From: Igor Druzhinin <igor.druzhinin@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: Igor Druzhinin <igor.druzhinin@citrix.com>,
kevin.tian@intel.com, wei.liu2@citrix.com, jbeulich@suse.com,
andrew.cooper3@citrix.com, jun.nakajima@intel.com,
roger.pau@citrix.com
Subject: [PATCH v2] x86/vmx: Fixup removals of MSR load/save list entries
Date: Thu, 4 Apr 2019 17:25:10 +0100 [thread overview]
Message-ID: <1554395110-22095-1-git-send-email-igor.druzhinin@citrix.com> (raw)
Commit 540d5422 ("x86/vmx: Support removing MSRs from the host/guest
load/save lists") introduced infrastructure finally exposed by
commit fd32dcfe ("x86/vmx: Don't leak EFER.NXE into guest context")
that led to a functional regression on Harpertown and earlier cores
(Gen 1 VT-x) due to MSR count being incorrectly set in VMCS.
As the result, as soon as guest EFER becomes equal to Xen EFER
(which eventually happens in almost every 64-bit VM) and its MSR
entry is supposed to be removed, a stale version of EFER is loaded
into a guest instead causing almost immediate guest failure.
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Igor Druzhinin <igor.druzhinin@citrix.com>
---
Changes in v2:
* better commit description as suggested
---
xen/arch/x86/hvm/vmx/vmcs.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 74f2a08..45d1849 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1490,15 +1490,15 @@ int vmx_del_msr(struct vcpu *v, uint32_t msr, enum vmx_msr_list_type type)
switch ( type )
{
case VMX_MSR_HOST:
- __vmwrite(VM_EXIT_MSR_LOAD_COUNT, vmx->host_msr_count--);
+ __vmwrite(VM_EXIT_MSR_LOAD_COUNT, --vmx->host_msr_count);
break;
case VMX_MSR_GUEST:
- __vmwrite(VM_EXIT_MSR_STORE_COUNT, vmx->msr_save_count--);
+ __vmwrite(VM_EXIT_MSR_STORE_COUNT, --vmx->msr_save_count);
/* Fallthrough */
case VMX_MSR_GUEST_LOADONLY:
- __vmwrite(VM_ENTRY_MSR_LOAD_COUNT, vmx->msr_load_count--);
+ __vmwrite(VM_ENTRY_MSR_LOAD_COUNT, --vmx->msr_load_count);
break;
}
--
2.7.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
reply other threads:[~2019-04-04 16:25 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
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=1554395110-22095-1-git-send-email-igor.druzhinin@citrix.com \
--to=igor.druzhinin@citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=jbeulich@suse.com \
--cc=jun.nakajima@intel.com \
--cc=kevin.tian@intel.com \
--cc=roger.pau@citrix.com \
--cc=wei.liu2@citrix.com \
--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).