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x86/PoD: shorten certain operations on higher order ranges

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Now that p2m->get_entry() always returns a valid order, utilize this
to accelerate some of the operations in PoD code. (There are two uses
of p2m->get_entry() left which don't easily lend themselves to this
optimization.)

Also adjust a few types as needed and remove stale comments from
p2m_pod_cache_add() (to avoid duplicating them yet another time).

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
This commit is contained in:
Jan Beulich committed 2015-10-02 13:42:01 +02:00
1 parent edb9531263
commit 3c352011c0
1 file changed
+78 -52
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xen/arch/x86/mm/p2m-pod.c
+78 -52
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@@ -119,20 +119,23 @@ p2m_pod_cache_add(struct p2m_domain *p2m,
unlock_page_alloc(p2m);
/* Then add the first one to the appropriate populate-on-demand list */
switch(order)
/* Then add to the appropriate populate-on-demand list. */
switch ( order )
{
case PAGE_ORDER_1G:
for ( i = 0; i < (1UL << PAGE_ORDER_1G); i += 1UL << PAGE_ORDER_2M )
page_list_add_tail(page + i, &p2m->pod.super);
break;
case PAGE_ORDER_2M:
page_list_add_tail(page, &p2m->pod.super); /* lock: page_alloc */
p2m->pod.count += 1 << order;
page_list_add_tail(page, &p2m->pod.super);
break;
case PAGE_ORDER_4K:
page_list_add_tail(page, &p2m->pod.single); /* lock: page_alloc */
p2m->pod.count += 1;
page_list_add_tail(page, &p2m->pod.single);
break;
default:
BUG();
}
p2m->pod.count += 1L << order;
return 0;
}
@@ -502,11 +505,10 @@ p2m_pod_decrease_reservation(struct domain *d,
unsigned int order)
{
int ret=0;
int i;
unsigned long i, n;
struct p2m_domain *p2m = p2m_get_hostp2m(d);
int steal_for_cache;
int pod, nonpod, ram;
bool_t steal_for_cache;
long pod, nonpod, ram;
gfn_lock(p2m, gpfn, order);
pod_lock(p2m);
@@ -525,21 +527,21 @@ recount:
/* Figure out if we need to steal some freed memory for our cache */
steal_for_cache = ( p2m->pod.entry_count > p2m->pod.count );
/* FIXME: Add contiguous; query for PSE entries? */
for ( i=0; i<(1<<order); i++)
for ( i = 0; i < (1UL << order); i += n )
{
p2m_access_t a;
p2m_type_t t;
unsigned int cur_order;
(void)p2m->get_entry(p2m, gpfn + i, &t, &a, 0, NULL, NULL);
p2m->get_entry(p2m, gpfn + i, &t, &a, 0, &cur_order, NULL);
n = 1UL << min(order, cur_order);
if ( t == p2m_populate_on_demand )
pod++;
pod += n;
else
{
nonpod++;
nonpod += n;
if ( p2m_is_ram(t) )
ram++;
ram += n;
}
}
@@ -574,41 +576,53 @@ recount:
* + There are PoD entries to handle, or
* + There is ram left, and we want to steal it
*/
for ( i=0;
i<(1<<order) && (pod>0 || (steal_for_cache && ram > 0));
i++)
for ( i = 0;
i < (1UL << order) && (pod > 0 || (steal_for_cache && ram > 0));
i += n )
{
mfn_t mfn;
p2m_type_t t;
p2m_access_t a;
unsigned int cur_order;
mfn = p2m->get_entry(p2m, gpfn + i, &t, &a, 0, NULL, NULL);
mfn = p2m->get_entry(p2m, gpfn + i, &t, &a, 0, &cur_order, NULL);
if ( order < cur_order )
cur_order = order;
n = 1UL << cur_order;
if ( t == p2m_populate_on_demand )
{
p2m_set_entry(p2m, gpfn + i, _mfn(INVALID_MFN), 0, p2m_invalid,
p2m->default_access);
p2m->pod.entry_count--;
p2m_set_entry(p2m, gpfn + i, _mfn(INVALID_MFN), cur_order,
p2m_invalid, p2m->default_access);
p2m->pod.entry_count -= n;
BUG_ON(p2m->pod.entry_count < 0);
pod--;
pod -= n;
}
else if ( steal_for_cache && p2m_is_ram(t) )
{
/*
* If we need less than 1 << cur_order, we may end up stealing
* more memory here than we actually need. This will be rectified
* below, however; and stealing too much and then freeing what we
* need may allow us to free smaller pages from the cache, and
* avoid breaking up superpages.
*/
struct page_info *page;
unsigned int j;
ASSERT(mfn_valid(mfn));
page = mfn_to_page(mfn);
p2m_set_entry(p2m, gpfn + i, _mfn(INVALID_MFN), 0, p2m_invalid,
p2m->default_access);
set_gpfn_from_mfn(mfn_x(mfn), INVALID_M2P_ENTRY);
p2m_pod_cache_add(p2m, page, 0);
p2m_set_entry(p2m, gpfn + i, _mfn(INVALID_MFN), cur_order,
p2m_invalid, p2m->default_access);
for ( j = 0; j < n; ++j )
set_gpfn_from_mfn(mfn_x(mfn), INVALID_M2P_ENTRY);
p2m_pod_cache_add(p2m, page, cur_order);
steal_for_cache = ( p2m->pod.entry_count > p2m->pod.count );
nonpod--;
ram--;
nonpod -= n;
ram -= n;
}
}
@@ -649,7 +663,8 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m, unsigned long gfn)
p2m_type_t type, type0 = 0;
unsigned long * map = NULL;
int ret=0, reset = 0;
int i, j;
unsigned long i, n;
unsigned int j;
int max_ref = 1;
struct domain *d = p2m->domain;
@@ -668,16 +683,14 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m, unsigned long gfn)
/* 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++ )
for ( i = 0; i < SUPERPAGE_PAGES; i += n )
{
p2m_access_t a;
mfn = p2m->get_entry(p2m, gfn + i, &type, &a, 0, NULL, NULL);
unsigned int cur_order;
unsigned long k;
const struct page_info *page;
if ( i == 0 )
{
mfn0 = mfn;
type0 = type;
}
mfn = p2m->get_entry(p2m, gfn + i, &type, &a, 0, &cur_order, NULL);
/* Conditions that must be met for superpage-superpage:
* + All gfns are ram types
@@ -690,15 +703,25 @@ p2m_pod_zero_check_superpage(struct p2m_domain *p2m, unsigned long gfn)
* + None of the mfns are likely to be mapped elsewhere (refcount
* 2 or less for shadow, 1 for hap)
*/
if ( !p2m_is_ram(type)
|| type != type0
|| ( (mfn_to_page(mfn)->count_info & PGC_allocated) == 0 )
|| ( (mfn_to_page(mfn)->count_info & (PGC_page_table|PGC_xen_heap)) != 0 )
|| ( (mfn_to_page(mfn)->count_info & PGC_xen_heap ) != 0 )
|| ( (mfn_to_page(mfn)->count_info & PGC_count_mask) > max_ref )
|| !( ( i == 0 && superpage_aligned(mfn_x(mfn0)) )
|| ( i != 0 && mfn_x(mfn) == (mfn_x(mfn0) + i) ) ) )
if ( !p2m_is_ram(type) )
goto out;
if ( i == 0 )
{
if ( !superpage_aligned(mfn_x(mfn)) )
goto out;
mfn0 = mfn;
type0 = type;
}
else if ( type != type0 || mfn_x(mfn) != (mfn_x(mfn0) + i) )
goto out;
n = 1UL << min(cur_order, SUPERPAGE_ORDER + 0U);
for ( k = 0, page = mfn_to_page(mfn); k < n; ++k, ++page )
if ( !(page->count_info & PGC_allocated) ||
(page->count_info & (PGC_page_table | PGC_xen_heap)) ||
(page->count_info & PGC_count_mask) > max_ref )
goto out;
}
/* Now, do a quick check to see if it may be zero before unmapping. */
@@ -1114,7 +1137,7 @@ guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long gfn,
unsigned int order)
{
struct p2m_domain *p2m = p2m_get_hostp2m(d);
unsigned long i, pod_count = 0;
unsigned long i, n, pod_count = 0;
p2m_type_t ot;
mfn_t omfn;
int rc = 0;
@@ -1127,10 +1150,13 @@ guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long gfn,
P2M_DEBUG("mark pod gfn=%#lx\n", gfn);
/* Make sure all gpfns are unused */
for ( i = 0; i < (1UL << order); i++ )
for ( i = 0; i < (1UL << order); i += n )
{
p2m_access_t a;
omfn = p2m->get_entry(p2m, gfn + i, &ot, &a, 0, NULL, NULL);
unsigned int cur_order;
omfn = p2m->get_entry(p2m, gfn + i, &ot, &a, 0, &cur_order, NULL);
n = 1UL << min(order, cur_order);
if ( p2m_is_ram(ot) )
{
P2M_DEBUG("gfn_to_mfn returned type %d!\n", ot);
@@ -1140,7 +1166,7 @@ guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long gfn,
else if ( ot == p2m_populate_on_demand )
{
/* Count how man PoD entries we'll be replacing if successful */
pod_count++;
pod_count += n;
}
}
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