[Xen-devel] [PATCH v8 2/4] add a domain_tot_pages() helper function

[Paul Durrant <pdurrant@amazon.com>]

This patch adds a new domain_tot_pages() inline helper function into
sched.h, which will be needed by a subsequent patch.

No functional change.

NOTE: While modifying the comment for 'tot_pages' in sched.h this patch
      makes some cosmetic fixes to surrounding comments.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Paul Durrant <pdurrant@amazon.com>
---
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Wei Liu <wl@xen.org>
Cc: "Roger Pau Monné" <roger.pau@citrix.com>
Cc: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Julien Grall <julien@xen.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Tim Deegan <tim@xen.org>

v8:
 - New in v8
---
 xen/arch/x86/domain.c           |  2 +-
 xen/arch/x86/mm.c               |  6 +++---
 xen/arch/x86/mm/p2m-pod.c       | 10 +++++-----
 xen/arch/x86/mm/shadow/common.c |  2 +-
 xen/arch/x86/msi.c              |  2 +-
 xen/arch/x86/numa.c             |  2 +-
 xen/arch/x86/pv/dom0_build.c    | 25 +++++++++++++------------
 xen/arch/x86/pv/domain.c        |  2 +-
 xen/common/domctl.c             |  2 +-
 xen/common/grant_table.c        |  4 ++--
 xen/common/keyhandler.c         |  2 +-
 xen/common/memory.c             |  4 ++--
 xen/common/page_alloc.c         | 15 ++++++++-------
 xen/include/public/memory.h     |  4 ++--
 xen/include/xen/sched.h         | 24 ++++++++++++++++++------
 15 files changed, 60 insertions(+), 46 deletions(-)

diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 28fefa1f81..643c23ffb0 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -218,7 +218,7 @@ void dump_pageframe_info(struct domain *d)
 
     printk("Memory pages belonging to domain %u:\n", d->domain_id);
 
-    if ( d->tot_pages >= 10 && d->is_dying < DOMDYING_dead )
+    if ( domain_tot_pages(d) >= 10 && d->is_dying < DOMDYING_dead )
     {
         printk("    DomPage list too long to display\n");
     }
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index f50c065af3..8bb66cf30c 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4194,8 +4194,8 @@ long do_mmu_update(
  * - page caching attributes cleaned up
  * - removed from the domain's page_list
  *
- * If MEMF_no_refcount is not set, the domain's tot_pages will be
- * adjusted.  If this results in the page count falling to 0,
+ * If MEMF_no_refcount is not set, the domain_adjust_tot_pages() will
+ * be called.  If this results in the page count falling to 0,
  * put_domain() will be called.
  *
  * The caller should either call free_domheap_page() to free the
@@ -4870,7 +4870,7 @@ long arch_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         else if ( rc >= 0 )
         {
             p2m = p2m_get_hostp2m(d);
-            target.tot_pages       = d->tot_pages;
+            target.tot_pages       = domain_tot_pages(d);
             target.pod_cache_pages = p2m->pod.count;
             target.pod_entries     = p2m->pod.entry_count;
 
diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index 096e2773fb..f2c9409568 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -302,7 +302,7 @@ out:
  * The following equations should hold:
  *  0 <= P <= T <= B <= M
  *  d->arch.p2m->pod.entry_count == B - P
- *  d->tot_pages == P + d->arch.p2m->pod.count
+ *  domain_tot_pages(d) == P + d->arch.p2m->pod.count
  *
  * Now we have the following potential cases to cover:
  *     B <T': Set the PoD cache size equal to the number of outstanding PoD
@@ -336,7 +336,7 @@ p2m_pod_set_mem_target(struct domain *d, unsigned long target)
     pod_lock(p2m);
 
     /* P == B: Nothing to do (unless the guest is being created). */
-    populated = d->tot_pages - p2m->pod.count;
+    populated = domain_tot_pages(d) - p2m->pod.count;
     if ( populated > 0 && p2m->pod.entry_count == 0 )
         goto out;
 
@@ -348,7 +348,7 @@ p2m_pod_set_mem_target(struct domain *d, unsigned long target)
      * T' < B: Don't reduce the cache size; let the balloon driver
      * take care of it.
      */
-    if ( target < d->tot_pages )
+    if ( target < domain_tot_pages(d) )
         goto out;
 
     pod_target = target - populated;
@@ -1231,8 +1231,8 @@ out_of_memory:
     pod_unlock(p2m);
 
     printk("%s: Dom%d out of PoD memory! (tot=%"PRIu32" ents=%ld dom%d)\n",
-           __func__, d->domain_id, d->tot_pages, p2m->pod.entry_count,
-           current->domain->domain_id);
+           __func__, d->domain_id, domain_tot_pages(d),
+           p2m->pod.entry_count, current->domain->domain_id);
     domain_crash(d);
     return false;
 out_fail:
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index 6212ec2c4a..cba3ab1eba 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -1256,7 +1256,7 @@ static unsigned int sh_min_allocation(const struct domain *d)
      * up of slot zero and an LAPIC page), plus one for HVM's 1-to-1 pagetable.
      */
     return shadow_min_acceptable_pages(d) +
-           max(max(d->tot_pages / 256,
+           max(max(domain_tot_pages(d) / 256,
                    is_hvm_domain(d) ? CONFIG_PAGING_LEVELS + 2 : 0U) +
                is_hvm_domain(d),
                d->arch.paging.shadow.p2m_pages);
diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c
index df97ce0c72..2fabaaa155 100644
--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -991,7 +991,7 @@ static int msix_capability_init(struct pci_dev *dev,
                        seg, bus, slot, func, d->domain_id);
             if ( !is_hardware_domain(d) &&
                  /* Assume a domain without memory has no mappings yet. */
-                 (!is_hardware_domain(currd) || d->tot_pages) )
+                 (!is_hardware_domain(currd) || domain_tot_pages(d)) )
                 domain_crash(d);
             /* XXX How to deal with existing mappings? */
         }
diff --git a/xen/arch/x86/numa.c b/xen/arch/x86/numa.c
index 7e1f563012..7f0d27c153 100644
--- a/xen/arch/x86/numa.c
+++ b/xen/arch/x86/numa.c
@@ -419,7 +419,7 @@ static void dump_numa(unsigned char key)
     {
         process_pending_softirqs();
 
-        printk("Domain %u (total: %u):\n", d->domain_id, d->tot_pages);
+        printk("Domain %u (total: %u):\n", d->domain_id, domain_tot_pages(d));
 
         for_each_online_node ( i )
             page_num_node[i] = 0;
diff --git a/xen/arch/x86/pv/dom0_build.c b/xen/arch/x86/pv/dom0_build.c
index 9a97cf4abf..5678da782d 100644
--- a/xen/arch/x86/pv/dom0_build.c
+++ b/xen/arch/x86/pv/dom0_build.c
@@ -110,8 +110,9 @@ static __init void setup_pv_physmap(struct domain *d, unsigned long pgtbl_pfn,
 
     while ( vphysmap_start < vphysmap_end )
     {
-        if ( d->tot_pages + ((round_pgup(vphysmap_end) - vphysmap_start)
-                             >> PAGE_SHIFT) + 3 > nr_pages )
+        if ( domain_tot_pages(d) +
+             ((round_pgup(vphysmap_end) - vphysmap_start) >> PAGE_SHIFT) +
+             3 > nr_pages )
             panic("Dom0 allocation too small for initial P->M table\n");
 
         if ( pl1e )
@@ -264,7 +265,7 @@ static struct page_info * __init alloc_chunk(struct domain *d,
     {
         struct page_info *pg2;
 
-        if ( d->tot_pages + (1 << order) > d->max_pages )
+        if ( domain_tot_pages(d) + (1 << order) > d->max_pages )
             continue;
         pg2 = alloc_domheap_pages(d, order, MEMF_exact_node | MEMF_no_scrub);
         if ( pg2 > page )
@@ -500,13 +501,13 @@ int __init dom0_construct_pv(struct domain *d,
     if ( page == NULL )
         panic("Not enough RAM for domain 0 allocation\n");
     alloc_spfn = mfn_x(page_to_mfn(page));
-    alloc_epfn = alloc_spfn + d->tot_pages;
+    alloc_epfn = alloc_spfn + domain_tot_pages(d);
 
     if ( initrd_len )
     {
         initrd_pfn = vinitrd_start ?
                      (vinitrd_start - v_start) >> PAGE_SHIFT :
-                     d->tot_pages;
+                     domain_tot_pages(d);
         initrd_mfn = mfn = initrd->mod_start;
         count = PFN_UP(initrd_len);
         if ( d->arch.physaddr_bitsize &&
@@ -541,9 +542,9 @@ int __init dom0_construct_pv(struct domain *d,
     printk("PHYSICAL MEMORY ARRANGEMENT:\n"
            " Dom0 alloc.:   %"PRIpaddr"->%"PRIpaddr,
            pfn_to_paddr(alloc_spfn), pfn_to_paddr(alloc_epfn));
-    if ( d->tot_pages < nr_pages )
+    if ( domain_tot_pages(d) < nr_pages )
         printk(" (%lu pages to be allocated)",
-               nr_pages - d->tot_pages);
+               nr_pages - domain_tot_pages(d));
     if ( initrd )
     {
         mpt_alloc = (paddr_t)initrd->mod_start << PAGE_SHIFT;
@@ -755,7 +756,7 @@ int __init dom0_construct_pv(struct domain *d,
     snprintf(si->magic, sizeof(si->magic), "xen-3.0-x86_%d%s",
              elf_64bit(&elf) ? 64 : 32, parms.pae ? "p" : "");
 
-    count = d->tot_pages;
+    count = domain_tot_pages(d);
 
     /* Set up the phys->machine table if not part of the initial mapping. */
     if ( parms.p2m_base != UNSET_ADDR )
@@ -786,7 +787,7 @@ int __init dom0_construct_pv(struct domain *d,
             process_pending_softirqs();
     }
     si->first_p2m_pfn = pfn;
-    si->nr_p2m_frames = d->tot_pages - count;
+    si->nr_p2m_frames = domain_tot_pages(d) - count;
     page_list_for_each ( page, &d->page_list )
     {
         mfn = mfn_x(page_to_mfn(page));
@@ -804,15 +805,15 @@ int __init dom0_construct_pv(struct domain *d,
                 process_pending_softirqs();
         }
     }
-    BUG_ON(pfn != d->tot_pages);
+    BUG_ON(pfn != domain_tot_pages(d));
 #ifndef NDEBUG
     alloc_epfn += PFN_UP(initrd_len) + si->nr_p2m_frames;
 #endif
     while ( pfn < nr_pages )
     {
-        if ( (page = alloc_chunk(d, nr_pages - d->tot_pages)) == NULL )
+        if ( (page = alloc_chunk(d, nr_pages - domain_tot_pages(d))) == NULL )
             panic("Not enough RAM for DOM0 reservation\n");
-        while ( pfn < d->tot_pages )
+        while ( pfn < domain_tot_pages(d) )
         {
             mfn = mfn_x(page_to_mfn(page));
 #ifndef NDEBUG
diff --git a/xen/arch/x86/pv/domain.c b/xen/arch/x86/pv/domain.c
index 4da0b2afff..c95652d1b8 100644
--- a/xen/arch/x86/pv/domain.c
+++ b/xen/arch/x86/pv/domain.c
@@ -173,7 +173,7 @@ int switch_compat(struct domain *d)
 
     BUILD_BUG_ON(offsetof(struct shared_info, vcpu_info) != 0);
 
-    if ( is_hvm_domain(d) || d->tot_pages != 0 )
+    if ( is_hvm_domain(d) || domain_tot_pages(d) != 0 )
         return -EACCES;
     if ( is_pv_32bit_domain(d) )
         return 0;
diff --git a/xen/common/domctl.c b/xen/common/domctl.c
index 8b819f56e5..bdc24bbd7c 100644
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -191,7 +191,7 @@ void getdomaininfo(struct domain *d, struct xen_domctl_getdomaininfo *info)
 
     xsm_security_domaininfo(d, info);
 
-    info->tot_pages         = d->tot_pages;
+    info->tot_pages         = domain_tot_pages(d);
     info->max_pages         = d->max_pages;
     info->outstanding_pages = d->outstanding_pages;
     info->shr_pages         = atomic_read(&d->shr_pages);
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
index 5536d282b9..8bee6b3b66 100644
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -2261,7 +2261,7 @@ gnttab_transfer(
          * pages when it is dying.
          */
         if ( unlikely(e->is_dying) ||
-             unlikely(e->tot_pages >= e->max_pages) )
+             unlikely(domain_tot_pages(e) >= e->max_pages) )
         {
             spin_unlock(&e->page_alloc_lock);
 
@@ -2271,7 +2271,7 @@ gnttab_transfer(
             else
                 gdprintk(XENLOG_INFO,
                          "Transferee d%d has no headroom (tot %u, max %u)\n",
-                         e->domain_id, e->tot_pages, e->max_pages);
+                         e->domain_id, domain_tot_pages(e), e->max_pages);
 
             gop.status = GNTST_general_error;
             goto unlock_and_copyback;
diff --git a/xen/common/keyhandler.c b/xen/common/keyhandler.c
index f50490d0f3..87bd145374 100644
--- a/xen/common/keyhandler.c
+++ b/xen/common/keyhandler.c
@@ -271,7 +271,7 @@ static void dump_domains(unsigned char key)
                atomic_read(&d->pause_count));
         printk("    nr_pages=%d xenheap_pages=%d shared_pages=%u paged_pages=%u "
                "dirty_cpus={%*pbl} max_pages=%u\n",
-               d->tot_pages, d->xenheap_pages, atomic_read(&d->shr_pages),
+               domain_tot_pages(d), d->xenheap_pages, atomic_read(&d->shr_pages),
                atomic_read(&d->paged_pages), CPUMASK_PR(d->dirty_cpumask),
                d->max_pages);
         printk("    handle=%02x%02x%02x%02x-%02x%02x-%02x%02x-"
diff --git a/xen/common/memory.c b/xen/common/memory.c
index c7d2bac452..bf464e8799 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -717,7 +717,7 @@ static long memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) arg)
 
                 /*
                  * Pages in in_chunk_list is stolen without
-                 * decreasing the tot_pages. If the domain is dying when
+                 * decreasing domain_tot_pages(). If the domain is dying when
                  * assign pages, we need decrease the count. For those pages
                  * that has been assigned, it should be covered by
                  * domain_relinquish_resources().
@@ -1267,7 +1267,7 @@ long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         switch ( op )
         {
         case XENMEM_current_reservation:
-            rc = d->tot_pages;
+            rc = domain_tot_pages(d);
             break;
         case XENMEM_maximum_reservation:
             rc = d->max_pages;
diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index 919a270587..bbd3163909 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -518,8 +518,8 @@ int domain_set_outstanding_pages(struct domain *d, unsigned long pages)
         goto out;
     }
 
-    /* disallow a claim not exceeding current tot_pages or above max_pages */
-    if ( (pages <= d->tot_pages) || (pages > d->max_pages) )
+    /* disallow a claim not exceeding domain_tot_pages() or above max_pages */
+    if ( (pages <= domain_tot_pages(d)) || (pages > d->max_pages) )
     {
         ret = -EINVAL;
         goto out;
@@ -532,9 +532,9 @@ int domain_set_outstanding_pages(struct domain *d, unsigned long pages)
 
     /*
      * Note, if domain has already allocated memory before making a claim
-     * then the claim must take tot_pages into account
+     * then the claim must take domain_tot_pages() into account
      */
-    claim = pages - d->tot_pages;
+    claim = pages - domain_tot_pages(d);
     if ( claim > avail_pages )
         goto out;
 
@@ -2269,11 +2269,12 @@ int assign_pages(
 
     if ( !(memflags & MEMF_no_refcount) )
     {
-        if ( unlikely((d->tot_pages + (1 << order)) > d->max_pages) )
+        unsigned int tot_pages = domain_tot_pages(d) + (1 << order);
+
+        if ( unlikely(tot_pages > d->max_pages) )
         {
             gprintk(XENLOG_INFO, "Over-allocation for domain %u: "
-                    "%u > %u\n", d->domain_id,
-                    d->tot_pages + (1 << order), d->max_pages);
+                    "%u > %u\n", d->domain_id, tot_pages, d->max_pages);
             rc = -E2BIG;
             goto out;
         }
diff --git a/xen/include/public/memory.h b/xen/include/public/memory.h
index cfdda6e2a8..126d0ff06e 100644
--- a/xen/include/public/memory.h
+++ b/xen/include/public/memory.h
@@ -553,8 +553,8 @@ DEFINE_XEN_GUEST_HANDLE(xen_mem_sharing_op_t);
  *
  * Note that a valid claim may be staked even after memory has been
  * allocated for a domain.  In this case, the claim is not incremental,
- * i.e. if the domain's tot_pages is 3, and a claim is staked for 10,
- * only 7 additional pages are claimed.
+ * i.e. if the domain's total page count is 3, and a claim is staked
+ * for 10, only 7 additional pages are claimed.
  *
  * Caller must be privileged or the hypercall fails.
  */
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 7c5c437247..1b6d7b941f 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -364,12 +364,18 @@ struct domain
     spinlock_t       page_alloc_lock; /* protects all the following fields  */
     struct page_list_head page_list;  /* linked list */
     struct page_list_head xenpage_list; /* linked list (size xenheap_pages) */
-    unsigned int     tot_pages;       /* number of pages currently possesed */
-    unsigned int     xenheap_pages;   /* # pages allocated from Xen heap    */
-    unsigned int     outstanding_pages; /* pages claimed but not possessed  */
-    unsigned int     max_pages;       /* maximum value for tot_pages        */
-    atomic_t         shr_pages;       /* number of shared pages             */
-    atomic_t         paged_pages;     /* number of paged-out pages          */
+
+    /*
+     * This field should only be directly accessed by domain_adjust_tot_pages()
+     * and the domain_tot_pages() helper function defined below.
+     */
+    unsigned int     tot_pages;
+
+    unsigned int     xenheap_pages;     /* pages allocated from Xen heap */
+    unsigned int     outstanding_pages; /* pages claimed but not possessed */
+    unsigned int     max_pages;         /* maximum value for domain_tot_pages() */
+    atomic_t         shr_pages;         /* shared pages */
+    atomic_t         paged_pages;       /* paged-out pages */
 
     /* Scheduling. */
     void            *sched_priv;    /* scheduler-specific data */
@@ -539,6 +545,12 @@ struct domain
 #endif
 };
 
+/* Return number of pages currently posessed by the domain */
+static inline unsigned int domain_tot_pages(const struct domain *d)
+{
+    return d->tot_pages;
+}
+
 /* Protect updates/reads (resp.) of domain_list and domain_hash. */
 extern spinlock_t domlist_update_lock;
 extern rcu_read_lock_t domlist_read_lock;
-- 
2.20.1


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