From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpeng.li@hotmail.com>,
"Nadav Amit" <nadav.amit@gmail.com>,
"Pedro Fonseca" <pfonseca@cs.washington.edu>
Subject: [PATCH v5 1/3] KVM: X86: Fix operand/address-size during instruction decoding
Date: Thu, 2 Nov 2017 17:50:47 -0700 [thread overview]
Message-ID: <1509670249-4907-1-git-send-email-wanpeng.li@hotmail.com> (raw)
From: Wanpeng Li <wanpeng.li@hotmail.com>
Pedro reported:
During tests that we conducted on KVM, we noticed that executing a "PUSH %ES"
instruction under KVM produces different results on both memory and the SP
register depending on whether EPT support is enabled. With EPT the SP is
reduced by 4 bytes (and the written value is 0-padded) but without EPT support
it is only reduced by 2 bytes. The difference can be observed when the CS.DB
field is 1 (32-bit) but not when it's 0 (16-bit).
The internal segment descriptor cache exist even in real/vm8096 mode. The CS.D
also should be respected instead of just default operand/address-size/66H
prefix/67H prefix during instruction decoding. This patch fixes it by also
adjusting operand/address-size according to CS.D.
Reported-by: Pedro Fonseca <pfonseca@cs.washington.edu>
Tested-by: Pedro Fonseca <pfonseca@cs.washington.edu>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Cc: Pedro Fonseca <pfonseca@cs.washington.edu>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
v4 -> v5:
* cleanup patch subject/description
v3 -> v4:
* def_ad_bytes must be changed to 4
* separate X86EMUL_MODE_PROT16 altogether from the others
v2 -> v3:
* cleanup the codes
v1 -> v2:
* respect cs.d for real/vm8096, other modes have already
been considered in init_emulate_ctxt().
arch/x86/kvm/emulate.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 8079d14..b4a87de 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -5000,6 +5000,8 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
bool op_prefix = false;
bool has_seg_override = false;
struct opcode opcode;
+ u16 dummy;
+ struct desc_struct desc;
ctxt->memop.type = OP_NONE;
ctxt->memopp = NULL;
@@ -5018,6 +5020,11 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len)
switch (mode) {
case X86EMUL_MODE_REAL:
case X86EMUL_MODE_VM86:
+ def_op_bytes = def_ad_bytes = 2;
+ ctxt->ops->get_segment(ctxt, &dummy, &desc, NULL, VCPU_SREG_CS);
+ if (desc.d)
+ def_op_bytes = def_ad_bytes = 4;
+ break;
case X86EMUL_MODE_PROT16:
def_op_bytes = def_ad_bytes = 2;
break;
--
2.7.4
next reply other threads:[~2017-11-03 0:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-03 0:50 Wanpeng Li [this message]
2017-11-03 0:50 ` [PATCH v5 2/3] KVM: nVMX: Validate the IA32_BNDCFGS on nested VM-entry Wanpeng Li
[not found] ` <0b1d82f7-2fc6-9fc0-15a4-3500413814bd@oracle.com>
2017-11-03 6:40 ` Wanpeng Li
2017-11-03 17:13 ` Krish Sadhukhan
2017-11-03 17:54 ` Jim Mattson
2017-11-03 0:50 ` [PATCH v5 3/3] KVM: nVMX: Fix mmu context after VMLAUNCH/VMRESUME failure Wanpeng Li
2017-11-03 16:01 ` Jim Mattson
2017-11-04 0:07 ` Krish Sadhukhan
2017-11-08 21:47 ` Jim Mattson
2017-11-09 0:37 ` Wanpeng Li
2017-11-09 10:40 ` Paolo Bonzini
2017-11-09 10:47 ` Wanpeng Li
2017-11-09 11:05 ` Paolo Bonzini
2017-11-09 11:10 ` Wanpeng Li
2017-11-09 16:19 ` Jim Mattson
2018-02-05 18:44 ` Jim Mattson
2018-05-07 22:56 ` Jim Mattson
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