linux-kernel - Re: [PATCH 3/5] mmu: don't set the present bit unconditionally

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Date:	Tue, 5 Jul 2016 12:50:50 +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 3/5] mmu: don't set the present bit unconditionally



On 05/07/2016 07:50, Wanpeng Li wrote:
>> > This needs a comment:
>> >
>> >         /*
>> >          * There are two cases in which execonly is false: 1) for
>> >          * non-EPT page tables, in which case we need to set the
>> >          * P bit; 2) for EPT page tables where an X-- page table
> In the scenario of non-EPT shadow page table and non-nested, the
> present bit can't be set any more since
> context->guest_rsvd_check.bad_mt_xwr is always 0.

This will be fixed with a new shadow_present_mask variable.

Paolo