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>
Subject: [PATCH] x86/mm: avoid playing with directmap when self-snoop can be relied upon
Date: Tue, 20 Oct 2020 15:51:18 +0200 [thread overview]
Message-ID: <33f7168c-b177-eed5-14e8-5e7a38dee853@suse.com> (raw)
The set of systems affected by XSA-345 would have been smaller is we had
this in place already: When the processor is capable of dealing with
mismatched cacheability, there's no extra work we need to carry out.
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -795,6 +795,9 @@ static int update_xen_mappings(unsigned
unsigned long xen_va =
XEN_VIRT_START + ((mfn - PFN_DOWN(xen_phys_start)) << PAGE_SHIFT);
+ if ( boot_cpu_has(X86_FEATURE_XEN_SELFSNOOP) )
+ return 0;
+
if ( unlikely(alias) && cacheattr )
err = map_pages_to_xen(xen_va, _mfn(mfn), 1, 0);
if ( !err )
@@ -802,6 +805,7 @@ static int update_xen_mappings(unsigned
PAGE_HYPERVISOR | cacheattr_to_pte_flags(cacheattr));
if ( unlikely(alias) && !cacheattr && !err )
err = map_pages_to_xen(xen_va, _mfn(mfn), 1, PAGE_HYPERVISOR);
+
return err;
}
next reply other threads:[~2020-10-20 13:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-20 13:51 Jan Beulich [this message]
2020-10-21 15:23 ` [PATCH] x86/mm: avoid playing with directmap when self-snoop can be relied upon Roger Pau Monné
2020-10-22 7:29 ` Jan Beulich
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=33f7168c-b177-eed5-14e8-5e7a38dee853@suse.com \
--to=jbeulich@suse.com \
--cc=andrew.cooper3@citrix.com \
--cc=roger.pau@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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.