From: Malcolm Crossley <malcolm.crossley@citrix.com>
To: george.dunlap@eu.citrix.com, keir@xen.org, jbeulich@suse.com,
andrew.cooper3@citrix.com
Cc: Malcolm Crossley <malcolm.crossley@citrix.com>, xen-devel@lists.xen.org
Subject: [PATCH] xen: Restore p2m_access_t enum order to allow bitmask semantics
Date: Tue, 8 Mar 2016 15:30:28 +0000 [thread overview]
Message-ID: <1457451028-3808-1-git-send-email-malcolm.crossley@citrix.com> (raw)
Nested hap code assumed implict bitmask semantics of the p2m_access_t
enum prior to C/S 4c63692d7c38c5ac414fe97f8ef37b66e05abe5c
The change to the enum ordering broke this assumption and caused functional
problems for the nested hap code. As it may be error prone to audit and find
all other p2m_access users assuming bitmask semantics, instead restore the
previous enum order and make it explict that bitmask semantics are to be
preserved for the read, write and execute access types.
Signed-off-by: Malcolm Crossley <malcolm.crossley@citrix.com>
---
xen/arch/x86/mm/hap/nested_hap.c | 2 +-
xen/include/xen/p2m-common.h | 17 +++++++++--------
2 files changed, 10 insertions(+), 9 deletions(-)
diff --git a/xen/arch/x86/mm/hap/nested_hap.c b/xen/arch/x86/mm/hap/nested_hap.c
index 0dbae13..9cee5a0 100644
--- a/xen/arch/x86/mm/hap/nested_hap.c
+++ b/xen/arch/x86/mm/hap/nested_hap.c
@@ -263,7 +263,7 @@ nestedhvm_hap_nested_page_fault(struct vcpu *v, paddr_t *L2_gpa,
switch ( p2ma_10 )
{
- case p2m_access_rwx ... p2m_access_n:
+ case p2m_access_n ... p2m_access_rwx:
break;
case p2m_access_rx2rw:
p2ma_10 = p2m_access_rx;
diff --git a/xen/include/xen/p2m-common.h b/xen/include/xen/p2m-common.h
index 8b70459..6374a5b 100644
--- a/xen/include/xen/p2m-common.h
+++ b/xen/include/xen/p2m-common.h
@@ -15,14 +15,15 @@
* default.
*/
typedef enum {
- p2m_access_rwx = 0, /* The default access type when not used. */
- p2m_access_wx = 1,
- p2m_access_rx = 2,
- p2m_access_x = 3,
- p2m_access_rw = 4,
- p2m_access_w = 5,
- p2m_access_r = 6,
- p2m_access_n = 7, /* No access allowed. */
+ /* Code uses bottom three bits with bitmask semantics */
+ p2m_access_n = 0, /* No access allowed. */
+ p2m_access_r = 1 << 0,
+ p2m_access_w = 1 << 1,
+ p2m_access_x = 1 << 2,
+ p2m_access_rw = p2m_access_r | p2m_access_w,
+ p2m_access_rx = p2m_access_r | p2m_access_x,
+ p2m_access_wx = p2m_access_w | p2m_access_x,
+ p2m_access_rwx = p2m_access_r | p2m_access_w | p2m_access_x,
p2m_access_rx2rw = 8, /* Special: page goes from RX to RW on write */
p2m_access_n2rwx = 9, /* Special: page goes from N to RWX on access, *
--
1.7.12.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next reply other threads:[~2016-03-08 15:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-08 15:30 Malcolm Crossley [this message]
2016-03-08 15:36 ` [PATCH] xen: Restore p2m_access_t enum order to allow bitmask semantics Andrew Cooper
2016-03-08 15:52 ` Jan Beulich
2016-03-08 15:58 ` Tamas K Lengyel
2016-03-09 16:30 ` George Dunlap
2016-03-10 20:48 ` Tamas K Lengyel
2016-03-11 8:53 ` Malcolm Crossley
2016-03-14 18:12 ` George Dunlap
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=1457451028-3808-1-git-send-email-malcolm.crossley@citrix.com \
--to=malcolm.crossley@citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=george.dunlap@eu.citrix.com \
--cc=jbeulich@suse.com \
--cc=keir@xen.org \
--cc=xen-devel@lists.xen.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).