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From: Wanpeng Li <kernellwp@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Bandan Das <bsd@redhat.com>, kvm <kvm@vger.kernel.org>,
	guangrong.xiao@linux.intel.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/5] mmu: don't set the present bit unconditionally
Date: Tue, 5 Jul 2016 13:50:39 +0800	[thread overview]
Message-ID: <CANRm+CzkiE-ZbuMJEHR8orS68vh81w+KFtRr33ug2kaDADWWeg@mail.gmail.com> (raw)
In-Reply-To: <60e083e8-596a-5641-fcb9-ede8bce32b58@redhat.com>

2016-06-28 16:57 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 28/06/2016 06:32, Bandan Das wrote:
>> +     bool execonly = !(context->guest_rsvd_check.bad_mt_xwr &
>> +                       (1ull << VMX_EPT_EXECUTABLE_MASK));
>>
>>       if (set_mmio_spte(vcpu, sptep, gfn, pfn, pte_access))
>>               return 0;
>>
>> -     spte = PT_PRESENT_MASK;
>> +     if (!execonly)
>> +             spte |= PT_PRESENT_MASK;
>
> 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.

Regards,
Wanpeng Li

  parent reply	other threads:[~2016-07-05  5:50 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-06-28  4:32 [PATCH 0/5] Add support for EPT execute only for nested hypervisors Bandan Das
2016-06-28  4:32 ` [PATCH 1/5] mmu: mark spte present if the x bit is set Bandan Das
2016-06-28  8:44   ` Paolo Bonzini
2016-06-28 17:33     ` Bandan Das
2016-06-28 20:17       ` Paolo Bonzini
2016-06-28 20:37         ` Bandan Das
2016-06-28 20:49           ` Paolo Bonzini
2016-06-28 21:04             ` Bandan Das
2016-06-29  3:01             ` Xiao Guangrong
2016-07-05  3:06             ` Wanpeng Li
2016-07-05 10:50               ` Paolo Bonzini
2016-07-05 11:29                 ` Wanpeng Li
2016-06-28  4:32 ` [PATCH 2/5] mmu: pass execonly value when initializing rsvd bits Bandan Das
2016-06-29  3:07   ` Xiao Guangrong
2016-06-28  4:32 ` [PATCH 3/5] mmu: don't set the present bit unconditionally Bandan Das
2016-06-28  8:57   ` Paolo Bonzini
2016-06-28 17:30     ` Bandan Das
2016-06-28 20:21       ` Paolo Bonzini
2016-07-05  5:50     ` Wanpeng Li [this message]
2016-07-05 10:50       ` Paolo Bonzini
2016-06-29  3:17   ` Xiao Guangrong
2016-06-29  8:18     ` Paolo Bonzini
2016-06-30  7:18       ` Xiao Guangrong
2016-06-28  4:32 ` [PATCH 4/5] mmu: remove is_present_gpte() Bandan Das
2016-06-28  4:32 ` [PATCH 5/5] nvmx: advertise support for ept execute only Bandan Das

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