linux-kernel - Re: [PATCH v3 03/18] KVM: arm64: Make hyp

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Message-ID: <CA+EHjTznFMF77kfUTkMeRpHnz9HAD1gSw6Do6tQvYSJ_jXG3gg@mail.gmail.com>
Date: Tue, 17 Dec 2024 08:43:45 +0000
From: Fuad Tabba <tabba@...gle.com>
To: Quentin Perret <qperret@...gle.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Vincent Donnefort <vdonnefort@...gle.com>, 
	Sebastian Ene <sebastianene@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 03/18] KVM: arm64: Make hyp_page::order a u8

On Mon, 16 Dec 2024 at 17:58, Quentin Perret <qperret@...gle.com> wrote:
>
> We don't need 16 bits to store the hyp page order, and we'll need some
> bits to store page ownership data soon, so let's reduce the order
> member.
>
> Signed-off-by: Quentin Perret <qperret@...gle.com>

Reviewed-by: Fuad Tabba <tabba@...gle.com>

Cheers,
/fuad

> ---
>  arch/arm64/kvm/hyp/include/nvhe/gfp.h    |  6 +++---
>  arch/arm64/kvm/hyp/include/nvhe/memory.h |  5 +++--
>  arch/arm64/kvm/hyp/nvhe/page_alloc.c     | 14 +++++++-------
>  3 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/gfp.h b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
> index 97c527ef53c2..f1725bad6331 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/gfp.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/gfp.h
> @@ -7,7 +7,7 @@
>  #include <nvhe/memory.h>
>  #include <nvhe/spinlock.h>
>
> -#define HYP_NO_ORDER   USHRT_MAX
> +#define HYP_NO_ORDER   0xff
>
>  struct hyp_pool {
>         /*
> @@ -19,11 +19,11 @@ struct hyp_pool {
>         struct list_head free_area[NR_PAGE_ORDERS];
>         phys_addr_t range_start;
>         phys_addr_t range_end;
> -       unsigned short max_order;
> +       u8 max_order;
>  };
>
>  /* Allocation */
> -void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order);
> +void *hyp_alloc_pages(struct hyp_pool *pool, u8 order);
>  void hyp_split_page(struct hyp_page *page);
>  void hyp_get_page(struct hyp_pool *pool, void *addr);
>  void hyp_put_page(struct hyp_pool *pool, void *addr);
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/memory.h b/arch/arm64/kvm/hyp/include/nvhe/memory.h
> index c84b24234ac7..45b8d1840aa4 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/memory.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/memory.h
> @@ -41,8 +41,9 @@ static inline enum pkvm_page_state pkvm_getstate(enum kvm_pgtable_prot prot)
>  }
>
>  struct hyp_page {
> -       unsigned short refcount;
> -       unsigned short order;
> +       u16 refcount;
> +       u8 order;
> +       u8 reserved;
>  };
>
>  extern u64 __hyp_vmemmap;
> diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
> index e691290d3765..a1eb27a1a747 100644
> --- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
> +++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
> @@ -32,7 +32,7 @@ u64 __hyp_vmemmap;
>   */
>  static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
>                                              struct hyp_page *p,
> -                                            unsigned short order)
> +                                            u8 order)
>  {
>         phys_addr_t addr = hyp_page_to_phys(p);
>
> @@ -51,7 +51,7 @@ static struct hyp_page *__find_buddy_nocheck(struct hyp_pool *pool,
>  /* Find a buddy page currently available for allocation */
>  static struct hyp_page *__find_buddy_avail(struct hyp_pool *pool,
>                                            struct hyp_page *p,
> -                                          unsigned short order)
> +                                          u8 order)
>  {
>         struct hyp_page *buddy = __find_buddy_nocheck(pool, p, order);
>
> @@ -94,7 +94,7 @@ static void __hyp_attach_page(struct hyp_pool *pool,
>                               struct hyp_page *p)
>  {
>         phys_addr_t phys = hyp_page_to_phys(p);
> -       unsigned short order = p->order;
> +       u8 order = p->order;
>         struct hyp_page *buddy;
>
>         memset(hyp_page_to_virt(p), 0, PAGE_SIZE << p->order);
> @@ -129,7 +129,7 @@ static void __hyp_attach_page(struct hyp_pool *pool,
>
>  static struct hyp_page *__hyp_extract_page(struct hyp_pool *pool,
>                                            struct hyp_page *p,
> -                                          unsigned short order)
> +                                          u8 order)
>  {
>         struct hyp_page *buddy;
>
> @@ -183,7 +183,7 @@ void hyp_get_page(struct hyp_pool *pool, void *addr)
>
>  void hyp_split_page(struct hyp_page *p)
>  {
> -       unsigned short order = p->order;
> +       u8 order = p->order;
>         unsigned int i;
>
>         p->order = 0;
> @@ -195,10 +195,10 @@ void hyp_split_page(struct hyp_page *p)
>         }
>  }
>
> -void *hyp_alloc_pages(struct hyp_pool *pool, unsigned short order)
> +void *hyp_alloc_pages(struct hyp_pool *pool, u8 order)
>  {
> -       unsigned short i = order;
>         struct hyp_page *p;
> +       u8 i = order;
>
>         hyp_spin_lock(&pool->lock);
>
> --
> 2.47.1.613.gc27f4b7a9f-goog
>