This is a note to let you know that I've just added the patch titled
KVM: X86: Fix operand/address-size during instruction decoding
to the 3.18-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-fix-operand-address-size-during-instruction-decoding.patch
and it can be found in the queue-3.18 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Thu Feb 1 14:48:12 CET 2018
From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Date: Sun, 5 Nov 2017 16:54:47 -0800
Subject: KVM: X86: Fix operand/address-size during instruction decoding
From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
[ Upstream commit 3853be2603191829b442b64dac6ae8ba0c027bf9 ]
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@xxxxxxxxxxxxxxxxx>
Tested-by: Pedro Fonseca <pfonseca@xxxxxxxxxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Nadav Amit <nadav.amit@xxxxxxxxx>
Cc: Pedro Fonseca <pfonseca@xxxxxxxxxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/emulate.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4385,6 +4385,8 @@ int x86_decode_insn(struct x86_emulate_c
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;
@@ -4403,6 +4405,11 @@ int x86_decode_insn(struct x86_emulate_c
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;
Patches currently in stable-queue which might be from wanpeng.li@xxxxxxxxxxx are
queue-3.18/kvm-x86-don-t-re-execute-instruction-when-not-passing-cr2-value.patch
queue-3.18/kvm-vmx-fix-rflags-cache-during-vcpu-reset.patch
queue-3.18/kvm-x86-fix-operand-address-size-during-instruction-decoding.patch
queue-3.18/kvm-x86-emulator-return-to-user-mode-on-l1-cpl-0-emulation-failure.patch