linux-kernel - Re: [PATCH] KVM: x86: don't expose syscall/sysret to intel 32-bit guest

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Message-ID: <564DBA60.2010707@redhat.com>
Date:	Thu, 19 Nov 2015 13:02:40 +0100
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Wanpeng Li <kernellwp@...il.com>
Cc:	Wanpeng li <wanpeng.li@...mail.com>, kvm <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] KVM: x86: don't expose syscall/sysret to intel 32-bit
 guest



On 19/11/2015 13:01, Wanpeng Li wrote:
> > This is not correct.  As far as I know, the SYSCALL bit is always
> > present in CPUID, even if the machine is running in 32-bit mode; CPUID
> > documentation (SDM Volume 2) explicitly documents bit 11 as "Bit 11:
> > SYSCALL/SYSRET available in 64-bit mode".
> 
> No, I try a 32-bit linux host kernel, cpuid tool shows that SYSCALL
> bit is not set.

Ok, let me try...

Paolo
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