From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

Introduce 'nodma' shared memory region to support PT mode
so that for each device, we only create an alias to shared memory
region when DMA-remapping is disabled.

Reviewed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Santosh Shukla <santosh.shukla@amd.com>
Message-Id: <20240927172913.121477-3-santosh.shukla@amd.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/i386/amd_iommu.h |  2 ++
 hw/i386/amd_iommu.c | 49 ++++++++++++++++++++++++++++++++++++---------
 2 files changed, 42 insertions(+), 9 deletions(-)

diff --git a/hw/i386/amd_iommu.h b/hw/i386/amd_iommu.h
index e5c2ae94f2..be417e51c4 100644
--- a/hw/i386/amd_iommu.h
+++ b/hw/i386/amd_iommu.h
@@ -354,6 +354,8 @@ struct AMDVIState {
     uint32_t pprlog_tail;        /* ppr log tail */
 
     MemoryRegion mr_mmio;              /* MMIO region                  */
+    MemoryRegion mr_sys;
+    MemoryRegion mr_nodma;
     uint8_t mmior[AMDVI_MMIO_SIZE];    /* read/write MMIO              */
     uint8_t w1cmask[AMDVI_MMIO_SIZE];  /* read/write 1 clear mask      */
     uint8_t romask[AMDVI_MMIO_SIZE];   /* MMIO read/only mask          */
diff --git a/hw/i386/amd_iommu.c b/hw/i386/amd_iommu.c
index abb64ea507..7c7760c573 100644
--- a/hw/i386/amd_iommu.c
+++ b/hw/i386/amd_iommu.c
@@ -60,8 +60,9 @@ struct AMDVIAddressSpace {
     uint8_t bus_num;            /* bus number                           */
     uint8_t devfn;              /* device function                      */
     AMDVIState *iommu_state;    /* AMDVI - one per machine              */
-    MemoryRegion root;          /* AMDVI Root memory map region */
+    MemoryRegion root;          /* AMDVI Root memory map region         */
     IOMMUMemoryRegion iommu;    /* Device's address translation region  */
+    MemoryRegion iommu_nodma;   /* Alias of shared nodma memory region  */
     MemoryRegion iommu_ir;      /* Device's interrupt remapping region  */
     AddressSpace as;            /* device's corresponding address space */
 };
@@ -1412,6 +1413,7 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
     AMDVIState *s = opaque;
     AMDVIAddressSpace **iommu_as, *amdvi_dev_as;
     int bus_num = pci_bus_num(bus);
+    X86IOMMUState *x86_iommu = X86_IOMMU_DEVICE(s);
 
     iommu_as = s->address_spaces[bus_num];
 
@@ -1436,13 +1438,13 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
          * Memory region relationships looks like (Address range shows
          * only lower 32 bits to make it short in length...):
          *
-         * |-----------------+-------------------+----------|
-         * | Name            | Address range     | Priority |
-         * |-----------------+-------------------+----------+
-         * | amdvi_root      | 00000000-ffffffff |        0 |
-         * |  amdvi_iommu    | 00000000-ffffffff |        1 |
-         * |  amdvi_iommu_ir | fee00000-feefffff |       64 |
-         * |-----------------+-------------------+----------|
+         * |--------------------+-------------------+----------|
+         * | Name               | Address range     | Priority |
+         * |--------------------+-------------------+----------+
+         * | amdvi-root         | 00000000-ffffffff |        0 |
+         * |  amdvi-iommu_nodma  | 00000000-ffffffff |       0 |
+         * |  amdvi-iommu_ir     | fee00000-feefffff |      64 |
+         * |--------------------+-------------------+----------|
          */
         memory_region_init_iommu(&amdvi_dev_as->iommu,
                                  sizeof(amdvi_dev_as->iommu),
@@ -1461,7 +1463,25 @@ static AddressSpace *amdvi_host_dma_iommu(PCIBus *bus, void *opaque, int devfn)
                                             64);
         memory_region_add_subregion_overlap(&amdvi_dev_as->root, 0,
                                             MEMORY_REGION(&amdvi_dev_as->iommu),
-                                            1);
+                                            0);
+
+        /* Build the DMA Disabled alias to shared memory */
+        memory_region_init_alias(&amdvi_dev_as->iommu_nodma, OBJECT(s),
+                                 "amdvi-sys", &s->mr_sys, 0,
+                                 memory_region_size(&s->mr_sys));
+        memory_region_add_subregion_overlap(&amdvi_dev_as->root, 0,
+                                            &amdvi_dev_as->iommu_nodma,
+                                            0);
+
+        if (!x86_iommu->pt_supported) {
+            memory_region_set_enabled(&amdvi_dev_as->iommu_nodma, false);
+            memory_region_set_enabled(MEMORY_REGION(&amdvi_dev_as->iommu),
+                                      true);
+        } else {
+            memory_region_set_enabled(MEMORY_REGION(&amdvi_dev_as->iommu),
+                                      false);
+            memory_region_set_enabled(&amdvi_dev_as->iommu_nodma, true);
+        }
     }
     return &iommu_as[devfn]->as;
 }
@@ -1602,6 +1622,17 @@ static void amdvi_sysbus_realize(DeviceState *dev, Error **errp)
                           "amdvi-mmio", AMDVI_MMIO_SIZE);
     memory_region_add_subregion(get_system_memory(), AMDVI_BASE_ADDR,
                                 &s->mr_mmio);
+
+    /* Create the share memory regions by all devices */
+    memory_region_init(&s->mr_sys, OBJECT(s), "amdvi-sys", UINT64_MAX);
+
+    /* set up the DMA disabled memory region */
+    memory_region_init_alias(&s->mr_nodma, OBJECT(s),
+                             "amdvi-nodma", get_system_memory(), 0,
+                             memory_region_size(get_system_memory()));
+    memory_region_add_subregion_overlap(&s->mr_sys, 0,
+                                        &s->mr_nodma, 0);
+
     pci_setup_iommu(bus, &amdvi_iommu_ops, s);
     amdvi_init(s);
 }
-- 
MST