From: Hongyan Xia <hongyxia@amazon.com>
To: <xen-devel@lists.xenproject.org>
Cc: "Wei Liu" <wei.liu2@citrix.com>, "Wei Liu" <wl@xen.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
jgrall@amazon.com, "Jan Beulich" <jbeulich@suse.com>,
"Roger Pau Monné" <roger.pau@citrix.com>
Subject: [Xen-devel] [PATCH v5 3/7] x86/mm: introduce l{1, 2}t local variables to map_pages_to_xen
Date: Tue, 7 Jan 2020 12:06:45 +0000 [thread overview]
Message-ID: <be3cd4478ca238809c40a8f3e2c8cc1ef247e57b.1578397252.git.hongyxia@amazon.com> (raw)
In-Reply-To: <cover.1578397252.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>
---
Changed since v4:
- style fixes.
- const qualify introduced variables.
---
xen/arch/x86/mm.c | 72 ++++++++++++++++++++++++++++++-------------------------
1 file changed, 39 insertions(+), 33 deletions(-)
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 22b55390f1..699aa6bbdf 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -5211,10 +5211,11 @@ int map_pages_to_xen(
}
else
{
- pl2e = l3e_to_l2e(ol3e);
+ l2_pgentry_t *l2t = l3e_to_l2e(ol3e);
+
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
{
- ol2e = pl2e[i];
+ ol2e = l2t[i];
if ( !(l2e_get_flags(ol2e) & _PAGE_PRESENT) )
continue;
if ( l2e_get_flags(ol2e) & _PAGE_PSE )
@@ -5222,21 +5223,21 @@ int map_pages_to_xen(
else
{
unsigned int j;
+ const l1_pgentry_t *l1t = l2e_to_l1e(ol2e);
- pl1e = l2e_to_l1e(ol2e);
for ( j = 0; j < L1_PAGETABLE_ENTRIES; j++ )
- flush_flags(l1e_get_flags(pl1e[j]));
+ flush_flags(l1e_get_flags(l1t[j]));
}
}
flush_area(virt, flush_flags);
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
{
- ol2e = pl2e[i];
+ ol2e = l2t[i];
if ( (l2e_get_flags(ol2e) & _PAGE_PRESENT) &&
!(l2e_get_flags(ol2e) & _PAGE_PSE) )
free_xen_pagetable(l2e_to_l1e(ol2e));
}
- free_xen_pagetable(pl2e);
+ free_xen_pagetable(l2t);
}
}
@@ -5252,6 +5253,7 @@ int map_pages_to_xen(
{
unsigned int flush_flags =
FLUSH_TLB | FLUSH_ORDER(2 * PAGETABLE_ORDER);
+ l2_pgentry_t *l2t;
/* Skip this PTE if there is no change. */
if ( ((l3e_get_pfn(ol3e) & ~(L2_PAGETABLE_ENTRIES *
@@ -5273,12 +5275,12 @@ int map_pages_to_xen(
continue;
}
- pl2e = alloc_xen_pagetable();
- if ( pl2e == NULL )
+ l2t = alloc_xen_pagetable();
+ if ( l2t == NULL )
return -ENOMEM;
for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
- l2e_write(pl2e + i,
+ l2e_write(l2t + i,
l2e_from_pfn(l3e_get_pfn(ol3e) +
(i << PAGETABLE_ORDER),
l3e_get_flags(ol3e)));
@@ -5291,15 +5293,15 @@ int map_pages_to_xen(
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);
flush_area(virt, flush_flags);
- if ( pl2e )
- free_xen_pagetable(pl2e);
+ if ( l2t )
+ free_xen_pagetable(l2t);
}
pl2e = virt_to_xen_l2e(virt);
@@ -5327,11 +5329,12 @@ int map_pages_to_xen(
}
else
{
- pl1e = l2e_to_l1e(ol2e);
+ l1_pgentry_t *l1t = l2e_to_l1e(ol2e);
+
for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
- flush_flags(l1e_get_flags(pl1e[i]));
+ flush_flags(l1e_get_flags(l1t[i]));
flush_area(virt, flush_flags);
- free_xen_pagetable(pl1e);
+ free_xen_pagetable(l1t);
}
}
@@ -5353,6 +5356,7 @@ int map_pages_to_xen(
{
unsigned int flush_flags =
FLUSH_TLB | FLUSH_ORDER(PAGETABLE_ORDER);
+ l1_pgentry_t *l1t;
/* Skip this PTE if there is no change. */
if ( (((l2e_get_pfn(*pl2e) & ~(L1_PAGETABLE_ENTRIES - 1)) +
@@ -5372,12 +5376,12 @@ int map_pages_to_xen(
goto check_l3;
}
- pl1e = alloc_xen_pagetable();
- if ( pl1e == NULL )
+ l1t = alloc_xen_pagetable();
+ if ( l1t == NULL )
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,
lNf_to_l1f(l2e_get_flags(*pl2e))));
@@ -5389,15 +5393,15 @@ int map_pages_to_xen(
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);
flush_area(virt, flush_flags);
- if ( pl1e )
- free_xen_pagetable(pl1e);
+ if ( l1t )
+ free_xen_pagetable(l1t);
}
pl1e = l2e_to_l1e(*pl2e) + l1_table_offset(virt);
@@ -5422,6 +5426,7 @@ int map_pages_to_xen(
((1u << PAGETABLE_ORDER) - 1)) == 0)) )
{
unsigned long base_mfn;
+ const l1_pgentry_t *l1t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5445,11 +5450,11 @@ int map_pages_to_xen(
goto check_l3;
}
- pl1e = l2e_to_l1e(ol2e);
- base_mfn = l1e_get_pfn(*pl1e) & ~(L1_PAGETABLE_ENTRIES - 1);
- for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++, pl1e++ )
- if ( (l1e_get_pfn(*pl1e) != (base_mfn + i)) ||
- (l1e_get_flags(*pl1e) != flags) )
+ l1t = l2e_to_l1e(ol2e);
+ base_mfn = l1e_get_pfn(l1t[0]) & ~(L1_PAGETABLE_ENTRIES - 1);
+ for ( i = 0; i < L1_PAGETABLE_ENTRIES; i++ )
+ if ( (l1e_get_pfn(l1t[i]) != (base_mfn + i)) ||
+ (l1e_get_flags(l1t[i]) != flags) )
break;
if ( i == L1_PAGETABLE_ENTRIES )
{
@@ -5475,6 +5480,7 @@ int map_pages_to_xen(
((1UL << (L3_PAGETABLE_SHIFT - PAGE_SHIFT)) - 1))) )
{
unsigned long base_mfn;
+ const l2_pgentry_t *l2t;
if ( locking )
spin_lock(&map_pgdir_lock);
@@ -5492,13 +5498,13 @@ int map_pages_to_xen(
continue;
}
- pl2e = l3e_to_l2e(ol3e);
- base_mfn = l2e_get_pfn(*pl2e) & ~(L2_PAGETABLE_ENTRIES *
+ l2t = l3e_to_l2e(ol3e);
+ base_mfn = l2e_get_pfn(l2t[0]) & ~(L2_PAGETABLE_ENTRIES *
L1_PAGETABLE_ENTRIES - 1);
- for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++, pl2e++ )
- if ( (l2e_get_pfn(*pl2e) !=
+ for ( i = 0; i < L2_PAGETABLE_ENTRIES; i++ )
+ if ( (l2e_get_pfn(l2t[i]) !=
(base_mfn + (i << PAGETABLE_ORDER))) ||
- (l2e_get_flags(*pl2e) != l1f_to_lNf(flags)) )
+ (l2e_get_flags(l2t[i]) != l1f_to_lNf(flags)) )
break;
if ( i == L2_PAGETABLE_ENTRIES )
{
--
2.15.3.AMZN
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2020-01-07 12:07 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-07 12:06 [Xen-devel] [PATCH v5 0/7] Add alternative API for XEN PTEs Hongyan Xia
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 1/7] x86: move some xen mm function declarations Hongyan Xia
2020-01-07 12:13 ` Wei Liu
2020-01-07 13:09 ` Jan Beulich
2020-01-07 13:37 ` Wei Liu
2020-01-07 13:48 ` Xia, Hongyan
2020-01-07 14:03 ` Wei Liu
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 2/7] x86: introduce a new set of APIs to manage Xen page tables Hongyan Xia
2020-01-16 12:04 ` Jan Beulich
2020-01-27 14:33 ` Xia, Hongyan
2020-01-27 14:43 ` Jan Beulich
2020-01-27 15:07 ` Xia, Hongyan
2020-01-27 17:13 ` George Dunlap
2020-01-27 17:51 ` Wei Liu
2020-01-27 17:49 ` Wei Liu
2020-01-07 12:06 ` Hongyan Xia [this message]
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 4/7] x86/mm: introduce l{1, 2}t local variables to modify_xen_mappings Hongyan Xia
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 5/7] x86/mm: map_pages_to_xen would better have one exit path Hongyan Xia
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 6/7] x86/mm: make sure there is one exit path for modify_xen_mappings Hongyan Xia
2020-01-07 12:06 ` [Xen-devel] [PATCH v5 7/7] x86/mm: change pl*e to l*t in virt_to_xen_l*e Hongyan Xia
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=be3cd4478ca238809c40a8f3e2c8cc1ef247e57b.1578397252.git.hongyxia@amazon.com \
--to=hongyxia@amazon.com \
--cc=andrew.cooper3@citrix.com \
--cc=jbeulich@suse.com \
--cc=jgrall@amazon.com \
--cc=roger.pau@citrix.com \
--cc=wei.liu2@citrix.com \
--cc=wl@xen.org \
--cc=xen-devel@lists.xenproject.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).