[Qemu-devel] [PATCH 2/2 v4] pc: add 'etc/reserved-memory-end' fw_cfg interface for SeaBIOS

[Igor Mammedov]

'etc/reserved-memory-end' will allow QEMU to tell BIOS where PCI
BARs mapping could safely start in high memory.

Allowing BIOS to start mapping 64-bit PCI BARs at address where it
wouldn't conflict with other mappings QEMU might place before it.

That permits QEMU to reserve extra address space before
64-bit PCI hole for memory hotplug.

Signed-off-by: Igor Mammedov <address@hidden>
---
v2:
   * disable 'etc/reserved-memory-end' for 1.7 and older machine types
---
 hw/i386/pc.c         | 27 +++++++++++++++++++++++++--
 hw/i386/pc_piix.c    |  1 +
 hw/i386/pc_q35.c     |  1 +
 hw/pci-host/piix.c   |  3 ++-
 hw/pci-host/q35.c    |  3 ++-
 include/hw/i386/pc.h | 11 +++++++++--
 6 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 6c82ada..ba82c67 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1094,14 +1094,37 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t 
below_4g_mem_size,
 }
 
 /* setup pci memory address space mapping into system address space */
-void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
-                            MemoryRegion *pci_address_space)
+void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
+                                MemoryRegion *pci_address_space,
+                                uint64_t reserved_memory_end)
 {
     /* Set to lower priority than RAM */
     memory_region_add_subregion_overlap(system_memory, 0x0,
                                         pci_address_space, -1);
 }
 
+static
+void pc_pci_as_mapping_init_1_8(Object *owner, MemoryRegion *system_memory,
+                                MemoryRegion *pci_address_space,
+                                uint64_t reserved_memory_end)
+{
+    uint64_t *val;
+    FWCfgState *fw_cfg = fw_cfg_find();
+    g_assert(fw_cfg);
+    /*
+     *  Align address at 1G, this makes sure it can be exactly covered
+     *  with a PAT entry even when using huge pages.
+     */
+    val = g_malloc(sizeof(*val));
+    *val = cpu_to_le64(ROUND_UP(reserved_memory_end, 0x1ULL << 30));
+    fw_cfg_add_file(fw_cfg, "etc/reserved-memory-end", val, sizeof(*val));
+
+    pc_pci_as_mapping_init_1_7(owner, system_memory, pci_address_space,
+                               reserved_memory_end);
+}
+
+pc_pci_as_mapping_init_fn pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_8;
+
 void pc_acpi_init(const char *default_dsdt)
 {
     char *filename;
diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
index 0456ab1..c0904f9 100644
--- a/hw/i386/pc_piix.c
+++ b/hw/i386/pc_piix.c
@@ -240,6 +240,7 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
 
 static void pc_compat_1_7(QEMUMachineInitArgs *args)
 {
+    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
 }
 
 static void pc_compat_1_6(QEMUMachineInitArgs *args)
diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
index b18e966..c165843 100644
--- a/hw/i386/pc_q35.c
+++ b/hw/i386/pc_q35.c
@@ -224,6 +224,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
 
 static void pc_compat_1_7(QEMUMachineInitArgs *args)
 {
+    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
 }
 
 static void pc_compat_1_6(QEMUMachineInitArgs *args)
diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index 5d4e290..16205e7 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -351,7 +351,8 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
 
     /* setup pci memory mapping */
     pc_pci_as_mapping_init(OBJECT(f), f->system_memory,
-                           f->pci_address_space);
+                           f->pci_address_space,
+                           0x100000000ULL + above_4g_mem_size);
 
     memory_region_init_alias(&f->smram_region, OBJECT(d), "smram-region",
                              f->pci_address_space, 0xa0000, 0x20000);
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index d1792de..1293353 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -353,7 +353,8 @@ static int mch_init(PCIDevice *d)
 
     /* setup pci memory mapping */
     pc_pci_as_mapping_init(OBJECT(mch), mch->system_memory,
-                           mch->pci_address_space);
+                           mch->pci_address_space,
+                           0x100000000ULL + mch->above_4g_mem_size);
 
     /* smram */
     cpu_smm_register(&mch_set_smm, mch);
diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
index 8b3be3c..bf1b168 100644
--- a/include/hw/i386/pc.h
+++ b/include/hw/i386/pc.h
@@ -129,8 +129,15 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t 
below_4g_mem_size,
 #define DEFAULT_PCI_HOLE64_SIZE (~0x0ULL)
 
 
-void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
-                            MemoryRegion *pci_address_space);
+typedef
+void (*pc_pci_as_mapping_init_fn)(Object *owner, MemoryRegion *system_memory,
+                                  MemoryRegion *pci_address_space,
+                                  uint64_t reserved_memory_end);
+extern pc_pci_as_mapping_init_fn pc_pci_as_mapping_init;
+
+void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
+                                MemoryRegion *pci_address_space,
+                                uint64_t reserved_memory_end);
 
 FWCfgState *pc_memory_init(MemoryRegion *system_memory,
                            const char *kernel_filename,
-- 
1.8.3.1