[Xen-devel] [PATCH 7/7] amd-iommu: add lookup_page method to iommu_ops

[Paul Durrant <paul.durrant@xxxxxxxxxx>]

This patch adds a new method to the AMD IOMMU implementation to find the
MFN currently mapped by the specified DFN. This is analogous to the
method added for VT-d IOMMU by commit 43d1622b.

Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Cc: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
Cc: Brian Woods <brian.woods@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 xen/drivers/passthrough/amd/iommu_map.c       | 50 +++++++++++++++++++++++++++
 xen/drivers/passthrough/amd/pci_amd_iommu.c   |  1 +
 xen/include/asm-x86/hvm/svm/amd-iommu-proto.h |  2 ++
 3 files changed, 53 insertions(+)

diff --git a/xen/drivers/passthrough/amd/iommu_map.c 
b/xen/drivers/passthrough/amd/iommu_map.c
index fecde9d645..309720743f 100644
--- a/xen/drivers/passthrough/amd/iommu_map.c
+++ b/xen/drivers/passthrough/amd/iommu_map.c
@@ -69,6 +69,20 @@ static void get_iommu_pde_info(uint32_t *pde, uint64_t 
*maddr, bool *iw,
                                        IOMMU_PDE_IO_READ_PERMISSION_SHIFT);
 }
 
+static void get_iommu_pte_info(unsigned long l1_mfn, unsigned long dfn,
+                               uint64_t *maddr, bool *iw, bool *ir)
+{
+    uint64_t *table;
+    uint32_t *pde;
+
+    table = map_domain_page(_mfn(l1_mfn));
+    pde = (uint32_t *)(table + pfn_to_pde_idx(dfn,
+                                              IOMMU_PAGING_MODE_LEVEL_1));
+
+    get_iommu_pde_info(pde, maddr, iw, ir);
+    unmap_domain_page(table);
+}
+
 static bool set_iommu_pde_info(uint32_t *pde, uint64_t maddr, bool iw,
                                bool ir)
 {
@@ -793,6 +807,42 @@ int amd_iommu_unmap_page(struct domain *d, dfn_t dfn)
     return 0;
 }
 
+int amd_iommu_lookup_page(struct domain *d, dfn_t dfn, mfn_t *mfn,
+                          unsigned int *flags)
+{
+    unsigned long pt_mfn[7] = {};
+    struct domain_iommu *hd = dom_iommu(d);
+    uint64_t maddr;
+    bool iw, ir;
+    int rc;
+
+    if ( iommu_use_hap_pt(d) )
+        return -EOPNOTSUPP;
+
+    spin_lock(&hd->arch.mapping_lock);
+
+    if ( !hd->arch.root_table )
+    {
+        spin_unlock(&hd->arch.mapping_lock);
+        return -EOPNOTSUPP;
+    }
+
+    rc = iommu_pde_from_dfn(d, dfn_x(dfn), pt_mfn);
+    if ( rc )
+    {
+        spin_unlock(&hd->arch.mapping_lock);
+        return rc;
+    }
+
+    get_iommu_pte_info(pt_mfn[1], dfn_x(dfn), &maddr, &iw, &ir);
+    spin_unlock(&hd->arch.mapping_lock);
+
+    *mfn = _mfn(maddr >> PAGE_SHIFT);
+    *flags = (iw ? IOMMUF_writable : 0) | (ir ? IOMMUF_readable : 0);
+
+    return 0;
+}
+
 int amd_iommu_reserve_domain_unity_map(struct domain *domain,
                                        uint64_t phys_addr,
                                        unsigned long size, int iw, int ir)
diff --git a/xen/drivers/passthrough/amd/pci_amd_iommu.c 
b/xen/drivers/passthrough/amd/pci_amd_iommu.c
index 5e99b6988e..86b97d7eaf 100644
--- a/xen/drivers/passthrough/amd/pci_amd_iommu.c
+++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c
@@ -616,6 +616,7 @@ const struct iommu_ops amd_iommu_ops = {
     .teardown = amd_iommu_domain_destroy,
     .map_page = amd_iommu_map_page,
     .unmap_page = amd_iommu_unmap_page,
+    .lookup_page = amd_iommu_lookup_page,
     .free_page_table = deallocate_page_table,
     .reassign_device = reassign_device,
     .get_device_group_id = amd_iommu_group_id,
diff --git a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h 
b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
index 3083d625bd..d451acc28c 100644
--- a/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
+++ b/xen/include/asm-x86/hvm/svm/amd-iommu-proto.h
@@ -55,6 +55,8 @@ int amd_iommu_update_ivrs_mapping_acpi(void);
 int __must_check amd_iommu_map_page(struct domain *d, dfn_t dfn,
                                     mfn_t mfn, unsigned int flags);
 int __must_check amd_iommu_unmap_page(struct domain *d, dfn_t dfn);
+int __must_check amd_iommu_lookup_page(struct domain *d, dfn_t dfn,
+                                       mfn_t *mfn, unsigned int *flags);
 u64 amd_iommu_get_next_table_from_pte(u32 *entry);
 int __must_check amd_iommu_alloc_root(struct domain_iommu *hd);
 int amd_iommu_reserve_domain_unity_map(struct domain *domain,
-- 
2.11.0


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