Re: [PATCH 02/28] KVM: x86/mmu: remove SPTE_PERM_MASK

[mlevitsk@redhat.com]

On Tue, 2026-05-05 at 21:52 +0200, Paolo Bonzini wrote:
> From: Jon Kohler <jon@nutanix.com>
> 
> SPTE_PERM_MASK is no longer referenced by anything in the kernel.

It might be worth adding a note saying that this macro has been unused for a long time.
(to help with backports) 

The last commit that referenced it was this one, if I am not mistaken:

commit 1441ca1494d74a2c9d6c9bd8dd633d9ebff1daba
Author: Junaid Shahid <junaids@google.com>
Date:   Fri Jul 22 19:43:16 2022 -0700

    kvm: x86: mmu: Drop the need_remote_flush() function
    
    This is only used by kvm_mmu_pte_write(), which no longer actually
    creates the new SPTE and instead just clears the old SPTE. So we
    just need to check if the old SPTE was shadow-present instead of
    calling need_remote_flush(). Hence we can drop this function. It was
    incomplete anyway as it didn't take access-tracking into account.
    
    This patch should not result in any functional change.
    
    Signed-off-by: Junaid Shahid <junaids@google.com>
    Reviewed-by: David Matlack <dmatlack@google.com>
    Reviewed-by: Sean Christopherson <seanjc@google.com>
    Message-Id: <20220723024316.2725328-1-junaids@google.com>
    Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>


> 
> Signed-off-by: Jon Kohler <jon@nutanix.com>
> Message-ID: <20251223054806.1611168-3-jon@nutanix.com>
> Tested-by: David Riley <d.riley@proxmox.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  arch/x86/kvm/mmu/spte.h | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
> index 91ce29fd6f1b..28086fa86fe0 100644
> --- a/arch/x86/kvm/mmu/spte.h
> +++ b/arch/x86/kvm/mmu/spte.h
> @@ -42,9 +42,6 @@ static_assert(SPTE_TDP_AD_ENABLED == 0);
>  #define SPTE_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
>  #endif
>  
> -#define SPTE_PERM_MASK (PT_PRESENT_MASK | PT_WRITABLE_MASK | shadow_user_mask \
> - | shadow_x_mask | shadow_nx_mask | shadow_me_mask)
> -
>  #define ACC_EXEC_MASK    1
>  #define ACC_WRITE_MASK   PT_WRITABLE_MASK
>  #define ACC_USER_MASK    PT_USER_MASK


Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Best regards,
	Maxim Levitsky