From: Marcelo Tosatti <mtosatti@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, Nadav Amit <nadav.amit@gmail.com>
Subject: Re: [PATCH kvm-unit-tests] emulator: test 64-bit mov with immediate operand
Date: Thu, 13 Dec 2012 18:45:26 -0200 [thread overview]
Message-ID: <20121213204526.GA1529@amt.cnet> (raw)
In-Reply-To: <20121213122418.GA11016@redhat.com>
On Thu, Dec 13, 2012 at 02:24:18PM +0200, Gleb Natapov wrote:
> On Thu, Dec 13, 2012 at 01:11:55PM +0100, Paolo Bonzini wrote:
> > MOV immediate instruction (opcodes 0xB8-0xBF) may take 64-bit operand.
> > Some hypervisor implementations assumed the operand is 32-bit. This
> > should never happen because the instruction has no memory operand, but
> > (like the existing test_mmx_movq_mf) the testcase tricks the emulator
> > into executing one by mismatching the page tables and the corresponding
> > TLB entry.
> >
> BTW how the bug was found? Why instruction was emulated at all? May be
> there is bug somewhere that makes KVM emulate something it should not.
During switch to protected mode. SS.DPL=3, SS.RPL=0.
next prev parent reply other threads:[~2012-12-13 20:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-13 12:11 [PATCH kvm-unit-tests] emulator: test 64-bit mov with immediate operand Paolo Bonzini
2012-12-13 12:24 ` Gleb Natapov
2012-12-13 20:45 ` Marcelo Tosatti [this message]
2012-12-13 21:26 ` Gleb Natapov
2012-12-13 21:47 ` Marcelo Tosatti
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