---
Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Changes in v2:
- Add Andrew's acked-by
---
xen/arch/x86/mm/p2m-pod.c | 154 ++++++++++++++++++++++++++++++----------------
1 file changed, 102 insertions(+), 52 deletions(-)
diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c
index 1f07441259..6f045081b5 100644
--- a/xen/arch/x86/mm/p2m-pod.c
+++ b/xen/arch/x86/mm/p2m-pod.c
@@ -155,8 +155,10 @@ static struct page_info * p2m_pod_cache_get(struct
p2m_domain *p2m,
BUG_ON( page_list_empty(&p2m->pod.super) );
- /* Break up a superpage to make single pages. NB count doesn't
- * need to be adjusted. */
+ /*
+ * Break up a superpage to make single pages. NB count doesn't
+ * need to be adjusted.
+ */
p = page_list_remove_head(&p2m->pod.super);
mfn = mfn_x(page_to_mfn(p));
@@ -242,8 +244,10 @@ p2m_pod_set_cache_target(struct p2m_domain *p2m, unsigned long pod_target, int p
}
/* Decreasing the target */
- /* We hold the pod lock here, so we don't need to worry about
- * cache disappearing under our feet. */
+ /*
+ * We hold the pod lock here, so we don't need to worry about
+ * cache disappearing under our feet.
+ */
while ( pod_target < p2m->pod.count )
{
struct page_info * page;
@@ -345,15 +349,19 @@ p2m_pod_set_mem_target(struct domain *d, unsigned long
target)
if ( d->is_dying )
goto out;
- /* T' < B: Don't reduce the cache size; let the balloon driver
- * take care of it. */
+ /*
+ * T' < B: Don't reduce the cache size; let the balloon driver
+ * take care of it.
+ */
if ( target < d->tot_pages )
goto out;
pod_target = target - populated;
- /* B < T': Set the cache size equal to # of outstanding entries,
- * let the balloon driver fill in the rest. */
+ /*
+ * B < T': Set the cache size equal to # of outstanding entries,
+ * let the balloon driver fill in the rest.
+ */
if ( populated > 0 && pod_target > p2m->pod.entry_count )
pod_target = p2m->pod.entry_count;
@@ -491,7 +499,8 @@ static int
p2m_pod_zero_check_superpage(struct p2m_domain *p2m, unsigned long gfn);
-/* This function is needed for two reasons:
+/*
+ * This function is needed for two reasons:
* + To properly handle clearing of PoD entries
* + To "steal back" memory being freed for the PoD cache, rather than
* releasing it.
@@ -513,8 +522,10 @@ p2m_pod_decrease_reservation(struct domain *d,
gfn_lock(p2m, gpfn, order);
pod_lock(p2m);
- /* If we don't have any outstanding PoD entries, let things take their
- * course */
+ /*
+ * If we don't have any outstanding PoD entries, let things take their
+ * course.
+ */
if ( p2m->pod.entry_count == 0 )
goto out_unlock;
@@ -550,8 +561,10 @@ p2m_pod_decrease_reservation(struct domain *d,
if ( !nonpod )
{
- /* All PoD: Mark the whole region invalid and tell caller
- * we're done. */
+ /*
+ * All PoD: Mark the whole region invalid and tell caller
+ * we're done.
+ */
p2m_set_entry(p2m, gpfn, INVALID_MFN, order, p2m_invalid,
p2m->default_access);
p2m->pod.entry_count-=(1<<order);
@@ -568,15 +581,16 @@ p2m_pod_decrease_reservation(struct domain *d,
* - order >= SUPERPAGE_ORDER (the loop below will take care of this)
* - not all of the pages were RAM (now knowing order < SUPERPAGE_ORDER)
*/
- if ( steal_for_cache && order < SUPERPAGE_ORDER && ram == (1 << order) &&
+ if ( steal_for_cache && order < SUPERPAGE_ORDER && ram == (1UL << order) &&
p2m_pod_zero_check_superpage(p2m, gpfn & ~(SUPERPAGE_PAGES - 1)) )
{
- pod = 1 << order;
+ pod = 1UL << order;
ram = nonpod = 0;
ASSERT(steal_for_cache == (p2m->pod.entry_count > p2m->pod.count));
}
- /* Process as long as:
+ /*
+ * Process as long as:
* + There are PoD entries to handle, or
* + There is ram left, and we want to steal it
*/
@@ -631,8 +645,10 @@ p2m_pod_decrease_reservation(struct domain *d,
}
}
- /* If there are no more non-PoD entries, tell decrease_reservation() that
- * there's nothing left to do. */
+ /*
+ * If there are no more non-PoD entries, tell decrease_reservation() that
+ * there's nothing left to do.
+ */
if ( nonpod == 0 )
ret = 1;
@@ -658,9 +674,11 @@ void p2m_pod_dump_data(struct domain *d)
}
-/* Search for all-zero superpages to be reclaimed as superpages for the
+/*
+ * Search for all-zero superpages to be reclaimed as superpages for the
* PoD cache. Must be called w/ pod lock held, must lock the superpage
- * in the p2m */
+ * in the p2m.
+ */
static int
p2m_pod_zero_check_superpage(struct p2m_domain *p2m, unsigned long gfn)
{
@@ -682,12 +700,16 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m,
unsigned long gfn)
if ( paging_mode_shadow(d) )
max_ref++;
- /* NOTE: this is why we don't enforce deadlock constraints between p2m
- * and pod locks */
+ /*
+ * NOTE: this is why we don't enforce deadlock constraints between p2m
+ * and pod locks.
+ */
gfn_lock(p2m, gfn, SUPERPAGE_ORDER);
- /* Look up the mfns, checking to make sure they're the same mfn
- * and aligned, and mapping them. */
+ /*
+ * Look up the mfns, checking to make sure they're the same mfn
+ * and aligned, and mapping them.
+ */
for ( i = 0; i < SUPERPAGE_PAGES; i += n )
{
p2m_access_t a;
@@ -697,7 +719,8 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m,
unsigned long gfn)
mfn = p2m->get_entry(p2m, gfn + i, &type, &a, 0, &cur_order, NULL);
- /* Conditions that must be met for superpage-superpage:
+ /*
+ * Conditions that must be met for superpage-superpage:
* + All gfns are ram types
* + All gfns have the same type
* + All of the mfns are allocated to a domain
@@ -751,9 +774,11 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m,
unsigned long gfn)
p2m_populate_on_demand, p2m->default_access);
p2m_tlb_flush_sync(p2m);
- /* Make none of the MFNs are used elsewhere... for example, mapped
+ /*
+ * Make none of the MFNs are used elsewhere... for example, mapped
* via the grant table interface, or by qemu. Allow one refcount for
- * being allocated to the domain. */
+ * being allocated to the domain.
+ */
for ( i=0; i < SUPERPAGE_PAGES; i++ )
{
mfn = _mfn(mfn_x(mfn0) + i);
@@ -797,8 +822,10 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m,
unsigned long gfn)
__trace_var(TRC_MEM_POD_ZERO_RECLAIM, 0, sizeof(t), &t);
}
- /* Finally! We've passed all the checks, and can add the mfn superpage
- * back on the PoD cache, and account for the new p2m PoD entries */
+ /*
+ * Finally! We've passed all the checks, and can add the mfn superpage
+ * back on the PoD cache, and account for the new p2m PoD entries.
+ */
p2m_pod_cache_add(p2m, mfn_to_page(mfn0), PAGE_ORDER_2M);
p2m->pod.entry_count += SUPERPAGE_PAGES;
@@ -833,8 +860,10 @@ p2m_pod_zero_check(struct p2m_domain *p2m, unsigned long *gfns, int count)
{
p2m_access_t a;
mfns[i] = p2m->get_entry(p2m, gfns[i], types + i, &a, 0, NULL, NULL);
- /* If this is ram, and not a pagetable or from the xen heap, and
probably not mapped
- elsewhere, map it; otherwise, skip. */
+ /*
+ * If this is ram, and not a pagetable or from the xen heap, and
+ * probably not mapped elsewhere, map it; otherwise, skip.
+ */
if ( p2m_is_ram(types[i])
&& ( (mfn_to_page(mfns[i])->count_info & PGC_allocated) != 0 )
&& ( (mfn_to_page(mfns[i])->count_info &
(PGC_page_table|PGC_xen_heap)) == 0 )
@@ -844,8 +873,10 @@ p2m_pod_zero_check(struct p2m_domain *p2m, unsigned long
*gfns, int count)
map[i] = NULL;
}
- /* Then, go through and check for zeroed pages, removing write permission
- * for those with zeroes. */
+ /*
+ * Then, go through and check for zeroed pages, removing write permission
+ * for those with zeroes.
+ */
for ( i=0; i<count; i++ )
{
if(!map[i])
@@ -867,8 +898,10 @@ p2m_pod_zero_check(struct p2m_domain *p2m, unsigned long
*gfns, int count)
p2m_set_entry(p2m, gfns[i], INVALID_MFN, PAGE_ORDER_4K,
p2m_populate_on_demand, p2m->default_access);
- /* See if the page was successfully unmapped. (Allow one refcount
- * for being allocated to a domain.) */
+ /*
+ * See if the page was successfully unmapped. (Allow one refcount
+ * for being allocated to a domain.)
+ */
if ( (mfn_to_page(mfns[i])->count_info & PGC_count_mask) > 1 )
{
unmap_domain_page(map[i]);
@@ -895,8 +928,10 @@ p2m_pod_zero_check(struct p2m_domain *p2m, unsigned long
*gfns, int count)
unmap_domain_page(map[i]);
- /* See comment in p2m_pod_zero_check_superpage() re gnttab
- * check timing. */
+ /*
+ * See comment in p2m_pod_zero_check_superpage() re gnttab
+ * check timing.
+ */
if ( j < PAGE_SIZE/sizeof(*map[i]) )
{
p2m_set_entry(p2m, gfns[i], mfns[i], PAGE_ORDER_4K,
@@ -944,9 +979,11 @@ p2m_pod_emergency_sweep(struct p2m_domain *p2m)
limit = (start > POD_SWEEP_LIMIT) ? (start - POD_SWEEP_LIMIT) : 0;
/* FIXME: Figure out how to avoid superpages */
- /* NOTE: Promote to globally locking the p2m. This will get complicated
+ /*
+ * NOTE: Promote to globally locking the p2m. This will get complicated
* in a fine-grained scenario. If we lock each gfn individually we must be
- * careful about spinlock recursion limits and POD_SWEEP_STRIDE. */
+ * careful about spinlock recursion limits and POD_SWEEP_STRIDE.
+ */
p2m_lock(p2m);
for ( i=p2m->pod.reclaim_single; i > 0 ; i-- )
{
@@ -963,11 +1000,13 @@ p2m_pod_emergency_sweep(struct p2m_domain *p2m)
j = 0;
}
}
- /* Stop if we're past our limit and we have found *something*.
+ /*
+ * Stop if we're past our limit and we have found *something*.
*
* NB that this is a zero-sum game; we're increasing our cache size
* by re-increasing our 'debt'. Since we hold the pod lock,
- * (entry_count - count) must remain the same. */
+ * (entry_count - count) must remain the same.
+ */
if ( i < limit && (p2m->pod.count > 0 || hypercall_preempt_check()) )
break;
}
@@ -1045,20 +1084,25 @@ p2m_pod_demand_populate(struct p2m_domain *p2m,
unsigned long gfn,
ASSERT(gfn_locked_by_me(p2m, gfn));
pod_lock(p2m);
- /* This check is done with the pod lock held. This will make sure that
+ /*
+ * This check is done with the pod lock held. This will make sure that
* even if d->is_dying changes under our feet, p2m_pod_empty_cache()
- * won't start until we're done. */
+ * won't start until we're done.
+ */
if ( unlikely(d->is_dying) )
goto out_fail;
- /* Because PoD does not have cache list for 1GB pages, it has to remap
- * 1GB region to 2MB chunks for a retry. */
+ /*
+ * Because PoD does not have cache list for 1GB pages, it has to remap
+ * 1GB region to 2MB chunks for a retry.
+ */
if ( order == PAGE_ORDER_1G )
{
pod_unlock(p2m);
gfn_aligned = (gfn >> order) << order;
- /* Note that we are supposed to call p2m_set_entry() 512 times to
+ /*
+ * Note that we are supposed to call p2m_set_entry() 512 times to
* split 1GB into 512 2MB pages here. But We only do once here because
* p2m_set_entry() should automatically shatter the 1GB page into
* 512 2MB pages. The rest of 511 calls are unnecessary.
@@ -1075,8 +1119,10 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned
long gfn,
if ( p2m->pod.entry_count > p2m->pod.count )
pod_eager_reclaim(p2m);
- /* Only sweep if we're actually out of memory. Doing anything else
- * causes unnecessary time and fragmentation of superpages in the p2m. */
+ /*
+ * Only sweep if we're actually out of memory. Doing anything else
+ * causes unnecessary time and fragmentation of superpages in the p2m.
+ */
if ( p2m->pod.count == 0 )
p2m_pod_emergency_sweep(p2m);
@@ -1088,8 +1134,10 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, unsigned long gfn,
if ( gfn > p2m->pod.max_guest )
p2m->pod.max_guest = gfn;
- /* Get a page f/ the cache. A NULL return value indicates that the
- * 2-meg range should be marked singleton PoD, and retried */
+ /*
+ * Get a page f/ the cache. A NULL return value indicates that the
+ * 2-meg range should be marked singleton PoD, and retried.
+ */
if ( (p = p2m_pod_cache_get(p2m, order)) == NULL )
goto remap_and_retry;
@@ -1146,8 +1194,10 @@ remap_and_retry:
pod_unlock(p2m);
/* Remap this 2-meg region in singleton chunks */
- /* NOTE: In a p2m fine-grained lock scenario this might
- * need promoting the gfn lock from gfn->2M superpage */
+ /*
+ * NOTE: In a p2m fine-grained lock scenario this might
+ * need promoting the gfn lock from gfn->2M superpage.
+ */
gfn_aligned = (gfn>>order)<<order;
for(i=0; i<(1<<order); i++)
p2m_set_entry(p2m, gfn_aligned + i, INVALID_MFN, PAGE_ORDER_4K,
