
> > +{
> > +    struct page_info *page;
> 
> Use ASSERT_ALLOC_CONTEXT() here as well?
> 

Sure,

> > +    /* Acquire a page from reserved page list(resv_page_list). */
> > +    spin_lock(&d->page_alloc_lock);
> > +    page = page_list_remove_head(&d->resv_page_list);
> > +    spin_unlock(&d->page_alloc_lock);
> > +    if ( unlikely(!page) )
> > +        return INVALID_MFN;
> > +
> > +    if ( !prepare_staticmem_pages(page, 1, memflags) )
> > +        goto fail;
> 
> Don't you need to undo what this did if ...
> 
> > +    if ( assign_domstatic_pages(d, page, 1, memflags) )
> > +        goto fail;
> 
> ... this fails?

Yes, thanks for pointing out.
free_staticmem_pages is needed to do the reversal when it fails

> 
> Jan