From: Hongyan Xia <hongyxia@amazon.com>
To: <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wl@xen.org>, "Jan Beulich" <jbeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH v4 4/9] x86/mm: introduce l{1, 2}t local variables to modify_xen_mappings
Date: Wed, 4 Dec 2019 17:10:56 +0000 [thread overview]
Message-ID: <b23924c9bdfe076c970dad4cbd9fa4d946d0a168.1575477921.git.hongyxia@amazon.com> (raw)
In-Reply-To: <cover.1575477921.git.hongyxia@amazon.com>
From: Wei Liu <wei.liu2@citrix.com>
The pl2e and pl1e variables are heavily (ab)used in that function. It
is fine at the moment because all page tables are always mapped so
there is no need to track the life time of each variable.
We will soon have the requirement to map and unmap page tables. We
need to track the life time of each variable to avoid leakage.
Introduce some l{1,2}t variables with limited scope so that we can
track life time of pointers to xen page tables more easily.
No functional change.
Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
---
xen/arch/x86/mm.c | 68 ++++++++++++++++++++++++++---------------------
1 file changed, 38 insertions(+), 30 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 790578d2b3..303bc35549 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5601,6 +5601,8 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
if ( l3e_get_flags(*pl3e) & _PAGE_PSE )
{
+ l2_pgentry_t *l2t;
+
if ( l2_table_offset(v) == 0 &&
l1_table_offset(v) == 0 &&
((e - v) >= (1UL << L3_PAGETABLE_SHIFT)) )
@@ -5616,11 +5618,11 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
}
/* PAGE1GB: shatter the superpage and fall through. */
- pl2e = alloc_xen_pagetable();
- if ( !pl2e )
+ l2t = alloc_xen_pagetable();
+ if ( !l2t )
return -ENOMEM;
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- l2e_write(pl2e + i,
+ l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(*pl3e) +
(i << PAGETABLE_ORDER),
l3e_get_flags(*pl3e)));
@@ -5629,14 +5631,14 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
if ( (l3e_get_flags(*pl3e) & _PAGE_PRESENT) &&
(l3e_get_flags(*pl3e) & _PAGE_PSE) )
{
- l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(pl2e),
+ l3e_write_atomic(pl3e, l3e_from_mfn(virt_to_mfn(l2t),
__PAGE_HYPERVISOR));
- pl2e = NULL;
+ l2t = NULL;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
- if ( pl2e )
- free_xen_pagetable(pl2e);
+ if ( l2t )
+ free_xen_pagetable(l2t);
}
/*
@@ -5670,12 +5672,14 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
}
else
{
+ l1_pgentry_t *l1t;
+
/* PSE: shatter the superpage and try again. */
- pl1e = alloc_xen_pagetable();
- if ( !pl1e )
+ l1t = alloc_xen_pagetable();
+ if ( !l1t )
return -ENOMEM;
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- l1e_write(&pl1e[i],
+ l1e_write(&l1t[i],
l1e_from_pfn(l2e_get_pfn(*pl2e) + i,
l2e_get_flags(*pl2e) & ~_PAGE_PSE));
if ( locking )
@@ -5683,19 +5687,19 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
if ( (l2e_get_flags(*pl2e) & _PAGE_PRESENT) &&
(l2e_get_flags(*pl2e) & _PAGE_PSE) )
{
- l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(pl1e),
+ l2e_write_atomic(pl2e, l2e_from_mfn(virt_to_mfn(l1t),
__PAGE_HYPERVISOR));
- pl1e = NULL;
+ l1t = NULL;
}
if ( locking )
spin_unlock(&map_pgdir_lock);
- if ( pl1e )
- free_xen_pagetable(pl1e);
+ if ( l1t )
+ free_xen_pagetable(l1t);
}
}
else
{
- l1_pgentry_t nl1e;
+ l1_pgentry_t nl1e, *l1t;
/*
* Ordinary 4kB mapping: The L2 entry has been verified to be
@@ -5742,9 +5746,9 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
continue;
}
- pl1e = l2e_to_l1e(*pl2e);
+ l1t = l2e_to_l1e(*pl2e);
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- if ( l1e_get_intpte(pl1e[i]) != 0 )
+ if ( l1e_get_intpte(l1t[i]) != 0 )
break;
if ( i == L1_PAGETABLE_ENTRIES )
{
@@ -5753,7 +5757,7 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
if ( locking )
spin_unlock(&map_pgdir_lock);
flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
- free_xen_pagetable(pl1e);
+ free_xen_pagetable(l1t);
}
else if ( locking )
spin_unlock(&map_pgdir_lock);
@@ -5782,21 +5786,25 @@ int modify_xen_mappings(unsigned long s, unsigned long e, unsigned int nf)
continue;
}
- pl2e = l3e_to_l2e(*pl3e);
- for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- if ( l2e_get_intpte(pl2e[i]) != 0 )
- break;
- if ( i == L2_PAGETABLE_ENTRIES )
{
- /* Empty: zap the L3E and free the L2 page. */
- l3e_write_atomic(pl3e, l3e_empty());
- if ( locking )
+ l2_pgentry_t *l2t;
+
+ l2t = l3e_to_l2e(*pl3e);
+ for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
+ if ( l2e_get_intpte(l2t[i]) != 0 )
+ break;
+ if ( i == L2_PAGETABLE_ENTRIES )
+ {
+ /* Empty: zap the L3E and free the L2 page. */
+ l3e_write_atomic(pl3e, l3e_empty());
+ if ( locking )
+ spin_unlock(&map_pgdir_lock);
+ flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
+ free_xen_pagetable(l2t);
+ }
+ else if ( locking )
spin_unlock(&map_pgdir_lock);
- flush_area(NULL, FLUSH_TLB_GLOBAL); /* flush before free */
- free_xen_pagetable(pl2e);
}
- else if ( locking )
- spin_unlock(&map_pgdir_lock);
}
flush_area(NULL, FLUSH_TLB_GLOBAL);
--
2.17.1
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next prev parent reply other threads:[~2019-12-04 17:11 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-04 17:10 [Xen-devel] [PATCH v4 0/9] Add alternative API for Xen PTEs Hongyan Xia
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 1/9] x86: move some xen mm function declarations Hongyan Xia
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 2/9] x86: introduce a new set of APIs to manage Xen page tables Hongyan Xia
2019-12-04 17:54 ` Xia, Hongyan
2019-12-05 7:20 ` Jan Beulich
2019-12-11 16:33 ` Julien Grall
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 3/9] x86/mm: introduce l{1, 2}t local variables to map_pages_to_xen Hongyan Xia
2019-12-04 18:01 ` Xia, Hongyan
2019-12-05 8:38 ` Jan Beulich
2019-12-04 17:10 ` Hongyan Xia [this message]
2019-12-12 14:34 ` [Xen-devel] [PATCH v4 4/9] x86/mm: introduce l{1, 2}t local variables to modify_xen_mappings Julien Grall
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 5/9] x86/mm: map_pages_to_xen would better have one exit path Hongyan Xia
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 6/9] x86/mm: add an end_of_loop label in map_pages_to_xen Hongyan Xia
2019-12-05 10:21 ` Xia, Hongyan
2019-12-05 10:25 ` Jan Beulich
2019-12-05 11:02 ` Durrant, Paul
2019-12-05 11:12 ` Jan Beulich
2019-12-05 13:22 ` Xia, Hongyan
2019-12-06 15:58 ` Xia, Hongyan
2019-12-04 17:10 ` [Xen-devel] [PATCH v4 7/9] x86/mm: make sure there is one exit path for modify_xen_mappings Hongyan Xia
2019-12-04 17:11 ` [Xen-devel] [PATCH v4 8/9] x86/mm: add an end_of_loop label in modify_xen_mappings Hongyan Xia
2019-12-04 17:11 ` [Xen-devel] [PATCH v4 9/9] x86/mm: change pl*e to l*t in virt_to_xen_l*e Hongyan Xia
2019-12-05 9:14 ` [Xen-devel] [PATCH v4 0/9] Add alternative API for Xen PTEs Jan Beulich
2019-12-05 9:41 ` Xia, Hongyan
2019-12-05 9:51 ` Jan Beulich
2019-12-05 10:45 ` Xia, Hongyan
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