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author | Marcus Hähnel <marcus.haehnel@kernkonzept.com> | 2021-10-20 14:55:04 +0200 |
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committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-11-02 15:57:27 +0100 |
commit | 48972f8cad24eb4462c97ea68003e2dd35be0444 (patch) | |
tree | 6381678103fc9d67e5247006b31c218828a39eda /pc-bios/optionrom/optionrom.h | |
parent | f014c974595a1e3482c6afb57557a6e479b80328 (diff) | |
download | qemu-48972f8cad24eb4462c97ea68003e2dd35be0444.zip qemu-48972f8cad24eb4462c97ea68003e2dd35be0444.tar.gz qemu-48972f8cad24eb4462c97ea68003e2dd35be0444.tar.bz2 |
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>
Diffstat (limited to 'pc-bios/optionrom/optionrom.h')
-rw-r--r-- | pc-bios/optionrom/optionrom.h | 66 |
1 files changed, 66 insertions, 0 deletions
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; \ |