[PATCH v2 10/10] iommu/ipmmu-vmsa: Support clearing mappings

Laurent Pinchart
2014-05-15T10:40:51Z

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
drivers/iommu/ipmmu-vmsa.c | 190 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 186 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/ipmmu-vmsa.c b/drivers/iommu/ipmmu-vmsa.c
index a4175d3..c003fae 100644
--- a/drivers/iommu/ipmmu-vmsa.c
+++ b/drivers/iommu/ipmmu-vmsa.c
@@ -192,14 +192,22 @@ static LIST_HEAD(ipmmu_devices);
#define ARM_VMSA_PTE_SH_NS (((pteval_t)0) << 8)
#define ARM_VMSA_PTE_SH_OS (((pteval_t)2) << 8)
#define ARM_VMSA_PTE_SH_IS (((pteval_t)3) << 8)
+#define ARM_VMSA_PTE_SH_MASK (((pteval_t)3) << 8)
#define ARM_VMSA_PTE_NS (((pteval_t)1) << 5)
#define ARM_VMSA_PTE_PAGE (((pteval_t)3) << 0)

/* Stage-1 PTE */
+#define ARM_VMSA_PTE_nG (((pteval_t)1) << 11)
#define ARM_VMSA_PTE_AP_UNPRIV (((pteval_t)1) << 6)
#define ARM_VMSA_PTE_AP_RDONLY (((pteval_t)2) << 6)
+#define ARM_VMSA_PTE_AP_MASK (((pteval_t)3) << 6)
+#define ARM_VMSA_PTE_ATTRINDX_MASK (((pteval_t)3) << 2)
#define ARM_VMSA_PTE_ATTRINDX_SHIFT 2
-#define ARM_VMSA_PTE_nG (((pteval_t)1) << 11)
+
+#define ARM_VMSA_PTE_ATTRS_MASK \
+ (ARM_VMSA_PTE_XN | ARM_VMSA_PTE_CONT | ARM_VMSA_PTE_nG | \
+ ARM_VMSA_PTE_AF | ARM_VMSA_PTE_SH_MASK | ARM_VMSA_PTE_AP_MASK | \
+ ARM_VMSA_PTE_NS | ARM_VMSA_PTE_ATTRINDX_MASK)

#define ARM_VMSA_PTE_CONT_ENTRIES 16
#define ARM_VMSA_PTE_CONT_SIZE (PAGE_SIZE * ARM_VMSA_PTE_CONT_ENTRIES)
@@ -614,7 +622,7 @@ static int ipmmu_alloc_init_pmd(struct ipmmu_vmsa_device *mmu, pmd_t *pmd,
return 0;
}

-static int ipmmu_handle_mapping(struct ipmmu_vmsa_domain *domain,
+static int ipmmu_create_mapping(struct ipmmu_vmsa_domain *domain,
unsigned long iova, phys_addr_t paddr,
size_t size, int prot)
{
@@ -668,6 +676,180 @@ done:
return ret;
}

+static void ipmmu_clear_pud(struct ipmmu_vmsa_device *mmu, pud_t *pud)
+{
+ /* Free the page table. */
+ pgtable_t table = pud_pgtable(*pud);
+ __free_page(table);
+
+ /* Clear the PUD. */
+ *pud = __pud(0);
+ ipmmu_flush_pgtable(mmu, pud, sizeof(*pud));
+}
+
+static void ipmmu_clear_pmd(struct ipmmu_vmsa_device *mmu, pud_t *pud,
+ pmd_t *pmd)
+{
+ unsigned int i;
+
+ /* Free the page table. */
+ if (pmd_table(*pmd)) {
+ pgtable_t table = pmd_pgtable(*pmd);
+ __free_page(table);
+ }
+
+ /* Clear the PMD. */
+ *pmd = __pmd(0);
+ ipmmu_flush_pgtable(mmu, pmd, sizeof(*pmd));
+
+ /* Check whether the PUD is still needed. */
+ pmd = pmd_offset(pud, 0);
+ for (i = 0; i < IPMMU_PTRS_PER_PMD; ++i) {
+ if (!pmd_none(pmd[i]))
+ return;
+ }
+
+ /* Clear the parent PUD. */
+ ipmmu_clear_pud(mmu, pud);
+}
+
+static void ipmmu_clear_pte(struct ipmmu_vmsa_device *mmu, pud_t *pud,
+ pmd_t *pmd, pte_t *pte, unsigned int num_ptes)
+{
+ unsigned int i;
+
+ /* Clear the PTE. */
+ for (i = num_ptes; i; --i)
+ pte[i-1] = __pte(0);
+
+ ipmmu_flush_pgtable(mmu, pte, sizeof(*pte) * num_ptes);
+
+ /* Check whether the PMD is still needed. */
+ pte = pte_offset_kernel(pmd, 0);
+ for (i = 0; i < IPMMU_PTRS_PER_PTE; ++i) {
+ if (!pte_none(pte[i]))
+ return;
+ }
+
+ /* Clear the parent PMD. */
+ ipmmu_clear_pmd(mmu, pud, pmd);
+}
+
+static int ipmmu_split_pmd(struct ipmmu_vmsa_device *mmu, pmd_t *pmd)
+{
+ pte_t *pte, *start;
+ pteval_t pteval;
+ unsigned long pfn;
+ unsigned int i;
+
+ pte = (pte_t *)get_zeroed_page(GFP_ATOMIC);
+ if (!pte)
+ return -ENOMEM;
+
+ /* Copy the PMD attributes. */
+ pteval = (pmd_val(*pmd) & ARM_VMSA_PTE_ATTRS_MASK)
+ | ARM_VMSA_PTE_CONT | ARM_VMSA_PTE_PAGE;
+
+ pfn = pmd_pfn(*pmd);
+ start = pte;
+
+ for (i = IPMMU_PTRS_PER_PTE; i; --i)
+ *pte++ = pfn_pte(pfn++, __pgprot(pteval));
+
+ ipmmu_flush_pgtable(mmu, start, PAGE_SIZE);
+ *pmd = __pmd(__pa(start) | PMD_NSTABLE | PMD_TYPE_TABLE);
+ ipmmu_flush_pgtable(mmu, pmd, sizeof(*pmd));
+
+ return 0;
+}
+
+static void ipmmu_split_pte(struct ipmmu_vmsa_device *mmu, pte_t *pte)
+{
+ unsigned int i;
+
+ for (i = ARM_VMSA_PTE_CONT_ENTRIES; i; --i)
+ pte[i-1] = __pte(pte_val(*pte) & ~ARM_VMSA_PTE_CONT);
+
+ ipmmu_flush_pgtable(mmu, pte, sizeof(*pte) * ARM_VMSA_PTE_CONT_ENTRIES);
+}
+
+static int ipmmu_clear_mapping(struct ipmmu_vmsa_domain *domain,
+ unsigned long iova, size_t size)
+{
+ struct ipmmu_vmsa_device *mmu = domain->mmu;
+ unsigned long flags;
+ pgd_t *pgd = domain->pgd;
+ pud_t *pud;
+ pmd_t *pmd;
+ pte_t *pte;
+ int ret = 0;
+
+ if (!pgd)
+ return -EINVAL;
+
+ if (size & ~PAGE_MASK)
+ return -EINVAL;
+
+ pgd += pgd_index(iova);
+ pud = (pud_t *)pgd;
+
+ spin_lock_irqsave(&domain->lock, flags);
+
+ /* If there's no PUD or PMD we're done. */
+ if (pud_none(*pud))
+ goto done;
+
+ pmd = pmd_offset(pud, iova);
+ if (pmd_none(*pmd))
+ goto done;
+
+ /*
+ * When freeing a 2MB block just clear the PMD. In the unlikely case the
+ * block is mapped as individual pages this will free the corresponding
+ * PTE page table.
+ */
+ if (size == SZ_2M) {
+ ipmmu_clear_pmd(mmu, pud, pmd);
+ goto done;
+ }
+
+ /*
+ * If the PMD has been mapped as a section remap it as pages to allow
+ * freeing individual pages.
+ */
+ if (pmd_sect(*pmd))
+ ipmmu_split_pmd(mmu, pmd);
+
+ pte = pte_offset_kernel(pmd, iova);
+
+ /*
+ * When freeing a 64kB block just clear the PTE entries. We don't have
+ * to care about the contiguous hint of the surrounding entries.
+ */
+ if (size == SZ_64K) {
+ ipmmu_clear_pte(mmu, pud, pmd, pte, ARM_VMSA_PTE_CONT_ENTRIES);
+ goto done;
+ }
+
+ /*
+ * If the PTE has been mapped with the contiguous hint set remap it and
+ * its surrounding PTEs to allow unmapping a single page.
+ */
+ if (pte_val(*pte) & ARM_VMSA_PTE_CONT)
+ ipmmu_split_pte(mmu, pte);
+
+ /* Clear the PTE. */
+ ipmmu_clear_pte(mmu, pud, pmd, pte, 1);
+
+done:
+ spin_unlock_irqrestore(&domain->lock, flags);
+
+ if (ret)
+ ipmmu_tlb_invalidate(domain);
+
+ return 0;
+}
+
/* -----------------------------------------------------------------------------
* IOMMU Operations
*/
@@ -768,7 +950,7 @@ static int ipmmu_map(struct iommu_domain *io_domain, unsigned long iova,
if (!domain)
return -ENODEV;

- return ipmmu_handle_mapping(domain, iova, paddr, size, prot);
+ return ipmmu_create_mapping(domain, iova, paddr, size, prot);
}

static size_t ipmmu_unmap(struct iommu_domain *io_domain, unsigned long iova,
@@ -777,7 +959,7 @@ static size_t ipmmu_unmap(struct iommu_domain *io_domain, unsigned long iova,
struct ipmmu_vmsa_domain *domain = io_domain->priv;
int ret;

- ret = ipmmu_handle_mapping(domain, iova, 0, size, 0);
+ ret = ipmmu_clear_mapping(domain, iova, size);
return ret ? 0 : size;
}

--
1.8.5.5