On Wed, 07/13 11:20, Paolo Bonzini wrote:
> 
> 
> On 13/07/2016 00:18, Bandan Das wrote:
> > v1 of this series posted at https://lkml.org/lkml/2016/6/28/7
> > 
> > Changes since v1:
> >  - 1/5 : modify is_shadow_present_pte to check against 0xffffffff
> >    Reasoning provided in commit message.
> >  - 2/5 : Removed 2/5 from v1 since kvm doesn't use execute only.
> >    3/5 from v1 is now 2/5. Introduce shadow_present_mask that
> >    signifies whether ept execute only is supported. Add/remove some
> >    comments as suggested in v1.
> >  - 3/5 : 4/5 from v1 is now 3/5.
> >  - 4/5 : update_permission_bitmask now sets u=1 only if host doesn't
> >    support ept execute only.
> >  - 5/5 : No change
> 
> These are the diffs I have after review, do they look okay?
> 
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 190c0559c221..bd2535fdb9eb 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -2524,11 +2524,10 @@ static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
>               return 0;
>  
>       /*
> -      * In the non-EPT case, execonly is not valid and so
> -      * the following line is equivalent to spte |= PT_PRESENT_MASK.
>        * For the EPT case, shadow_present_mask is 0 if hardware
> -      * supports it and we honor whatever way the guest set it.
> -      * See: FNAME(gpte_access) in paging_tmpl.h
> +      * supports exec-only page table entries.  In that case,
> +      * ACC_USER_MASK and shadow_user_mask are used to represent
> +      * read access.  See FNAME(gpte_access) in paging_tmpl.h.
>        */
>       spte |= shadow_present_mask;
>       if (!speculative)
> @@ -3923,9 +3922,6 @@ static void update_permission_bitmask(struct kvm_vcpu 
> *vcpu,
>                                *   clearer.
>                                */
>                               smap = cr4_smap && u && !uf && !ff;
> -                     } else {
> -                             if (shadow_present_mask)
> -                                     u = 1;
>                       }
>  
>                       fault = (ff && !x) || (uf && !u) || (wf && !w) ||
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 576c47cda1a3..dfef081e76c0 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -6120,12 +6120,14 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
>       gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS);
>       trace_kvm_page_fault(gpa, exit_qualification);
>  
> -     /* It is a write fault? */
> +     /* it is a read fault? */
> +     error_code = (exit_qualification << 2) & PFERR_USER_MASK;
> +     /* it is a write fault? */
>       error_code = exit_qualification & PFERR_WRITE_MASK;

Did you mean s/=/|=/ for this line?

Fam

>       /* It is a fetch fault? */
>       error_code |= (exit_qualification << 2) & PFERR_FETCH_MASK;
>       /* ept page table is present? */
> -     error_code |= (exit_qualification >> 3) & PFERR_PRESENT_MASK;
> +     error_code |= (exit_qualification & 0x38) != 0;
>  
>       vcpu->arch.exit_qualification = exit_qualification;
>  
> @@ -6474,8 +6476,7 @@ static __init int hardware_setup(void)
>                       (enable_ept_ad_bits) ? VMX_EPT_DIRTY_BIT : 0ull,
>                       0ull, VMX_EPT_EXECUTABLE_MASK,
>                       cpu_has_vmx_ept_execute_only() ?
> -                                   0ull : PT_PRESENT_MASK);
> -             BUILD_BUG_ON(PT_PRESENT_MASK != VMX_EPT_READABLE_MASK);
> +                                   0ull : VMX_EPT_READABLE_MASK);
>               ept_set_mmio_spte_mask();
>               kvm_enable_tdp();
>       } else
> 
> --
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