[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [RFC PATCH v1 6/7] iommu/arm: ipmmu-vmsa: Deallocate page table asynchronously
From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> This is the PoC how to optimize page table deallocation sequence by splitting it into separate chunks. Use iommu_pt_cleanup_list to queue pages that need to be handled and freed next time. Use free_page_table platform callback to dequeue pages. Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> CC: Julien Grall <julien.grall@xxxxxxx> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx> --- xen/drivers/passthrough/arm/io-pgtable-arm.c | 94 +++++++++++++++++++++++++--- xen/drivers/passthrough/arm/io-pgtable.c | 5 +- xen/drivers/passthrough/arm/io-pgtable.h | 4 +- xen/drivers/passthrough/arm/ipmmu-vmsa.c | 33 ++++++++-- 4 files changed, 119 insertions(+), 17 deletions(-) diff --git a/xen/drivers/passthrough/arm/io-pgtable-arm.c b/xen/drivers/passthrough/arm/io-pgtable-arm.c index c98caa3..7673fda 100644 --- a/xen/drivers/passthrough/arm/io-pgtable-arm.c +++ b/xen/drivers/passthrough/arm/io-pgtable-arm.c @@ -254,6 +254,10 @@ struct arm_lpae_io_pgtable { /* Xen: We deal with domain pages. */ struct page_info *pgd; + /* Xen: To indicate that deallocation sequence is in progress. */ + bool_t cleanup; + /* Xen: To count allocated domain pages. */ + unsigned int page_count; }; typedef u64 arm_lpae_iopte; @@ -329,7 +333,7 @@ static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte, #endif static struct page_info *__arm_lpae_alloc_pages(size_t size, gfp_t gfp, - struct io_pgtable_cfg *cfg) + struct arm_lpae_io_pgtable *data) { struct page_info *pages; unsigned int order = get_order_from_bytes(size); @@ -342,15 +346,21 @@ static struct page_info *__arm_lpae_alloc_pages(size_t size, gfp_t gfp, for (i = 0; i < (1 << order); i ++) clear_and_clean_page(pages + i); + data->page_count += (1<<order); + return pages; } static void __arm_lpae_free_pages(struct page_info *pages, size_t size, - struct io_pgtable_cfg *cfg) + struct arm_lpae_io_pgtable *data) { unsigned int order = get_order_from_bytes(size); + BUG_ON((int)data->page_count <= 0); + free_domheap_pages(pages, order); + + data->page_count -= (1<<order); } static void __arm_lpae_set_pte(arm_lpae_iopte *ptep, arm_lpae_iopte pte, @@ -434,7 +444,7 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable *data, unsigned long iova, pte = *ptep; if (!pte) { page = __arm_lpae_alloc_pages(ARM_LPAE_GRANULE(data), - GFP_ATOMIC, cfg); + GFP_ATOMIC, data); if (!page) return -ENOMEM; @@ -526,6 +536,46 @@ static int arm_lpae_map(struct io_pgtable_ops *ops, unsigned long iova, return ret; } +static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl, + struct page_info *page); + +/* + * TODO: We have reused unused at the moment "page->pad" variable for + * storing "data" pointer we need during deallocation sequence. The current + * free_page_table platform callback carries the only one "page" argument. + * To perform required calculations with the current (generic) allocator + * implementation we are highly interested in the following fields: + * - data->levels + * - data->pg_shift + * - data->pgd_size + * But, this necessity might be avoided if we integrate allocator code with + * IPMMU-VMSA driver. And these variables will turn into the + * corresponding #define-s. + */ +static void __arm_lpae_free_next_pgtable(struct arm_lpae_io_pgtable *data, + int lvl, struct page_info *page) +{ + if (!data->cleanup) { + /* + * We are here during normal page table maintenance. Just call + * __arm_lpae_free_pgtable(), what we actually had to call. + */ + __arm_lpae_free_pgtable(data, lvl, page); + } else { + /* + * The page table deallocation sequence is in progress. Use some fields + * in struct page_info to pass arguments we will need during handling + * this page back. Queue page to list. + */ + PFN_ORDER(page) = lvl; + page->pad = (u64)&data->iop.ops; + + spin_lock(&iommu_pt_cleanup_lock); + page_list_add_tail(page, &iommu_pt_cleanup_list); + spin_unlock(&iommu_pt_cleanup_lock); + } +} + /* Xen: We deal with domain pages. */ static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl, struct page_info *page) @@ -553,19 +603,41 @@ static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl, if (!pte || iopte_leaf(pte, lvl)) continue; - __arm_lpae_free_pgtable(data, lvl + 1, iopte_deref(pte, data)); + __arm_lpae_free_next_pgtable(data, lvl + 1, iopte_deref(pte, data)); } unmap_domain_page(start); - __arm_lpae_free_pages(page, table_size, &data->iop.cfg); + __arm_lpae_free_pages(page, table_size, data); } -static void arm_lpae_free_pgtable(struct io_pgtable *iop) +/* + * We added extra "page" argument since we want to know what page is processed + * at the moment and should be freed. + * */ +static void arm_lpae_free_pgtable(struct io_pgtable *iop, struct page_info *page) { struct arm_lpae_io_pgtable *data = io_pgtable_to_data(iop); + int lvl; - __arm_lpae_free_pgtable(data, ARM_LPAE_START_LVL(data), data->pgd); - kfree(data); + if (!data->cleanup) { + /* Start page table deallocation sequence from the first level. */ + data->cleanup = true; + lvl = ARM_LPAE_START_LVL(data); + } else { + /* Retrieve the level to continue deallocation sequence from. */ + lvl = PFN_ORDER(page); + PFN_ORDER(page) = 0; + page->pad = 0; + } + + __arm_lpae_free_pgtable(data, lvl, page); + + /* + * Seems, we have already deallocated all pages, so it is time + * to release unfreed resource. + */ + if (!data->page_count) + kfree(data); } /* Xen: We deal with domain pages. */ @@ -889,8 +961,12 @@ arm_64_lpae_alloc_pgtable_s1(struct io_pgtable_cfg *cfg, void *cookie) cfg->arm_lpae_s1_cfg.mair[0] = reg; cfg->arm_lpae_s1_cfg.mair[1] = 0; + /* Just to be sure */ + data->cleanup = false; + data->page_count = 0; + /* Looking good; allocate a pgd */ - data->pgd = __arm_lpae_alloc_pages(data->pgd_size, GFP_KERNEL, cfg); + data->pgd = __arm_lpae_alloc_pages(data->pgd_size, GFP_KERNEL, data); if (!data->pgd) goto out_free_data; diff --git a/xen/drivers/passthrough/arm/io-pgtable.c b/xen/drivers/passthrough/arm/io-pgtable.c index bfc7020..e25d731 100644 --- a/xen/drivers/passthrough/arm/io-pgtable.c +++ b/xen/drivers/passthrough/arm/io-pgtable.c @@ -77,7 +77,7 @@ struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, * It is the IOMMU driver's responsibility to ensure that the page table * is no longer accessible to the walker by this point. */ -void free_io_pgtable_ops(struct io_pgtable_ops *ops) +void free_io_pgtable_ops(struct io_pgtable_ops *ops, struct page_info *page) { struct io_pgtable *iop; @@ -86,5 +86,6 @@ void free_io_pgtable_ops(struct io_pgtable_ops *ops) iop = container_of(ops, struct io_pgtable, ops); io_pgtable_tlb_flush_all(iop); - io_pgtable_init_table[iop->fmt]->free(iop); + iop->cookie = NULL; + io_pgtable_init_table[iop->fmt]->free(iop, page); } diff --git a/xen/drivers/passthrough/arm/io-pgtable.h b/xen/drivers/passthrough/arm/io-pgtable.h index fb81fcf..df0e21b 100644 --- a/xen/drivers/passthrough/arm/io-pgtable.h +++ b/xen/drivers/passthrough/arm/io-pgtable.h @@ -144,7 +144,7 @@ struct io_pgtable_ops *alloc_io_pgtable_ops(enum io_pgtable_fmt fmt, * * @ops: The ops returned from alloc_io_pgtable_ops. */ -void free_io_pgtable_ops(struct io_pgtable_ops *ops); +void free_io_pgtable_ops(struct io_pgtable_ops *ops, struct page_info *page); /* @@ -201,7 +201,7 @@ static inline void io_pgtable_tlb_sync(struct io_pgtable *iop) */ struct io_pgtable_init_fns { struct io_pgtable *(*alloc)(struct io_pgtable_cfg *cfg, void *cookie); - void (*free)(struct io_pgtable *iop); + void (*free)(struct io_pgtable *iop, struct page_info *page); }; extern struct io_pgtable_init_fns io_pgtable_arm_32_lpae_s1_init_fns; diff --git a/xen/drivers/passthrough/arm/ipmmu-vmsa.c b/xen/drivers/passthrough/arm/ipmmu-vmsa.c index e54b507..2a04800 100644 --- a/xen/drivers/passthrough/arm/ipmmu-vmsa.c +++ b/xen/drivers/passthrough/arm/ipmmu-vmsa.c @@ -708,8 +708,8 @@ static void ipmmu_tlb_flush_all(void *cookie) { struct ipmmu_vmsa_domain *domain = cookie; - /* Xen: Just return if context_id has non-existent value */ - if (domain->context_id >= domain->root->num_ctx) + /* Xen: Just return if context is absent or context_id has non-existent value */ + if (!domain || domain->context_id >= domain->root->num_ctx) return; ipmmu_tlb_invalidate(domain); @@ -796,7 +796,9 @@ static int ipmmu_domain_init_context(struct ipmmu_vmsa_domain *domain) */ ret = ipmmu_domain_allocate_context(domain->root, domain); if (ret < 0) { - free_io_pgtable_ops(domain->iop); + /* Pass root page table for this domain as an argument. */ + free_io_pgtable_ops(domain->iop, + maddr_to_page(domain->cfg.arm_lpae_s1_cfg.ttbr[0])); return ret; } @@ -2193,7 +2195,12 @@ static void ipmmu_vmsa_destroy_domain(struct iommu_domain *io_domain) * been detached. */ ipmmu_domain_destroy_context(domain); - free_io_pgtable_ops(domain->iop); + /* + * Pass root page table for this domain as an argument. + * This call will lead to start deallocation sequence. + */ + free_io_pgtable_ops(domain->iop, + maddr_to_page(domain->cfg.arm_lpae_s1_cfg.ttbr[0])); } kfree(domain); @@ -2383,6 +2390,17 @@ static int ipmmu_vmsa_domain_init(struct domain *d, bool use_iommu) return 0; } +/* + * Seems, there is one more page we need to process. So, retrieve + * the pointer and go on deallocation sequence. + */ +static void ipmmu_vmsa_free_page_table(struct page_info *page) +{ + struct io_pgtable_ops *ops = (struct io_pgtable_ops *)page->pad; + + free_io_pgtable_ops(ops, page); +} + static void __hwdom_init ipmmu_vmsa_hwdom_init(struct domain *d) { } @@ -2404,6 +2422,12 @@ static void ipmmu_vmsa_domain_teardown(struct domain *d) ASSERT(list_empty(&xen_domain->contexts)); xfree(xen_domain); dom_iommu(d)->arch.priv = NULL; + /* + * After this point we have all domain resources deallocated, except + * page table which we will deallocate asynchronously. The IOMMU code + * provides us with iommu_pt_cleanup_list and free_page_table platform + * callback what we actually going to use. + */ } static int __must_check ipmmu_vmsa_map_pages(struct domain *d, @@ -2462,6 +2486,7 @@ static void ipmmu_vmsa_dump_p2m_table(struct domain *d) static const struct iommu_ops ipmmu_vmsa_iommu_ops = { .init = ipmmu_vmsa_domain_init, .hwdom_init = ipmmu_vmsa_hwdom_init, + .free_page_table = ipmmu_vmsa_free_page_table, .teardown = ipmmu_vmsa_domain_teardown, .iotlb_flush = ipmmu_vmsa_iotlb_flush, .assign_device = ipmmu_vmsa_assign_dev, -- 2.7.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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