From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xen.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Wei Liu <wei.liu2@citrix.com>, Jan Beulich <JBeulich@suse.com>
Subject: [PATCH for-4.7] x86/pv: Correctly fold vIOPL back into vcpu_guest_context
Date: Mon, 11 Apr 2016 10:03:55 +0100 [thread overview]
Message-ID: <1460365435-12325-1-git-send-email-andrew.cooper3@citrix.com> (raw)
c/s f71ecb6 "x86: introduce a new VMASSIST for architectural behaviour of
iopl" shifted the vcpu iopl field by 12, but didn't update the logic which
reconstructs the guests eflags for migration.
Existing guest kernels set a vIOPL of 1, to prevent them from faulting when
accessing IO ports. This bug manifests as a crash after migrate, as the vIOPL
reverts back to the default of 0, and the guest suffers an unexpected #GP
fault.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Wei Liu <wei.liu2@citrix.com>
---
xen/arch/x86/domctl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index cba1e37..6e709cb 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1512,7 +1512,7 @@ void arch_get_info_guest(struct vcpu *v, vcpu_guest_context_u c)
/* IOPL privileges are virtualised: merge back into returned eflags. */
BUG_ON((c(user_regs.eflags) & X86_EFLAGS_IOPL) != 0);
- c(user_regs.eflags |= v->arch.pv_vcpu.iopl << 12);
+ c(user_regs.eflags |= v->arch.pv_vcpu.iopl);
if ( !compat )
{
--
2.1.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
next reply other threads:[~2016-04-11 9:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-11 9:03 Andrew Cooper [this message]
2016-04-11 9:45 ` [PATCH for-4.7] x86/pv: Correctly fold vIOPL back into vcpu_guest_context Wei Liu
2016-04-11 14:08 ` Boris Ostrovsky
2016-04-11 14:22 ` Konrad Rzeszutek Wilk
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=1460365435-12325-1-git-send-email-andrew.cooper3@citrix.com \
--to=andrew.cooper3@citrix.com \
--cc=JBeulich@suse.com \
--cc=wei.liu2@citrix.com \
--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).