From: Marcus Hähnel <marcus.haeh...@kernkonzept.com> 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.haeh...@kernkonzept.com> Signed-off-by: Adam Lackorzynski <a...@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 <pbonz...@redhat.com> --- pc-bios/meson.build | 1 + pc-bios/multiboot_dma.bin | Bin 0 -> 1024 bytes pc-bios/optionrom/Makefile | 4 +- pc-bios/optionrom/multiboot.S | 4 +- pc-bios/optionrom/multiboot_dma.S | 2 + pc-bios/optionrom/optionrom.h | 66 ++++++++++++++++++++++++++++++ 6 files changed, 72 insertions(+), 5 deletions(-) create mode 100644 pc-bios/multiboot_dma.bin create mode 100644 pc-bios/optionrom/multiboot_dma.S diff --git a/pc-bios/meson.build b/pc-bios/meson.build index a44c9bc127..b40ff3f2bd 100644 --- a/pc-bios/meson.build +++ b/pc-bios/meson.build @@ -63,6 +63,7 @@ blobs = files( '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 0000000000000000000000000000000000000000..c0e2c3102a3358207c61d3ae113524fb6007abc3 GIT binary patch literal 1024 zcmd^-v1=1i9LIlmUTlcNU1}{N5`u&{DAHSmq6iKdix;GHRxaNnR0A<Lc978Fk#IvN zaS+5wQE+fL&*iQWa#czc94ZyL>R{3q;@~8~^LMo;4s!p158nI!-tWur_ul*P<{!&% z=%3>xm5f`4Bq!!)`Rkwf;(oFd*qcAb=mhXX1)X>Bw-tylkUpR_ETXkH1AnO4L$nJ| zWJui_M1kmKmTID)P`mI^=HM`~{VB1t1l_Ye=Lor4X5{8Gd)zzw_o4<6zLQJ!dr<pW z;7%~ysSHL?*HHx*O%k}?fCyRL<7_RWt(4;Aqn}X}S>MolrKNZG2Z|kTOyaJIhYFc^ zFhhuQ9`r5fQLCrm#T4^_QylQ>8kgs;ZX9bIEiXb`8AIxu;?h~d%9izBkKht%WM1G* z^E{W9(OT9dt5in2qF}|dPH>dL>{=sV#-U1<quUb@YkIW%niI?8-7fCz#695e<V=WZ zrVCY?W~`3Hw@^=cHALr#9F2GOTYJ;??9d*-Vbsi+;lz|<$jMX#;lr6ov3qKNLH7(W z+>yFoWnOtw14D$&k*SUtsT%wS`ki@#&rUrnmtuDv`PtJm(Kg?H$Pdc0CL@YCy4R<D pT|LnIbg(BnP0#tqRx5M!bkkaD-nd?`H;YU4Yi6yHwD{k({tHC8FAx9# literal 0 HcmV?d00001 diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile index 3482508a86..5d55d25acc 100644 --- a/pc-bios/optionrom/Makefile +++ b/pc-bios/optionrom/Makefile @@ -2,7 +2,7 @@ include config.mak 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 @@ override CFLAGS += $(call cc-option, $(Wa)-32) 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 b7efe4de34..181a4b03a3 100644 --- a/pc-bios/optionrom/multiboot.S +++ b/pc-bios/optionrom/multiboot.S @@ -68,7 +68,7 @@ run_multiboot: 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 @@ prot_mode: 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 0000000000..d809af3e23 --- /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 a2b612f1a7..8d74c0ddf3 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; \ -- 2.31.1