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 PnNE3+gk Z0pA66wuwLdkVx2yYDlahX9yDvnAIyEzJMfy8smmn3awrCpvR0JIc36w64NMeFvYx63UY6IhEZsExcFcdxYeOhQumqt4ZRYGgUxf+noptTAhpEyIitXMb0uTrg2OFrgjj3opqrRYn69DyedaArwR1D9rpsEueTwhOhVk1SgSpXVU+c67XyCeFERiDoyDzo4J8n28i662lHnVsbS2+OMVxn6XvqOQNFSXUy5hSYM/ttE/MMiEM0bGqmxil3dtHmYbo8wAVGLN8c25KY3qkxmucSlD2FpRYEfH8TRFV8lxKUcjH6ZssBi3SKIgsLDiVbZ/nuOsRFnmsIEOfaF5QS5BavCLzgbcjjh8UOQmF34u6EU9fWaoWxwnDUxTzbf4/Vk6SVj4+CVTQnAdw9am/CH+LlANFwITi1Pm+01li X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/21/2023 11:19 AM, Pasha Tatashin wrote: > In order to be able to efficiently free empty page table levels, count the > number of entries in each page table my incremeanting and decremeanting s/incremeanting/incrementing s/decremeanting/decrementing > refcount every time a PTE is inserted or removed form the page table. s/form/from > > For this to work correctly, add two helper function: > dma_clear_pte and dma_set_pte where counting is performed, > > Also, modify the code so every page table entry is always updated using the > two new functions. > > Signed-off-by: Pasha Tatashin > --- > drivers/iommu/intel/iommu.c | 40 +++++++++++++++++++++--------------- > drivers/iommu/intel/iommu.h | 41 +++++++++++++++++++++++++++++++------ > 2 files changed, 58 insertions(+), 23 deletions(-) > > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c > index 897159dba47d..4688ef797161 100644 > --- a/drivers/iommu/intel/iommu.c > +++ b/drivers/iommu/intel/iommu.c > @@ -949,7 +949,7 @@ static struct dma_pte *pfn_to_dma_pte(struct dmar_domain *domain, > if (domain->use_first_level) > pteval |= DMA_FL_PTE_XD | DMA_FL_PTE_US | DMA_FL_PTE_ACCESS; > > - if (cmpxchg64(&pte->val, 0ULL, pteval)) > + if (dma_set_pte(pte, pteval)) > /* Someone else set it while we were thinking; use theirs. */ > free_pgtable_page(tmp_page); > else > @@ -1021,7 +1021,8 @@ static void dma_pte_clear_range(struct dmar_domain *domain, > continue; > } > do { > - dma_clear_pte(pte); > + if (dma_pte_present(pte)) > + dma_clear_pte(pte); > start_pfn += lvl_to_nr_pages(large_page); > pte++; > } while (start_pfn <= last_pfn && !first_pte_in_page(pte)); > @@ -1062,7 +1063,8 @@ static void dma_pte_free_level(struct dmar_domain *domain, int level, > */ > if (level < retain_level && !(start_pfn > level_pfn || > last_pfn < level_pfn + level_size(level) - 1)) { > - dma_clear_pte(pte); > + if (dma_pte_present(pte)) > + dma_clear_pte(pte); > domain_flush_cache(domain, pte, sizeof(*pte)); > free_pgtable_page(level_pte); > } > @@ -1093,12 +1095,13 @@ static void dma_pte_free_pagetable(struct dmar_domain *domain, > } > } > > -/* When a page at a given level is being unlinked from its parent, we don't > - need to *modify* it at all. All we need to do is make a list of all the > - pages which can be freed just as soon as we've flushed the IOTLB and we > - know the hardware page-walk will no longer touch them. > - The 'pte' argument is the *parent* PTE, pointing to the page that is to > - be freed. */ > +/* > + * A given page at a given level is being unlinked from its parent. > + * We need to make a list of all the pages which can be freed just as soon as > + * we've flushed the IOTLB and we know the hardware page-walk will no longer > + * touch them. The 'pte' argument is the *parent* PTE, pointing to the page > + * that is to be freed. > + */ > static void dma_pte_list_pagetables(struct dmar_domain *domain, > int level, struct dma_pte *pte, > struct list_head *freelist) > @@ -1106,17 +1109,20 @@ static void dma_pte_list_pagetables(struct dmar_domain *domain, > struct page *pg; > > pg = pfn_to_page(dma_pte_addr(pte) >> PAGE_SHIFT); > - list_add_tail(&pg->lru, freelist); > - > - if (level == 1) > - return; > - > pte = page_address(pg); > + > do { > - if (dma_pte_present(pte) && !dma_pte_superpage(pte)) > - dma_pte_list_pagetables(domain, level - 1, pte, freelist); > + if (dma_pte_present(pte)) { > + if (level > 1 && !dma_pte_superpage(pte)) { > + dma_pte_list_pagetables(domain, level - 1, pte, > + freelist); > + } > + dma_clear_pte(pte); > + } > pte++; > } while (!first_pte_in_page(pte)); > + > + list_add_tail(&pg->lru, freelist); > } > How about calculating the page decrement when the pages in the freelist are really freed in iommu_free_pgtbl_pages() ? Thanks, Jingqi