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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v3 3/6] x86: extend mod_l*_entry() to optionally return the old PTE value
Calling mod_l*_entry() with a valid ol*e_out pointer will do an atomic
xchg to set the new pte value and return the old pte value through the
ol*e_out pointer. If the ol*e_out pointer is NULL then old behavior is
preserved.
Signed-off-by: Kevin Lampis <kevin.lampis@xxxxxxxxxx>
---
Changes in v3:
- Add swap to mod_l{2,3,4}_entry()
Changes in v2:
- UPDATE_ENTRY now returns the old pte value instead of using an out
pointer
---
xen/arch/x86/mm.c | 107 ++++++++++++++++++++++++++++++++++++----------
1 file changed, 85 insertions(+), 22 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 1ddb8b71469a..535a62139cad 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -2154,7 +2154,8 @@ static void l3t_unlock(struct page_info *page)
/* Update the L1 entry at pl1e to new value nl1e. */
static int mod_l1_entry(l1_pgentry_t *pl1e, l1_pgentry_t nl1e,
mfn_t gl1mfn, unsigned int update_flags,
- struct vcpu *pt_vcpu, struct domain *pg_dom)
+ struct vcpu *pt_vcpu, struct domain *pg_dom,
+ l1_pgentry_t *ol1e_out)
{
l1_pgentry_t ol1e = l1e_read(pl1e);
struct domain *pt_dom = pt_vcpu->domain;
@@ -2215,7 +2216,12 @@ static int mod_l1_entry(l1_pgentry_t *pl1e, l1_pgentry_t
nl1e,
/* Fast path for sufficiently-similar mappings. */
if ( !l1e_has_changed(ol1e, nl1e, ~FASTPATH_FLAG_WHITELIST) )
{
- UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, update_flags);
+ if ( ol1e_out )
+ *ol1e_out = UPDATE_ENTRY_SWAP(l1, pl1e, ol1e, nl1e, gl1mfn,
+ pt_vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu,
update_flags);
+
if ( page )
put_page(page);
return 0;
@@ -2238,14 +2244,25 @@ static int mod_l1_entry(l1_pgentry_t *pl1e,
l1_pgentry_t nl1e,
if ( page )
put_page(page);
- UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, update_flags);
+ if ( ol1e_out )
+ *ol1e_out = UPDATE_ENTRY_SWAP(l1, pl1e, ol1e, nl1e, gl1mfn,
+ pt_vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, update_flags);
}
else if ( pv_l1tf_check_l1e(pt_dom, nl1e) )
return -ERESTART;
else
- UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, update_flags);
+ {
+ if ( ol1e_out )
+ *ol1e_out = UPDATE_ENTRY_SWAP(l1, pl1e, ol1e, nl1e, gl1mfn,
+ pt_vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l1, pl1e, ol1e, nl1e, gl1mfn, pt_vcpu, update_flags);
+ }
put_page_from_l1e(ol1e, pt_dom);
+
return rc;
}
@@ -2255,7 +2272,8 @@ static int mod_l2_entry(l2_pgentry_t *pl2e,
l2_pgentry_t nl2e,
mfn_t mfn,
unsigned int update_flags,
- struct vcpu *vcpu)
+ struct vcpu *vcpu,
+ l2_pgentry_t *ol2e_out)
{
l2_pgentry_t ol2e;
struct domain *d = vcpu->domain;
@@ -2286,19 +2304,33 @@ static int mod_l2_entry(l2_pgentry_t *pl2e,
/* Fast path for sufficiently-similar mappings. */
if ( !l2e_has_changed(ol2e, nl2e, ~FASTPATH_PDE_FLAG_WHITELIST) )
{
- UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
+ if ( ol2e_out )
+ *ol2e_out = UPDATE_ENTRY_SWAP(l2, pl2e, ol2e, nl2e, mfn,
+ vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
return 0;
}
if ( unlikely((rc = get_page_from_l2e(nl2e, mfn, d, 0)) < 0) )
return rc;
- UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
+ if ( ol2e_out )
+ *ol2e_out = UPDATE_ENTRY_SWAP(l2, pl2e, ol2e, nl2e, mfn,
+ vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
}
else if ( pv_l1tf_check_l2e(d, nl2e) )
return -ERESTART;
else
- UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
+ {
+ if ( ol2e_out )
+ *ol2e_out = UPDATE_ENTRY_SWAP(l2, pl2e, ol2e, nl2e, mfn,
+ vcpu, update_flags);
+ else
+ UPDATE_ENTRY(l2, pl2e, ol2e, nl2e, mfn, vcpu, update_flags);
+ }
put_page_from_l2e(ol2e, mfn, PTF_defer);
@@ -2310,7 +2342,8 @@ static int mod_l3_entry(l3_pgentry_t *pl3e,
l3_pgentry_t nl3e,
mfn_t mfn,
unsigned int update_flags,
- struct vcpu *vcpu)
+ struct vcpu *vcpu,
+ l3_pgentry_t *ol3e_out)
{
l3_pgentry_t ol3e;
struct domain *d = vcpu->domain;
@@ -2339,7 +2372,11 @@ static int mod_l3_entry(l3_pgentry_t *pl3e,
/* Fast path for sufficiently-similar mappings. */
if ( !l3e_has_changed(ol3e, nl3e, ~FASTPATH_PDE_FLAG_WHITELIST) )
{
- UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
+ if ( ol3e_out )
+ *ol3e_out = UPDATE_ENTRY_SWAP(l3, pl3e, ol3e, nl3e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
return 0;
}
@@ -2348,12 +2385,22 @@ static int mod_l3_entry(l3_pgentry_t *pl3e,
return rc;
rc = 0;
- UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
+ if ( ol3e_out )
+ *ol3e_out = UPDATE_ENTRY_SWAP(l3, pl3e, ol3e, nl3e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
}
else if ( pv_l1tf_check_l3e(d, nl3e) )
return -ERESTART;
else
- UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
+ {
+ if ( ol3e_out )
+ *ol3e_out = UPDATE_ENTRY_SWAP(l3, pl3e, ol3e, nl3e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l3, pl3e, ol3e, nl3e, mfn, vcpu, update_flags);
+ }
put_page_from_l3e(ol3e, mfn, PTF_defer);
return rc;
@@ -2364,7 +2411,8 @@ static int mod_l4_entry(l4_pgentry_t *pl4e,
l4_pgentry_t nl4e,
mfn_t mfn,
unsigned int update_flags,
- struct vcpu *vcpu)
+ struct vcpu *vcpu,
+ l4_pgentry_t *ol4e_out)
{
struct domain *d = vcpu->domain;
l4_pgentry_t ol4e;
@@ -2393,7 +2441,11 @@ static int mod_l4_entry(l4_pgentry_t *pl4e,
/* Fast path for sufficiently-similar mappings. */
if ( !l4e_has_changed(ol4e, nl4e, ~FASTPATH_PDE_FLAG_WHITELIST) )
{
- UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
+ if ( ol4e_out )
+ *ol4e_out = UPDATE_ENTRY_SWAP(l4, pl4e, ol4e, nl4e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
return 0;
}
@@ -2402,12 +2454,22 @@ static int mod_l4_entry(l4_pgentry_t *pl4e,
return rc;
rc = 0;
- UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
+ if ( ol4e_out )
+ *ol4e_out = UPDATE_ENTRY_SWAP(l4, pl4e, ol4e, nl4e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
}
else if ( pv_l1tf_check_l4e(d, nl4e) )
return -ERESTART;
else
- UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
+ {
+ if ( ol4e_out )
+ *ol4e_out = UPDATE_ENTRY_SWAP(l4, pl4e, ol4e, nl4e, mfn, vcpu,
+ update_flags);
+ else
+ UPDATE_ENTRY(l4, pl4e, ol4e, nl4e, mfn, vcpu, update_flags);
+ }
put_page_from_l4e(ol4e, mfn, PTF_defer);
return rc;
@@ -3277,7 +3339,7 @@ int new_guest_cr3(mfn_t mfn)
l4e_from_mfn(mfn,
(_PAGE_PRESENT | _PAGE_RW |
_PAGE_USER | _PAGE_ACCESSED)),
- gt_mfn, 0, curr);
+ gt_mfn, 0, curr, NULL);
unmap_domain_page(pl4e);
switch ( rc )
{
@@ -4115,14 +4177,14 @@ long do_mmu_update(
{
case PGT_l1_page_table:
rc = mod_l1_entry(va, l1e_from_intpte(req.val), mfn,
- update_flags, v, pg_owner);
+ update_flags, v, pg_owner, NULL);
break;
case PGT_l2_page_table:
if ( unlikely(pg_owner != pt_owner) )
break;
rc = mod_l2_entry(va, l2e_from_intpte(req.val), mfn,
- update_flags, v);
+ update_flags, v, NULL);
if ( !rc )
flush_linear_pt = true;
break;
@@ -4131,7 +4193,7 @@ long do_mmu_update(
if ( unlikely(pg_owner != pt_owner) )
break;
rc = mod_l3_entry(va, l3e_from_intpte(req.val), mfn,
- update_flags, v);
+ update_flags, v, NULL);
if ( !rc )
flush_linear_pt = true;
break;
@@ -4140,7 +4202,7 @@ long do_mmu_update(
if ( unlikely(pg_owner != pt_owner) )
break;
rc = mod_l4_entry(va, l4e_from_intpte(req.val), mfn,
- update_flags, v);
+ update_flags, v, NULL);
if ( !rc )
flush_linear_pt = true;
if ( !rc && pt_owner->arch.pv.xpti )
@@ -4480,7 +4542,8 @@ static int __do_update_va_mapping(
goto out;
}
- rc = mod_l1_entry(pl1e, val, gl1mfn, MMU_NORMAL_PT_UPDATE, v, pg_owner);
+ rc = mod_l1_entry(pl1e, val, gl1mfn, MMU_NORMAL_PT_UPDATE, v, pg_owner,
+ NULL);
page_unlock(gl1pg);
put_page(gl1pg);
--
2.52.0
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