[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] AMD/IOMMU: free all-empty page tables
commit 2d1bb66d87c2bec712643593584821d056e3b97e Author: Jan Beulich <jbeulich@xxxxxxxx> AuthorDate: Mon Jul 25 15:40:00 2022 +0200 Commit: Jan Beulich <jbeulich@xxxxxxxx> CommitDate: Mon Jul 25 15:40:00 2022 +0200 AMD/IOMMU: free all-empty page tables When a page table ends up with no present entries left, it can be replaced by a non-present entry at the next higher level. The page table itself can then be scheduled for freeing. Note that while its output isn't used there yet, pt_update_contig_markers() right away needs to be called in all places where entries get updated, not just the one where entries get cleared. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx> Reviewed-by: Paul Durrant <paul@xxxxxxx> --- xen/drivers/passthrough/amd/iommu_map.c | 37 ++++++++++++++++++++++++++++++--- 1 file changed, 34 insertions(+), 3 deletions(-) diff --git a/xen/drivers/passthrough/amd/iommu_map.c b/xen/drivers/passthrough/amd/iommu_map.c index 7d4e0ba587..a50a6b79ab 100644 --- a/xen/drivers/passthrough/amd/iommu_map.c +++ b/xen/drivers/passthrough/amd/iommu_map.c @@ -21,6 +21,7 @@ #include "iommu.h" +#define CONTIG_MASK IOMMU_PTE_CONTIG_MASK #include <asm/pt-contig-markers.h> /* Given pfn and page table level, return pde index */ @@ -35,16 +36,20 @@ static unsigned int pfn_to_pde_idx(unsigned long pfn, unsigned int level) static union amd_iommu_pte clear_iommu_pte_present(unsigned long l1_mfn, unsigned long dfn, - unsigned int level) + unsigned int level, + bool *free) { union amd_iommu_pte *table, *pte, old; + unsigned int idx = pfn_to_pde_idx(dfn, level); table = map_domain_page(_mfn(l1_mfn)); - pte = &table[pfn_to_pde_idx(dfn, level)]; + pte = &table[idx]; old = *pte; write_atomic(&pte->raw, 0); + *free = pt_update_contig_markers(&table->raw, idx, level, PTE_kind_null); + unmap_domain_page(table); return old; @@ -87,7 +92,11 @@ static union amd_iommu_pte set_iommu_pte_present(unsigned long pt_mfn, if ( !old.pr || old.next_level || old.mfn != next_mfn || old.iw != iw || old.ir != ir ) + { set_iommu_pde_present(pde, next_mfn, 0, iw, ir); + pt_update_contig_markers(&table->raw, pfn_to_pde_idx(dfn, level), + level, PTE_kind_leaf); + } else old.pr = false; /* signal "no change" to the caller */ @@ -326,6 +335,9 @@ static int iommu_pde_from_dfn(struct domain *d, unsigned long dfn, smp_wmb(); set_iommu_pde_present(pde, next_table_mfn, next_level, true, true); + pt_update_contig_markers(&next_table_vaddr->raw, + pfn_to_pde_idx(dfn, level), + level, PTE_kind_table); *flush_flags |= IOMMU_FLUSHF_modified; } @@ -351,6 +363,9 @@ static int iommu_pde_from_dfn(struct domain *d, unsigned long dfn, next_table_mfn = mfn_x(page_to_mfn(table)); set_iommu_pde_present(pde, next_table_mfn, next_level, true, true); + pt_update_contig_markers(&next_table_vaddr->raw, + pfn_to_pde_idx(dfn, level), + level, PTE_kind_table); } else /* should never reach here */ { @@ -487,8 +502,24 @@ int cf_check amd_iommu_unmap_page( if ( pt_mfn ) { + bool free; + /* Mark PTE as 'page not present'. */ - old = clear_iommu_pte_present(pt_mfn, dfn_x(dfn), level); + old = clear_iommu_pte_present(pt_mfn, dfn_x(dfn), level, &free); + + while ( unlikely(free) && ++level < hd->arch.amd.paging_mode ) + { + struct page_info *pg = mfn_to_page(_mfn(pt_mfn)); + + if ( iommu_pde_from_dfn(d, dfn_x(dfn), level, &pt_mfn, + flush_flags, false) ) + BUG(); + BUG_ON(!pt_mfn); + + clear_iommu_pte_present(pt_mfn, dfn_x(dfn), level, &free); + *flush_flags |= IOMMU_FLUSHF_all; + iommu_queue_free_pgtable(hd, pg); + } } spin_unlock(&hd->arch.mapping_lock); -- generated by git-patchbot for /home/xen/git/xen.git#staging
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