linux-kernel - [PATCH] KVM: emulator: fix error code for _

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Date:	Mon, 27 Oct 2014 15:31:45 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	namit@...technion.ac.il, bp@...e.de
Subject: [PATCH] KVM: emulator: fix error code for __linearize

The error code for #GP and #SS is zero when the segment is used to
access an operand or an instruction.  It is only non-zero when
a segment register is being loaded; for limit checks this means
cases such as:

* for #GP, when RIP is beyond the limit on a far call (before the first
instruction is executed).  We do not implement this check, but it
would be in em_jmp_far/em_call_far.

* for #SS, if the new stack overflows during an inter-privilege-level
call to a non-conforming code segment.  We do not implement stack
switching at all.

So use an error code of zero.

Cc: Nadav Amit <namit@...technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/emulate.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 749f9fa38254..8aa66068712f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -711,9 +711,9 @@ static int __linearize(struct x86_emulate_ctxt *ctxt,
 	return X86EMUL_CONTINUE;
 bad:
 	if (addr.seg == VCPU_SREG_SS)
-		return emulate_ss(ctxt, sel);
+		return emulate_ss(ctxt, 0);
 	else
-		return emulate_gp(ctxt, sel);
+		return emulate_gp(ctxt, 0);
 }

 static int linearize(struct x86_emulate_ctxt *ctxt,
-- 
1.8.3.1

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