[PATCH v3 20/21] KVM: arm64: Remove unused 'pgd' field from 'struct kvm_s2_mmu'

[Gavin Shan]

Hi Will,

On 8/25/20 7:39 PM, Will Deacon wrote:
> The stage-2 page-tables are entirely encapsulated by the 'pgt' field of
> 'struct kvm_s2_mmu', so remove the unused 'pgd' field.
> 
> Cc: Marc Zyngier <maz at kernel.org>
> Cc: Quentin Perret <qperret at google.com>
> Signed-off-by: Will Deacon <will at kernel.org>
> ---
>   arch/arm64/include/asm/kvm_host.h | 1 -
>   arch/arm64/kvm/mmu.c              | 2 --
>   2 files changed, 3 deletions(-)
> 

I think this might be folded into PATCH[18] as both patches are
simple enough. I'm not sure the changes introduced in PATCH[19]
prevent us doing this.

There is another question below.

Reviewed-by: Gavin Shan <gshan at redhat.com>

> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 0b7c702b2151..41caf29bd93c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -79,7 +79,6 @@ struct kvm_s2_mmu {
>   	 * for vEL1/EL0 with vHCR_EL2.VM == 0.  In that case, we use the
>   	 * canonical stage-2 page tables.
>   	 */
> -	pgd_t		*pgd;
>   	phys_addr_t	pgd_phys;
>   	struct kvm_pgtable *pgt;
>   
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index ddeec0b03666..f28e03dcb897 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -384,7 +384,6 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
>   	mmu->kvm = kvm;
>   	mmu->pgt = pgt;
>   	mmu->pgd_phys = __pa(pgt->pgd);
> -	mmu->pgd = (void *)pgt->pgd;
>   	mmu->vmid.vmid_gen = 0;
>   	return 0;
>   
> @@ -470,7 +469,6 @@ void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
>   	spin_lock(&kvm->mmu_lock);
>   	pgt = mmu->pgt;
>   	if (pgt) {
> -		mmu->pgd = NULL;
>   		mmu->pgd_phys = 0;
>   		mmu->pgt = NULL;
>   		free_percpu(mmu->last_vcpu_ran);
> 

I guess mmu->pgd_phys might be removed either because kvm_get_vttbr()
is the only consumer.

Thanks,
Gavin