q35: implement TSEG

TSEG provides larger amounts of SMRAM than the 128 KB available with
legacy SMRAM and high SMRAM.

Route access to tseg into nowhere when enabled, for both cpus and
busmaster dma, and add tseg window to smram region, so cpus can access
it in smm mode.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

2 files changed, 71 insertions, 0 deletions

diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 305994bc38..bd7409456f 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -198,6 +198,28 @@ static const TypeInfo q35_host_info = {
  * MCH D0:F0
  */
 
+static uint64_t tseg_blackhole_read(void *ptr, hwaddr reg, unsigned size)
+{
+    return 0xffffffff;
+}
+
+static void tseg_blackhole_write(void *opaque, hwaddr addr, uint64_t val,
+                                 unsigned width)
+{
+    /* nothing */
+}
+
+static const MemoryRegionOps tseg_blackhole_ops = {
+    .read = tseg_blackhole_read,
+    .write = tseg_blackhole_write,
+    .endianness = DEVICE_NATIVE_ENDIAN,
+    .valid.min_access_size = 1,
+    .valid.max_access_size = 4,
+    .impl.min_access_size = 4,
+    .impl.max_access_size = 4,
+    .endianness = DEVICE_LITTLE_ENDIAN,
+};
+
 /* PCIe MMCFG */
 static void mch_update_pciexbar(MCHPCIState *mch)
 {
@@ -267,6 +289,7 @@ static void mch_update_smram(MCHPCIState *mch)
 {
     PCIDevice *pd = PCI_DEVICE(mch);
     bool h_smrame = (pd->config[MCH_HOST_BRIDGE_ESMRAMC] & MCH_HOST_BRIDGE_ESMRAMC_H_SMRAME);
+    uint32_t tseg_size;
 
     /* implement SMRAM.D_LCK */
     if (pd->config[MCH_HOST_BRIDGE_SMRAM] & MCH_HOST_BRIDGE_SMRAM_D_LCK) {
@@ -296,6 +319,39 @@ static void mch_update_smram(MCHPCIState *mch)
         memory_region_set_enabled(&mch->high_smram, false);
     }
 
+    if (pd->config[MCH_HOST_BRIDGE_ESMRAMC] & MCH_HOST_BRIDGE_ESMRAMC_T_EN) {
+        switch (pd->config[MCH_HOST_BRIDGE_ESMRAMC] &
+                MCH_HOST_BRIDGE_ESMRAMC_TSEG_SZ_MASK) {
+        case MCH_HOST_BRIDGE_ESMRAMC_TSEG_SZ_1MB:
+            tseg_size = 1024 * 1024;
+            break;
+        case MCH_HOST_BRIDGE_ESMRAMC_TSEG_SZ_2MB:
+            tseg_size = 1024 * 1024 * 2;
+            break;
+        case MCH_HOST_BRIDGE_ESMRAMC_TSEG_SZ_8MB:
+            tseg_size = 1024 * 1024 * 8;
+            break;
+        default:
+            tseg_size = 0;
+            break;
+        }
+    } else {
+        tseg_size = 0;
+    }
+    memory_region_del_subregion(mch->system_memory, &mch->tseg_blackhole);
+    memory_region_set_enabled(&mch->tseg_blackhole, tseg_size);
+    memory_region_set_size(&mch->tseg_blackhole, tseg_size);
+    memory_region_add_subregion_overlap(mch->system_memory,
+                                        mch->below_4g_mem_size - tseg_size,
+                                        &mch->tseg_blackhole, 1);
+
+    memory_region_set_enabled(&mch->tseg_window, tseg_size);
+    memory_region_set_size(&mch->tseg_window, tseg_size);
+    memory_region_set_address(&mch->tseg_window,
+                              mch->below_4g_mem_size - tseg_size);
+    memory_region_set_alias_offset(&mch->tseg_window,
+                                   mch->below_4g_mem_size - tseg_size);
+
     memory_region_transaction_commit();
 }
 
@@ -443,6 +499,20 @@ static void mch_realize(PCIDevice *d, Error **errp)
                              mch->ram_memory, 0xa0000, 0x20000);
     memory_region_set_enabled(&mch->high_smram, true);
     memory_region_add_subregion(&mch->smram, 0xfeda0000, &mch->high_smram);
+
+    memory_region_init_io(&mch->tseg_blackhole, OBJECT(mch),
+                          &tseg_blackhole_ops, NULL,
+                          "tseg-blackhole", 0);
+    memory_region_set_enabled(&mch->tseg_blackhole, false);
+    memory_region_add_subregion_overlap(mch->system_memory,
+                                        mch->below_4g_mem_size,
+                                        &mch->tseg_blackhole, 1);
+
+    memory_region_init_alias(&mch->tseg_window, OBJECT(mch), "tseg-window",
+                             mch->ram_memory, mch->below_4g_mem_size, 0);
+    memory_region_set_enabled(&mch->tseg_window, false);
+    memory_region_add_subregion(&mch->smram, mch->below_4g_mem_size,
+                                &mch->tseg_window);
     object_property_add_const_link(qdev_get_machine(), "smram",
                                    OBJECT(&mch->smram), &error_abort);
 
diff --git a/include/hw/pci-host/q35.h b/include/hw/pci-host/q35.h
index 113cbe8190..dbe6dc05b5 100644
--- a/include/hw/pci-host/q35.h
+++ b/include/hw/pci-host/q35.h
@@ -54,6 +54,7 @@ typedef struct MCHPCIState {
     PAMMemoryRegion pam_regions[13];
     MemoryRegion smram_region, open_high_smram;
     MemoryRegion smram, low_smram, high_smram;
+    MemoryRegion tseg_blackhole, tseg_window;
     PcPciInfo pci_info;
     ram_addr_t below_4g_mem_size;
     ram_addr_t above_4g_mem_size;