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List: xen-cvs
Subject: [Xen-changelog] [xen stable-4.7] x86/hvm: Clobber %cs.L when LME becomes set
From: patchbot () xen ! org
Date: 2016-10-27 10:22:32
Message-ID: E1bzhpQ-0000F8-PE () xenbits ! xenproject ! org
[Download RAW message or body]
commit a91344a3142fea5e826ac8b3ef0b623699bf5f71
Author: Andrew Cooper <andrew.cooper3@citrix.com>
AuthorDate: Tue Oct 25 17:11:08 2016 +0200
Commit: Jan Beulich <jbeulich@suse.com>
CommitDate: Tue Oct 25 17:11:08 2016 +0200
x86/hvm: Clobber %cs.L when LME becomes set
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: ed00f1761689ac7b9c074e9084c81e47c25d460c
master date: 2016-10-14 12:44:29 +0100
---
xen/arch/x86/hvm/hvm.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 80bfabf..69580cc 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2012,6 +2012,30 @@ int hvm_set_efer(uint64_t value)
return X86EMUL_EXCEPTION;
}
+ if ( (value & EFER_LME) && !(v->arch.hvm_vcpu.guest_efer & EFER_LME) )
+ {
+ struct segment_register cs;
+
+ hvm_get_segment_register(v, x86_seg_cs, &cs);
+
+ /*
+ * %cs may be loaded with both .D and .L set in legacy mode, and both
+ * are captured in the VMCS/VMCB.
+ *
+ * If a guest does this and then tries to transition into long mode,
+ * the vmentry from setting LME fails due to invalid guest state,
+ * because %cr0.PG is still clear.
+ *
+ * When LME becomes set, clobber %cs.L to keep the guest firmly in
+ * compatibility mode until it reloads %cs itself.
+ */
+ if ( cs.attr.fields.l )
+ {
+ cs.attr.fields.l = 0;
+ hvm_set_segment_register(v, x86_seg_cs, &cs);
+ }
+ }
+
if ( nestedhvm_enabled(v->domain) && cpu_has_svm &&
((value & EFER_SVME) == 0 ) &&
((value ^ v->arch.hvm_vcpu.guest_efer) & EFER_SVME) )
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.7
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