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[xen-unstable] grant-tables: Use get_page_from_gfn() instead of get_gfn()/put_gfn.

 

 

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patchbot at xen

May 18, 2012, 10:11 AM

Post #1 of 1 (48 views)
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[xen-unstable] grant-tables: Use get_page_from_gfn() instead of get_gfn()/put_gfn.

# HG changeset patch
# User Andres Lagar-Cavilla <andres [at] lagarcavilla>
# Date 1337246694 -3600
# Node ID 1e5cf32b7b7114e88507085ff7a88fc89b9a2c15
# Parent de050e895ea27e456258cf70418943e05378b37e
grant-tables: Use get_page_from_gfn() instead of get_gfn()/put_gfn.

This requires some careful re-engineering of __get_paged_frame and its callers.
Functions that previously returned gfn's to be put now return pages to be put.

Tested with Win7 + Citrix PV drivers guest, using speedtest for networking
(yes!) plus the loginVSI framework to constantly hit disk.

Signed-off-by: Andres Lagar-Cavilla <andres [at] lagarcavilla>
---


diff -r de050e895ea2 -r 1e5cf32b7b71 xen/common/grant_table.c
--- a/xen/common/grant_table.c Thu May 17 10:24:54 2012 +0100
+++ b/xen/common/grant_table.c Thu May 17 10:24:54 2012 +0100
@@ -107,18 +107,6 @@ static unsigned inline int max_nr_maptra
return (max_nr_grant_frames * MAX_MAPTRACK_TO_GRANTS_RATIO);
}

-#ifdef CONFIG_X86
-#define gfn_to_mfn_private(_d, _gfn) ({ \
- p2m_type_t __p2mt; \
- unsigned long __x; \
- __x = mfn_x(get_gfn_unshare((_d), (_gfn), &__p2mt)); \
- if ( p2m_is_shared(__p2mt) || !p2m_is_valid(__p2mt) ) \
- __x = INVALID_MFN; \
- __x; })
-#else
-#define gfn_to_mfn_private(_d, _gfn) gmfn_to_mfn(_d, _gfn)
-#endif
-
#define SHGNT_PER_PAGE_V1 (PAGE_SIZE / sizeof(grant_entry_v1_t))
#define shared_entry_v1(t, e) \
((t)->shared_v1[(e)/SHGNT_PER_PAGE_V1][(e)%SHGNT_PER_PAGE_V1])
@@ -141,41 +129,41 @@ shared_entry_header(struct grant_table *
#define active_entry(t, e) \
((t)->active[(e)/ACGNT_PER_PAGE][(e)%ACGNT_PER_PAGE])

-/* Check if the page has been paged out. If rc == GNTST_okay, caller must do put_gfn(rd, gfn) */
-static int __get_paged_frame(unsigned long gfn, unsigned long *frame, int readonly, struct domain *rd)
+/* Check if the page has been paged out, or needs unsharing.
+ If rc == GNTST_okay, *page contains the page struct with a ref taken.
+ Caller must do put_page(*page).
+ If any error, *page = NULL, *frame = INVALID_MFN, no ref taken. */
+static int __get_paged_frame(unsigned long gfn, unsigned long *frame, struct page_info **page,
+ int readonly, struct domain *rd)
{
int rc = GNTST_okay;
#if defined(P2M_PAGED_TYPES) || defined(P2M_SHARED_TYPES)
p2m_type_t p2mt;
- mfn_t mfn;
-
- if ( readonly )
- mfn = get_gfn(rd, gfn, &p2mt);
- else
+
+ *page = get_page_from_gfn(rd, gfn, &p2mt,
+ (readonly) ? P2M_ALLOC : P2M_UNSHARE);
+ if ( !(*page) )
{
- mfn = get_gfn_unshare(rd, gfn, &p2mt);
+ *frame = INVALID_MFN;
if ( p2m_is_shared(p2mt) )
+ return GNTST_eagain;
+ if ( p2m_is_paging(p2mt) )
{
- put_gfn(rd, gfn);
+ p2m_mem_paging_populate(rd, gfn);
return GNTST_eagain;
}
+ return GNTST_bad_page;
}
-
- if ( p2m_is_valid(p2mt) ) {
- *frame = mfn_x(mfn);
- if ( p2m_is_paging(p2mt) )
- {
- put_gfn(rd, gfn);
- p2m_mem_paging_populate(rd, gfn);
- rc = GNTST_eagain;
- }
- } else {
- put_gfn(rd, gfn);
- *frame = INVALID_MFN;
- rc = GNTST_bad_page;
+ *frame = page_to_mfn(*page);
+#else
+ *frame = gmfn_to_mfn(rd, gfn);
+ *page = mfn_valid(*frame) ? mfn_to_page(*frame) : NULL;
+ if ( (!(*page)) || (!get_page(*page, rd)) )
+ {
+ *frame = INVALID_MFN;
+ *page = NULL;
+ rc = GNTST_bad_page;
}
-#else
- *frame = readonly ? gmfn_to_mfn(rd, gfn) : gfn_to_mfn_private(rd, gfn);
#endif

return rc;
@@ -470,12 +458,11 @@ static void
__gnttab_map_grant_ref(
struct gnttab_map_grant_ref *op)
{
- struct domain *ld, *rd, *owner;
+ struct domain *ld, *rd, *owner = NULL;
struct vcpu *led;
int handle;
- unsigned long gfn = INVALID_GFN;
unsigned long frame = 0, nr_gets = 0;
- struct page_info *pg;
+ struct page_info *pg = NULL;
int rc = GNTST_okay;
u32 old_pin;
u32 act_pin;
@@ -573,13 +560,11 @@ __gnttab_map_grant_ref(
{
unsigned long frame;

- gfn = sha1 ? sha1->frame : sha2->full_page.frame;
- rc = __get_paged_frame(gfn, &frame, !!(op->flags & GNTMAP_readonly), rd);
+ unsigned long gfn = sha1 ? sha1->frame : sha2->full_page.frame;
+ rc = __get_paged_frame(gfn, &frame, &pg,
+ !!(op->flags & GNTMAP_readonly), rd);
if ( rc != GNTST_okay )
- {
- gfn = INVALID_GFN;
goto unlock_out_clear;
- }
act->gfn = gfn;
act->domid = ld->domain_id;
act->frame = frame;
@@ -606,9 +591,17 @@ __gnttab_map_grant_ref(

spin_unlock(&rd->grant_table->lock);

- pg = mfn_valid(frame) ? mfn_to_page(frame) : NULL;
-
- if ( !pg || (owner = page_get_owner_and_reference(pg)) == dom_io )
+ /* pg may be set, with a refcount included, from __get_paged_frame */
+ if ( !pg )
+ {
+ pg = mfn_valid(frame) ? mfn_to_page(frame) : NULL;
+ if ( pg )
+ owner = page_get_owner_and_reference(pg);
+ }
+ else
+ owner = page_get_owner(pg);
+
+ if ( !pg || (owner == dom_io) )
{
/* Only needed the reference to confirm dom_io ownership. */
if ( pg )
@@ -708,8 +701,6 @@ __gnttab_map_grant_ref(
op->handle = handle;
op->status = GNTST_okay;

- if ( gfn != INVALID_GFN )
- put_gfn(rd, gfn);
rcu_unlock_domain(rd);
return;

@@ -748,8 +739,6 @@ __gnttab_map_grant_ref(
gnttab_clear_flag(_GTF_reading, status);

unlock_out:
- if ( gfn != INVALID_GFN )
- put_gfn(rd, gfn);
spin_unlock(&rd->grant_table->lock);
op->status = rc;
put_maptrack_handle(ld->grant_table, handle);
@@ -1479,7 +1468,16 @@ gnttab_transfer(
return -EFAULT;
}

- mfn = gfn_to_mfn_private(d, gop.mfn);
+#ifdef CONFIG_X86
+ {
+ p2m_type_t __p2mt;
+ mfn = mfn_x(get_gfn_unshare(d, gop.mfn, &__p2mt));
+ if ( p2m_is_shared(__p2mt) || !p2m_is_valid(__p2mt) )
+ mfn = INVALID_MFN;
+ }
+#else
+ mfn = gmfn_to_mfn(d, gop.mfn);
+#endif

/* Check the passed page frame for basic validity. */
if ( unlikely(!mfn_valid(mfn)) )
@@ -1723,15 +1721,14 @@ static void __fixup_status_for_pin(const
}

/* Grab a frame number from a grant entry and update the flags and pin
- count as appropriate. Note that this does *not* update the page
- type or reference counts, and does not check that the mfn is
- actually valid. If *gfn != INVALID_GFN, and rc == GNTST_okay, then
- we leave this function holding the p2m entry for *gfn in *owning_domain */
+ count as appropriate. If rc == GNTST_okay, note that this *does*
+ take one ref count on the target page, stored in *page.
+ If there is any error, *page = NULL, no ref taken. */
static int
__acquire_grant_for_copy(
struct domain *rd, unsigned long gref, struct domain *ld, int readonly,
- unsigned long *frame, unsigned long *gfn, unsigned *page_off, unsigned *length,
- unsigned allow_transitive, struct domain **owning_domain)
+ unsigned long *frame, struct page_info **page,
+ unsigned *page_off, unsigned *length, unsigned allow_transitive)
{
grant_entry_v1_t *sha1;
grant_entry_v2_t *sha2;
@@ -1746,11 +1743,9 @@ __acquire_grant_for_copy(
unsigned trans_page_off;
unsigned trans_length;
int is_sub_page;
- struct domain *ignore;
s16 rc = GNTST_okay;

- *owning_domain = NULL;
- *gfn = INVALID_GFN;
+ *page = NULL;

spin_lock(&rd->grant_table->lock);

@@ -1827,14 +1822,13 @@ __acquire_grant_for_copy(
spin_unlock(&rd->grant_table->lock);

rc = __acquire_grant_for_copy(td, trans_gref, rd,
- readonly, &grant_frame, gfn,
- &trans_page_off, &trans_length,
- 0, &ignore);
+ readonly, &grant_frame, page,
+ &trans_page_off, &trans_length, 0);

spin_lock(&rd->grant_table->lock);
if ( rc != GNTST_okay ) {
__fixup_status_for_pin(act, status);
- rcu_unlock_domain(td);
+ rcu_unlock_domain(td);
spin_unlock(&rd->grant_table->lock);
return rc;
}
@@ -1846,56 +1840,49 @@ __acquire_grant_for_copy(
if ( act->pin != old_pin )
{
__fixup_status_for_pin(act, status);
- rcu_unlock_domain(td);
+ rcu_unlock_domain(td);
spin_unlock(&rd->grant_table->lock);
+ put_page(*page);
return __acquire_grant_for_copy(rd, gref, ld, readonly,
- frame, gfn, page_off, length,
- allow_transitive,
- owning_domain);
+ frame, page, page_off, length,
+ allow_transitive);
}

/* The actual remote remote grant may or may not be a
sub-page, but we always treat it as one because that
blocks mappings of transitive grants. */
is_sub_page = 1;
- *owning_domain = td;
act->gfn = -1ul;
}
else if ( sha1 )
{
- *gfn = sha1->frame;
- rc = __get_paged_frame(*gfn, &grant_frame, readonly, rd);
+ rc = __get_paged_frame(sha1->frame, &grant_frame, page, readonly, rd);
if ( rc != GNTST_okay )
goto unlock_out;
- act->gfn = *gfn;
+ act->gfn = sha1->frame;
is_sub_page = 0;
trans_page_off = 0;
trans_length = PAGE_SIZE;
- *owning_domain = rd;
}
else if ( !(sha2->hdr.flags & GTF_sub_page) )
{
- *gfn = sha2->full_page.frame;
- rc = __get_paged_frame(*gfn, &grant_frame, readonly, rd);
+ rc = __get_paged_frame(sha2->full_page.frame, &grant_frame, page, readonly, rd);
if ( rc != GNTST_okay )
goto unlock_out;
- act->gfn = *gfn;
+ act->gfn = sha2->full_page.frame;
is_sub_page = 0;
trans_page_off = 0;
trans_length = PAGE_SIZE;
- *owning_domain = rd;
}
else
{
- *gfn = sha2->sub_page.frame;
- rc = __get_paged_frame(*gfn, &grant_frame, readonly, rd);
+ rc = __get_paged_frame(sha2->sub_page.frame, &grant_frame, page, readonly, rd);
if ( rc != GNTST_okay )
goto unlock_out;
- act->gfn = *gfn;
+ act->gfn = sha2->sub_page.frame;
is_sub_page = 1;
trans_page_off = sha2->sub_page.page_off;
trans_length = sha2->sub_page.length;
- *owning_domain = rd;
}

if ( !act->pin )
@@ -1911,7 +1898,9 @@ __acquire_grant_for_copy(
}
else
{
- *owning_domain = rd;
+ ASSERT(mfn_valid(act->frame));
+ *page = mfn_to_page(act->frame);
+ (void)page_get_owner_and_reference(*page);
}

act->pin += readonly ? GNTPIN_hstr_inc : GNTPIN_hstw_inc;
@@ -1930,11 +1919,11 @@ __gnttab_copy(
struct gnttab_copy *op)
{
struct domain *sd = NULL, *dd = NULL;
- struct domain *source_domain = NULL, *dest_domain = NULL;
- unsigned long s_frame, d_frame, s_gfn = INVALID_GFN, d_gfn = INVALID_GFN;
+ unsigned long s_frame, d_frame;
+ struct page_info *s_pg = NULL, *d_pg = NULL;
char *sp, *dp;
s16 rc = GNTST_okay;
- int have_d_grant = 0, have_s_grant = 0, have_s_ref = 0;
+ int have_d_grant = 0, have_s_grant = 0;
int src_is_gref, dest_is_gref;

if ( ((op->source.offset + op->len) > PAGE_SIZE) ||
@@ -1972,82 +1961,54 @@ __gnttab_copy(
{
unsigned source_off, source_len;
rc = __acquire_grant_for_copy(sd, op->source.u.ref, current->domain, 1,
- &s_frame, &s_gfn, &source_off, &source_len, 1,
- &source_domain);
+ &s_frame, &s_pg, &source_off, &source_len, 1);
if ( rc != GNTST_okay )
goto error_out;
have_s_grant = 1;
if ( op->source.offset < source_off ||
op->len > source_len )
- PIN_FAIL(error_put_s_gfn, GNTST_general_error,
+ PIN_FAIL(error_out, GNTST_general_error,
"copy source out of bounds: %d < %d || %d > %d\n",
op->source.offset, source_off,
op->len, source_len);
}
else
{
-#ifdef CONFIG_X86
- s_gfn = op->source.u.gmfn;
- rc = __get_paged_frame(op->source.u.gmfn, &s_frame, 1, sd);
+ rc = __get_paged_frame(op->source.u.gmfn, &s_frame, &s_pg, 1, sd);
if ( rc != GNTST_okay )
- goto error_out;
-#else
- s_frame = gmfn_to_mfn(sd, op->source.u.gmfn);
-#endif
- source_domain = sd;
+ PIN_FAIL(error_out, rc,
+ "source frame %lx invalid.\n", s_frame);
}
- if ( unlikely(!mfn_valid(s_frame)) )
- PIN_FAIL(error_put_s_gfn, GNTST_general_error,
- "source frame %lx invalid.\n", s_frame);
- /* For the source frame, the page could still be shared, so
- * don't assume ownership by source_domain */
- if ( !page_get_owner_and_reference(mfn_to_page(s_frame)) )
- {
- if ( !sd->is_dying )
- gdprintk(XENLOG_WARNING, "Could not get src frame %lx\n", s_frame);
- rc = GNTST_general_error;
- goto error_put_s_gfn;
- }
- have_s_ref = 1;

if ( dest_is_gref )
{
unsigned dest_off, dest_len;
rc = __acquire_grant_for_copy(dd, op->dest.u.ref, current->domain, 0,
- &d_frame, &d_gfn, &dest_off, &dest_len, 1,
- &dest_domain);
+ &d_frame, &d_pg, &dest_off, &dest_len, 1);
if ( rc != GNTST_okay )
- goto error_put_s_gfn;
+ goto error_out;
have_d_grant = 1;
if ( op->dest.offset < dest_off ||
op->len > dest_len )
- PIN_FAIL(error_put_d_gfn, GNTST_general_error,
+ PIN_FAIL(error_out, GNTST_general_error,
"copy dest out of bounds: %d < %d || %d > %d\n",
op->dest.offset, dest_off,
op->len, dest_len);
}
else
{
-#ifdef CONFIG_X86
- d_gfn = op->dest.u.gmfn;
- rc = __get_paged_frame(op->dest.u.gmfn, &d_frame, 0, dd);
+ rc = __get_paged_frame(op->dest.u.gmfn, &d_frame, &d_pg, 0, dd);
if ( rc != GNTST_okay )
- goto error_put_s_gfn;
-#else
- d_frame = gmfn_to_mfn(dd, op->dest.u.gmfn);
-#endif
- dest_domain = dd;
+ PIN_FAIL(error_out, rc,
+ "destination frame %lx invalid.\n", d_frame);
}
- if ( unlikely(!mfn_valid(d_frame)) )
- PIN_FAIL(error_put_d_gfn, GNTST_general_error,
- "destination frame %lx invalid.\n", d_frame);
- if ( !get_page_and_type(mfn_to_page(d_frame), dest_domain,
- PGT_writable_page) )
+
+ if ( !get_page_type(d_pg, PGT_writable_page) )
{
if ( !dd->is_dying )
gdprintk(XENLOG_WARNING, "Could not get dst frame %lx\n", d_frame);
rc = GNTST_general_error;
- goto error_put_d_gfn;
+ goto error_out;
}

sp = map_domain_page(s_frame);
@@ -2060,16 +2021,12 @@ __gnttab_copy(

gnttab_mark_dirty(dd, d_frame);

- put_page_and_type(mfn_to_page(d_frame));
- error_put_d_gfn:
- if ( (d_gfn != INVALID_GFN) && (dest_domain) )
- put_gfn(dest_domain, d_gfn);
- error_put_s_gfn:
- if ( (s_gfn != INVALID_GFN) && (source_domain) )
- put_gfn(source_domain, s_gfn);
+ put_page_type(d_pg);
error_out:
- if ( have_s_ref )
- put_page(mfn_to_page(s_frame));
+ if ( d_pg )
+ put_page(d_pg);
+ if ( s_pg )
+ put_page(s_pg);
if ( have_s_grant )
__release_grant_for_copy(sd, op->source.u.ref, 1);
if ( have_d_grant )

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