optionrom: add a DMA-enabled multiboot ROM
Add a new option rom for the multiboot loader, using DMA transfers to copy
data instead of "rep insb".
This significantly lowers QEMU's startup latency by a factor of about 40,
for example, going from 30sec to 0.8sec when loading modules of 120MB
in size.
Signed-off-by: Marcus Hähnel <marcus.haehnel@kernkonzept.com>
Signed-off-by: Adam Lackorzynski <adam@l4re.org>
[Modified to keep the non-DMA code depending on #ifdef USE_FW_CFG_DMA;
do not write below stack. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/pc-bios/meson.build b/pc-bios/meson.build
index a44c9bc..b40ff3f 100644
--- a/pc-bios/meson.build
+++ b/pc-bios/meson.build
@@ -63,6 +63,7 @@
'petalogix-s3adsp1800.dtb',
'petalogix-ml605.dtb',
'multiboot.bin',
+ 'multiboot_dma.bin',
'linuxboot.bin',
'linuxboot_dma.bin',
'kvmvapic.bin',
diff --git a/pc-bios/multiboot_dma.bin b/pc-bios/multiboot_dma.bin
new file mode 100644
index 0000000..c0e2c31
--- /dev/null
+++ b/pc-bios/multiboot_dma.bin
Binary files differ
diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
index 3482508..5d55d25 100644
--- a/pc-bios/optionrom/Makefile
+++ b/pc-bios/optionrom/Makefile
@@ -2,7 +2,7 @@
SRC_DIR := $(TOPSRC_DIR)/pc-bios/optionrom
VPATH = $(SRC_DIR)
-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin pvh.bin
+all: multiboot.bin multiboot_dma.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin pvh.bin
# Dummy command so that make thinks it has done something
@true
@@ -41,8 +41,6 @@
LD_I386_EMULATION ?= elf_i386
override LDFLAGS = -m $(LD_I386_EMULATION) -T $(SRC_DIR)/flat.lds
-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin pvh.bin
-
pvh.img: pvh.o pvh_main.o
%.o: %.S
diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S
index b7efe4d..181a4b0 100644
--- a/pc-bios/optionrom/multiboot.S
+++ b/pc-bios/optionrom/multiboot.S
@@ -68,7 +68,7 @@
mov %eax, %es
/* Read the bootinfo struct into RAM */
- read_fw_blob(FW_CFG_INITRD)
+ read_fw_blob_dma(FW_CFG_INITRD)
/* FS = bootinfo_struct */
read_fw FW_CFG_INITRD_ADDR
@@ -188,7 +188,7 @@
movl %eax, %gs
/* Read the kernel and modules into RAM */
- read_fw_blob(FW_CFG_KERNEL)
+ read_fw_blob_dma(FW_CFG_KERNEL)
/* Jump off to the kernel */
read_fw FW_CFG_KERNEL_ENTRY
diff --git a/pc-bios/optionrom/multiboot_dma.S b/pc-bios/optionrom/multiboot_dma.S
new file mode 100644
index 0000000..d809af3
--- /dev/null
+++ b/pc-bios/optionrom/multiboot_dma.S
@@ -0,0 +1,2 @@
+#define USE_FW_CFG_DMA 1
+#include "multiboot.S"
diff --git a/pc-bios/optionrom/optionrom.h b/pc-bios/optionrom/optionrom.h
index a2b612f..8d74c0d 100644
--- a/pc-bios/optionrom/optionrom.h
+++ b/pc-bios/optionrom/optionrom.h
@@ -37,6 +37,17 @@
#define BIOS_CFG_IOPORT_CFG 0x510
#define BIOS_CFG_IOPORT_DATA 0x511
+#define FW_CFG_DMA_CTL_ERROR 0x01
+#define FW_CFG_DMA_CTL_READ 0x02
+#define FW_CFG_DMA_CTL_SKIP 0x04
+#define FW_CFG_DMA_CTL_SELECT 0x08
+#define FW_CFG_DMA_CTL_WRITE 0x10
+
+#define FW_CFG_DMA_SIGNATURE 0x51454d5520434647ULL /* "QEMU CFG" */
+
+#define BIOS_CFG_DMA_ADDR_HIGH 0x514
+#define BIOS_CFG_DMA_ADDR_LOW 0x518
+
/* Break the translation block flow so -d cpu shows us values */
#define DEBUG_HERE \
jmp 1f; \
@@ -62,6 +73,61 @@
bswap %eax
.endm
+
+/*
+ * Read data from the fw_cfg device using DMA.
+ * Clobbers: %edx, %eax, ADDR, SIZE, memory[%esp-16] to memory[%esp]
+ */
+.macro read_fw_dma VAR, SIZE, ADDR
+ /* Address */
+ bswapl \ADDR
+ pushl \ADDR
+
+ /* We only support 32 bit target addresses */
+ xorl %eax, %eax
+ pushl %eax
+ mov $BIOS_CFG_DMA_ADDR_HIGH, %dx
+ outl %eax, (%dx)
+
+ /* Size */
+ bswapl \SIZE
+ pushl \SIZE
+
+ /* Control */
+ movl $(\VAR << 16) | (FW_CFG_DMA_CTL_READ | FW_CFG_DMA_CTL_SELECT), %eax
+ bswapl %eax
+ pushl %eax
+
+ movl %esp, %eax /* Address of the struct we generated */
+ bswapl %eax
+ mov $BIOS_CFG_DMA_ADDR_LOW, %dx
+ outl %eax, (%dx) /* Initiate DMA */
+
+1: mov (%esp), %eax /* Wait for completion */
+ bswapl %eax
+ testl $~FW_CFG_DMA_CTL_ERROR, %eax
+ jnz 1b
+ addl $16, %esp
+.endm
+
+
+/*
+ * Read a blob from the fw_cfg device using DMA
+ * Requires _ADDR, _SIZE and _DATA values for the parameter.
+ *
+ * Clobbers: %eax, %edx, %es, %ecx, %edi and adresses %esp-20 to %esp
+ */
+#ifdef USE_FW_CFG_DMA
+#define read_fw_blob_dma(var) \
+ read_fw var ## _SIZE; \
+ mov %eax, %ecx; \
+ read_fw var ## _ADDR; \
+ mov %eax, %edi ;\
+ read_fw_dma var ## _DATA, %ecx, %edi
+#else
+#define read_fw_blob_dma(var) read_fw_blob(var)
+#endif
+
#define read_fw_blob_pre(var) \
read_fw var ## _SIZE; \
mov %eax, %ecx; \
