linux-kernel - Re: [PATCH 1/5] mmu: mark spte present if the x bit is set

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Message-ID: <862bf835-7937-5118-eafb-12adb3d1e7d3@redhat.com>
Date:	Tue, 5 Jul 2016 12:50:17 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Wanpeng Li <kernellwp@...il.com>
Cc:	Bandan Das <bsd@...hat.com>, kvm <kvm@...r.kernel.org>,
	guangrong.xiao@...ux.intel.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/5] mmu: mark spte present if the x bit is set



On 05/07/2016 05:06, Wanpeng Li wrote:
> 2016-06-29 4:49 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> [...]
>>
>> I think another way to write it is "(pte & 0xFFFFFFFFull) &&
>> !is_mmio_spte(pte)", since non-present/non-MMIO SPTEs never use bits
> 
> I misunderstand it here, this will also treat -W- EPT SPTEs as present, right?

-W- EPT SPTEs are present but invalid.  They should never happen unless
they are MMIO SPTEs (in which case !is_mmio_spte(pte) will return true
and the function will return false).

Paolo

> Regards,
> Wanpeng Li
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