fw_cfg already supports exposure over MMIO (used in ppc/mac_newworld.c,
ppc/mac_oldworld.c, sparc/sun4m.c); we can easily add it to the "virt"
board.
Because MMIO access is slow on ARM KVM, we enable the guest, with
fw_cfg_init_data_memwidth(), to transfer up to 8 bytes with a single
access. This has been measured to speed up transfers up to 7.5-fold,
relative to single byte data access, on both ARM KVM and x86_64 TCG.
The mmio register block of fw_cfg is advertized in the device tree. As
base address we pick 0x09020000, which conforms to the comment preceding
"a15memmap": it falls in the miscellaneous device I/O range 128MB..256MB,
and it is aligned at 64KB. The DTB properties follow the documentation in
the Linux source file "Documentation/devicetree/bindings/arm/fw-cfg.txt".
fw_cfg automatically exports a number of files to the guest; for example,
"bootorder" (see fw_cfg_machine_reset()).
Signed-off-by: Laszlo Ersek <ler...@redhat.com>
---
Notes:
v3:
- enable 8-byte wide access to fw_cfg MMIO data port [Drew]
- expose the exact size of the fused region in the DTB [Peter]
- reorder data register and control register so that we can keep the
region contiguous and still conform to alignment requirements [Laszlo]
hw/arm/virt.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 314e55b..274aaae 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -67,8 +67,9 @@ enum {
VIRT_GIC_CPU,
VIRT_UART,
VIRT_MMIO,
VIRT_RTC,
+ VIRT_FW_CFG,
};
typedef struct MemMapEntry {
hwaddr base;
@@ -106,8 +107,9 @@ static const MemMapEntry a15memmap[] = {
[VIRT_GIC_DIST] = { 0x08000000, 0x00010000 },
[VIRT_GIC_CPU] = { 0x08010000, 0x00010000 },
[VIRT_UART] = { 0x09000000, 0x00001000 },
[VIRT_RTC] = { 0x09010000, 0x00001000 },
+ [VIRT_FW_CFG] = { 0x09020000, 0x0000000a },
[VIRT_MMIO] = { 0x0a000000, 0x00000200 },
/* ...repeating for a total of NUM_VIRTIO_TRANSPORTS, each of that size */
/* 0x10000000 .. 0x40000000 reserved for PCI */
[VIRT_MEM] = { 0x40000000, 30ULL * 1024 * 1024 * 1024 },
@@ -518,8 +520,25 @@ static void create_flash(const VirtBoardInfo *vbi)
qemu_fdt_setprop_cell(vbi->fdt, nodename, "bank-width", 4);
g_free(nodename);
}
+static void create_fw_cfg(const VirtBoardInfo *vbi)
+{
+ hwaddr base = vbi->memmap[VIRT_FW_CFG].base;
+ hwaddr size = vbi->memmap[VIRT_FW_CFG].size;
+ char *nodename;
+
+ fw_cfg_init_data_memwidth(0, 0, base + 8, base, 8);
+
+ nodename = g_strdup_printf("/fw-cfg@%" PRIx64, base);
+ qemu_fdt_add_subnode(vbi->fdt, nodename);
+ qemu_fdt_setprop_string(vbi->fdt, nodename,
+ "compatible", "qemu,fw-cfg-mmio");
+ qemu_fdt_setprop_sized_cells(vbi->fdt, nodename, "reg",
+ 2, base, 2, size);
+ g_free(nodename);
+}
+
static void *machvirt_dtb(const struct arm_boot_info *binfo, int *fdt_size)
{
const VirtBoardInfo *board = (const VirtBoardInfo *)binfo;
@@ -603,8 +622,10 @@ static void machvirt_init(MachineState *machine)
* no backend is created the transport will just sit harmlessly idle.
*/
create_virtio_devices(vbi, pic);
+ create_fw_cfg(vbi);
+
vbi->bootinfo.ram_size = machine->ram_size;
vbi->bootinfo.kernel_filename = machine->kernel_filename;
vbi->bootinfo.kernel_cmdline = machine->kernel_cmdline;
vbi->bootinfo.initrd_filename = machine->initrd_filename;
--
1.8.3.1
