Re: [PATCH v2 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate
From: Andrew Jones
Date: Wed Oct 06 2021 - 07:02:22 EST
On Mon, Oct 04, 2021 at 06:48:36PM +0100, Marc Zyngier wrote:
> kvm_pgtable_stage2_set_owner() could be generalised into a way
> to store up to 63 bits in the page tables, as long as we don't
> set bit 0.
>
> Let's just do that.
>
> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_pgtable.h | 12 ++++++-----
> arch/arm64/kvm/hyp/include/nvhe/mem_protect.h | 2 +-
> arch/arm64/kvm/hyp/nvhe/mem_protect.c | 11 ++++------
> arch/arm64/kvm/hyp/nvhe/setup.c | 10 +++++++++-
> arch/arm64/kvm/hyp/pgtable.c | 20 ++++++-------------
> 5 files changed, 27 insertions(+), 28 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
> index 027783829584..d4d3ae0b5edb 100644
> --- a/arch/arm64/include/asm/kvm_pgtable.h
> +++ b/arch/arm64/include/asm/kvm_pgtable.h
> @@ -329,14 +329,16 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> void *mc);
>
> /**
> - * kvm_pgtable_stage2_set_owner() - Unmap and annotate pages in the IPA space to
> - * track ownership.
> + * kvm_pgtable_stage2_annotate() - Unmap and annotate pages in the IPA space
> + * to track ownership (and more).
> * @pgt: Page-table structure initialised by kvm_pgtable_stage2_init*().
> * @addr: Base intermediate physical address to annotate.
> * @size: Size of the annotated range.
> * @mc: Cache of pre-allocated and zeroed memory from which to allocate
> * page-table pages.
> - * @owner_id: Unique identifier for the owner of the page.
> + * @annotation: A 63 bit value that will be stored in the page tables.
> + * @annotation[0] must be 0, and @annotation[63:1] is stored
> + * in the page tables.
> *
> * By default, all page-tables are owned by identifier 0. This function can be
> * used to mark portions of the IPA space as owned by other entities. When a
> @@ -345,8 +347,8 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> *
> * Return: 0 on success, negative error code on failure.
> */
> -int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> - void *mc, u8 owner_id);
> +int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
> + void *mc, kvm_pte_t annotation);
>
> /**
> * kvm_pgtable_stage2_unmap() - Remove a mapping from a guest stage-2 page-table.
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> index b58c910babaf..9d2ca173ea9a 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/mem_protect.h
> @@ -53,7 +53,7 @@ int __pkvm_host_share_hyp(u64 pfn);
>
> bool addr_is_memory(phys_addr_t phys);
> int host_stage2_idmap_locked(phys_addr_t addr, u64 size, enum kvm_pgtable_prot prot);
> -int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id);
> +int host_stage2_annotate_locked(phys_addr_t addr, u64 size, kvm_pte_t owner_id);
> int kvm_host_prepare_stage2(void *pgt_pool_base);
> void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt);
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index bacd493a4eac..8cd0c3bdb911 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -286,17 +286,14 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
> int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
> enum kvm_pgtable_prot prot)
> {
> - hyp_assert_lock_held(&host_kvm.lock);
> -
> return host_stage2_try(__host_stage2_idmap, addr, addr + size, prot);
> }
>
> -int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
> +int host_stage2_annotate_locked(phys_addr_t addr, u64 size,
> + kvm_pte_t annotation)
> {
> - hyp_assert_lock_held(&host_kvm.lock);
Hi Marc,
Why are the lock asserts getting dropped?
> -
> - return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
> - addr, size, &host_s2_pool, owner_id);
> + return host_stage2_try(kvm_pgtable_stage2_annotate, &host_kvm.pgt,
> + addr, size, &host_s2_pool, annotation);
> }
>
> static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
> diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
> index 57c27846320f..d489fb9b8c29 100644
> --- a/arch/arm64/kvm/hyp/nvhe/setup.c
> +++ b/arch/arm64/kvm/hyp/nvhe/setup.c
> @@ -159,6 +159,13 @@ static void hpool_put_page(void *addr)
> hyp_put_page(&hpool, addr);
> }
>
> +#define KVM_INVALID_PTE_OWNER_MASK GENMASK(9, 2)
> +
> +static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
> +{
> + return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
> +}
> +
> static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
> kvm_pte_t *ptep,
> enum kvm_pgtable_walk_flags flag,
> @@ -186,7 +193,8 @@ static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
> state = pkvm_getstate(kvm_pgtable_hyp_pte_prot(pte));
> switch (state) {
> case PKVM_PAGE_OWNED:
> - return host_stage2_set_owner_locked(phys, PAGE_SIZE, pkvm_hyp_id);
> + return host_stage2_annotate_locked(phys, PAGE_SIZE,
> + kvm_init_invalid_leaf_owner(pkvm_hyp_id));
> case PKVM_PAGE_SHARED_OWNED:
> prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_BORROWED);
> break;
> diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
> index 6bbfd952f0c5..4201e512da48 100644
> --- a/arch/arm64/kvm/hyp/pgtable.c
> +++ b/arch/arm64/kvm/hyp/pgtable.c
> @@ -46,9 +46,6 @@
> KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \
> KVM_PTE_LEAF_ATTR_HI_S2_XN)
>
> -#define KVM_INVALID_PTE_OWNER_MASK GENMASK(9, 2)
> -#define KVM_MAX_OWNER_ID 1
> -
> struct kvm_pgtable_walk_data {
> struct kvm_pgtable *pgt;
> struct kvm_pgtable_walker *walker;
> @@ -167,11 +164,6 @@ static kvm_pte_t kvm_init_valid_leaf_pte(u64 pa, kvm_pte_t attr, u32 level)
> return pte;
> }
>
> -static kvm_pte_t kvm_init_invalid_leaf_owner(u8 owner_id)
> -{
> - return FIELD_PREP(KVM_INVALID_PTE_OWNER_MASK, owner_id);
> -}
> -
> static int kvm_pgtable_visitor_cb(struct kvm_pgtable_walk_data *data, u64 addr,
> u32 level, kvm_pte_t *ptep,
> enum kvm_pgtable_walk_flags flag)
> @@ -503,7 +495,7 @@ void kvm_pgtable_hyp_destroy(struct kvm_pgtable *pgt)
> struct stage2_map_data {
> u64 phys;
> kvm_pte_t attr;
> - u8 owner_id;
> + u64 annotation;
>
> kvm_pte_t *anchor;
> kvm_pte_t *childp;
> @@ -670,7 +662,7 @@ static int stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
> if (kvm_phys_is_valid(phys))
> new = kvm_init_valid_leaf_pte(phys, data->attr, level);
> else
> - new = kvm_init_invalid_leaf_owner(data->owner_id);
> + new = data->annotation;
>
> if (stage2_pte_is_counted(old)) {
> /*
> @@ -859,8 +851,8 @@ int kvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size,
> return ret;
> }
>
> -int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> - void *mc, u8 owner_id)
> +int kvm_pgtable_stage2_annotate(struct kvm_pgtable *pgt, u64 addr, u64 size,
> + void *mc, kvm_pte_t annotation)
> {
> int ret;
> struct stage2_map_data map_data = {
> @@ -868,8 +860,8 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> .mmu = pgt->mmu,
> .memcache = mc,
> .mm_ops = pgt->mm_ops,
> - .owner_id = owner_id,
> .force_pte = true,
> + .annotation = annotation,
> };
> struct kvm_pgtable_walker walker = {
> .cb = stage2_map_walker,
> @@ -879,7 +871,7 @@ int kvm_pgtable_stage2_set_owner(struct kvm_pgtable *pgt, u64 addr, u64 size,
> .arg = &map_data,
> };
>
> - if (owner_id > KVM_MAX_OWNER_ID)
> + if (annotation & PTE_VALID)
> return -EINVAL;
>
> ret = kvm_pgtable_walk(pgt, addr, size, &walker);
> --
> 2.30.2
>
Thanks,
drew