linux-kernel - [PATCH 2/9] KVM: x86: Emulator ignores LDTR/TR extended base on LLDT/LTR

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Message-Id: <1401723251-8034-3-git-send-email-namit@cs.technion.ac.il>
Date:	Mon,  2 Jun 2014 18:34:04 +0300
From:	Nadav Amit <namit@...technion.ac.il>
To:	pbonzini@...hat.com
Cc:	gleb@...nel.org, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Nadav Amit <namit@...technion.ac.il>
Subject: [PATCH 2/9] KVM: x86: Emulator ignores LDTR/TR extended base on LLDT/LTR

The current implementation ignores the LDTR/TR base high 32-bits on long-mode.
As a result the loaded segment descriptor may be incorrect.

Signed-off-by: Nadav Amit <namit@...technion.ac.il>
---
 arch/x86/kvm/emulate.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8ec4a3e..136088f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1422,6 +1422,7 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
 	ulong desc_addr;
 	int ret;
 	u16 dummy;
+	u32 base3 = 0;
 
 	memset(&seg_desc, 0, sizeof seg_desc);
 
@@ -1538,9 +1539,14 @@ static int __load_segment_descriptor(struct x86_emulate_ctxt *ctxt,
 		ret = write_segment_descriptor(ctxt, selector, &seg_desc);
 		if (ret != X86EMUL_CONTINUE)
 			return ret;
+	} else if (ctxt->mode == X86EMUL_MODE_PROT64) {
+		ret = ctxt->ops->read_std(ctxt, desc_addr+8, &base3,
+				sizeof(base3), &ctxt->exception);
+		if (ret != X86EMUL_CONTINUE)
+			return ret;
 	}
 load:
-	ctxt->ops->set_segment(ctxt, selector, &seg_desc, 0, seg);
+	ctxt->ops->set_segment(ctxt, selector, &seg_desc, base3, seg);
 	return X86EMUL_CONTINUE;
 exception:
 	emulate_exception(ctxt, err_vec, err_code, true);
-- 
1.9.1

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