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

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Date:	Wed, 29 Jun 2016 10:18:34 +0200
From:	Paolo Bonzini <pbonzini@...hat.com>
To:	Xiao Guangrong <guangrong.xiao@...ux.intel.com>,
	Bandan Das <bsd@...hat.com>, kvm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] mmu: don't set the present bit unconditionally



On 29/06/2016 05:17, Xiao Guangrong wrote:
>>
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -2516,13 +2516,17 @@ static int set_spte(struct kvm_vcpu *vcpu, u64
>> *sptep,
>>               gfn_t gfn, kvm_pfn_t pfn, bool speculative,
>>               bool can_unsync, bool host_writable)
>>   {
>> -    u64 spte;
>> +    u64 spte = 0;
>>       int ret = 0;
>> +    struct kvm_mmu *context = &vcpu->arch.mmu;
>> +    bool execonly = !(context->guest_rsvd_check.bad_mt_xwr &
>> +              (1ull << VMX_EPT_EXECUTABLE_MASK));
> 
> Could we introduce a new field, say execonly, to "struct kvm_mmu"?
> That would make the code be more clearer.

Given how execonly is used, let's add shadow_present_mask instead.

Paolo