From: Jan Beulich <jbeulich@suse.com>
To: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>,
"George Dunlap" <george.dunlap@citrix.com>,
"Tim Deegan" <tim@xen.org>
Subject: [PATCH v4 2/3] x86/shadow: re-use variables in shadow_get_page_from_l1e()
Date: Fri, 23 Apr 2021 12:53:24 +0200 [thread overview]
Message-ID: <a7817f29-9a07-ab20-2224-999e75537fe3@suse.com> (raw)
In-Reply-To: <3e7ad009-f062-d58a-9380-103ce1573a73@suse.com>
There's little point in doing multiple mfn_to_page() or page_get_owner()
on all the same MFN. Calculate them once at the start of the function.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Tim Deegan <tim@xen.org>
---
v5: Integrate into series. Re-base.
v2: Re-base.
--- a/xen/arch/x86/mm/shadow/set.c
+++ b/xen/arch/x86/mm/shadow/set.c
@@ -88,19 +88,25 @@ static int inline
shadow_get_page_from_l1e(shadow_l1e_t sl1e, struct domain *d, p2m_type_t type)
{
int res;
- mfn_t mfn;
- struct domain *owner;
+ mfn_t mfn = shadow_l1e_get_mfn(sl1e);
+ const struct page_info *pg = NULL;
+ struct domain *owner = NULL;
ASSERT(!sh_l1e_is_magic(sl1e));
ASSERT(shadow_mode_refcounts(d));
+ if ( mfn_valid(mfn) )
+ {
+ pg = mfn_to_page(mfn);
+ owner = page_get_owner(pg);
+ }
+
/*
* Check whether refcounting is suppressed on this page. For example,
* VMX'es APIC access MFN is just a surrogate page. It doesn't actually
* get accessed, and hence there's no need to refcount it.
*/
- mfn = shadow_l1e_get_mfn(sl1e);
- if ( mfn_valid(mfn) && page_refcounting_suppressed(mfn_to_page(mfn)) )
+ if ( pg && page_refcounting_suppressed(pg) )
return 0;
res = get_page_from_l1e(sl1e, d, d);
@@ -111,9 +117,7 @@ shadow_get_page_from_l1e(shadow_l1e_t sl
*/
if ( unlikely(res < 0) &&
!shadow_mode_translate(d) &&
- mfn_valid(mfn = shadow_l1e_get_mfn(sl1e)) &&
- (owner = page_get_owner(mfn_to_page(mfn))) &&
- (d != owner) )
+ owner && (d != owner) )
{
res = xsm_priv_mapping(XSM_TARGET, d, owner);
if ( !res )
@@ -136,9 +140,8 @@ shadow_get_page_from_l1e(shadow_l1e_t sl
* already have checked that we're supposed to have access, so
* we can just grab a reference directly.
*/
- mfn = shadow_l1e_get_mfn(sl1e);
- if ( mfn_valid(mfn) )
- res = get_page_from_l1e(sl1e, d, page_get_owner(mfn_to_page(mfn)));
+ if ( owner )
+ res = get_page_from_l1e(sl1e, d, owner);
}
if ( unlikely(res < 0) )
next prev parent reply other threads:[~2021-04-23 10:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-22 10:55 [PATCH v3 0/2] VMX: apic access page handling adjustments Jan Beulich
2021-02-22 10:56 ` [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page Jan Beulich
2021-02-22 11:25 ` Ian Jackson
2021-02-22 14:05 ` Jan Beulich
2021-02-22 17:17 ` Ian Jackson
2021-02-22 12:15 ` Roger Pau Monné
2021-02-25 8:44 ` Jan Beulich
2021-02-26 7:06 ` Tian, Kevin
2021-02-22 10:57 ` [PATCH v3 2/2] VMX: use a single, global " Jan Beulich
2021-03-01 2:34 ` Tian, Kevin
2021-03-01 8:18 ` Jan Beulich
2021-04-12 10:40 ` [PATCH v4] " Jan Beulich
2021-04-12 15:31 ` Roger Pau Monné
2021-04-13 9:24 ` Jan Beulich
2021-04-13 10:18 ` Roger Pau Monné
2021-04-13 12:03 ` Jan Beulich
2021-04-13 13:03 ` Roger Pau Monné
2021-04-17 19:24 ` Tim Deegan
2021-04-19 11:25 ` Jan Beulich
2021-04-22 7:42 ` Tim Deegan
2021-04-22 9:38 ` Jan Beulich
2021-04-22 15:05 ` Tim Deegan
2021-04-23 10:51 ` [PATCH v4 0/3] VMX APIC access page and shadow adjustments Jan Beulich
2021-04-23 10:52 ` [PATCH v4 1/3] VMX: use a single, global APIC access page Jan Beulich
2021-04-23 14:17 ` Roger Pau Monné
2021-04-23 14:42 ` Jan Beulich
2021-04-26 17:55 ` Tim Deegan
2021-04-25 1:27 ` Tian, Kevin
2021-04-26 17:53 ` Tim Deegan
2021-04-23 10:53 ` Jan Beulich [this message]
2021-04-23 10:54 ` [PATCH v4 3/3] x86/shadow: streamline shadow_get_page_from_l1e() Jan Beulich
2021-04-23 11:00 ` Really v5 (was: [PATCH v4 0/3] VMX APIC access page and shadow adjustments) Jan Beulich
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