Re: [PATCH v3 24/32] KVM: arm64: Reserve memory for host stage 2

Will Deacon
2021-03-04T19:51:50Z

On Tue, Mar 02, 2021 at 02:59:54PM +0000, Quentin Perret wrote:
> Extend the memory pool allocated for the hypervisor to include enough
> pages to map all of memory at page granularity for the host stage 2.
> While at it, also reserve some memory for device mappings.
>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
> arch/arm64/kvm/hyp/include/nvhe/mm.h | 23 ++++++++++++++++++++++-
> arch/arm64/kvm/hyp/nvhe/setup.c | 12 ++++++++++++
> arch/arm64/kvm/hyp/reserved_mem.c | 2 ++
> 3 files changed, 36 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mm.h b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> index ac0f7fcffd08..411a35db949c 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mm.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mm.h
> @@ -53,7 +53,7 @@ static inline unsigned long __hyp_pgtable_max_pages(unsigned long nr_pages)
> return total;
> }
>
> -static inline unsigned long hyp_s1_pgtable_pages(void)
> +static inline unsigned long __hyp_pgtable_total_pages(void)
> {
> unsigned long res = 0, i;
>
> @@ -63,9 +63,30 @@ static inline unsigned long hyp_s1_pgtable_pages(void)
> res += __hyp_pgtable_max_pages(reg->size >> PAGE_SHIFT);
> }
>
> + return res;
> +}
> +
> +static inline unsigned long hyp_s1_pgtable_pages(void)
> +{
> + unsigned long res;
> +
> + res = __hyp_pgtable_total_pages();
> +
> /* Allow 1 GiB for private mappings */
> res += __hyp_pgtable_max_pages(SZ_1G >> PAGE_SHIFT);
>
> return res;
> }
> +
> +static inline unsigned long host_s2_mem_pgtable_pages(void)
> +{
> + return __hyp_pgtable_total_pages() + 16;

Is this 16 due to the possibility of a concatenated pgd? If so, please add
a comment to that effect.

With that:

Acked-by: Will Deacon <will@kernel.org>

Will