>From cd167170239d60c8d13c56c881ee5f31387857af Mon Sep 17 00:00:00 2001
From: Richard Jones <address@hidden>
Date: Sat, 17 Jul 2010 14:30:46 +0100
Subject: [PATCH 2/2] fw_cfg: Add blit operation for copying kernel, initrd, setup, cmdline.

This adds a "blit" operation for rapidly copying the kernel, initrd
etc into the guest.  Instead of doing an "inb" operation for every
byte of these images, the guest sets up a blit address and issues
a special read_fw with the FW_CFG_BLIT bit set.  This instructs
qemu to copy the whole of the image to the blit address.

With this patch, loading large initrds is several seconds faster,
and overall boot time is reduced correspondingly.

Signed-off-by: Richard W.M. Jones <address@hidden>
---
 hw/fw_cfg.c                   |   19 ++++++++++++++++++-
 hw/fw_cfg.h                   |    7 +++++--
 pc-bios/optionrom/linuxboot.S |    8 ++++----
 pc-bios/optionrom/optionrom.h |   37 +++++++++++++++++++++++++++++++++++++
 4 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/hw/fw_cfg.c b/hw/fw_cfg.c
index 37e6f1f..12206ea 100644
--- a/hw/fw_cfg.c
+++ b/hw/fw_cfg.c
@@ -55,6 +55,11 @@ struct FWCfgState {
     uint32_t cur_offset;
 };
 
+/* Target address for blit operations.  Only writes to lower 4GB
+ * addresses are supported .
+ */
+static uint32_t blitaddr = 0;
+
 static void fw_cfg_write(FWCfgState *s, uint8_t value)
 {
     int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
@@ -98,7 +103,17 @@ static uint8_t fw_cfg_read(FWCfgState *s)
 
     if (s->cur_entry == FW_CFG_INVALID || !e->data || s->cur_offset >= e->len)
         ret = 0;
-    else
+    else if (s->cur_entry & FW_CFG_BLIT) {
+        if (blitaddr == 0)
+            ret = 0; /* guest must set up a blit address beforehand */
+        else {
+            cpu_physical_memory_write ((target_phys_addr_t) blitaddr,
+                                       &e->data[s->cur_offset],
+                                       e->len - s->cur_offset);
+            s->cur_offset += e->len;
+            ret = 1;
+        }
+    } else
         ret = e->data[s->cur_offset++];
 
     FW_CFG_DPRINTF("read %d\n", ret);
@@ -351,6 +366,8 @@ FWCfgState *fw_cfg_init(uint32_t ctl_port, uint32_t data_port,
     fw_cfg_add_i16(s, FW_CFG_NB_CPUS, (uint16_t)smp_cpus);
     fw_cfg_add_i16(s, FW_CFG_MAX_CPUS, (uint16_t)max_cpus);
     fw_cfg_add_i16(s, FW_CFG_BOOT_MENU, (uint16_t)boot_menu);
+    fw_cfg_add_bytes(s, FW_CFG_BLIT_ADDR | FW_CFG_WRITE_CHANNEL,
+                     (uint8_t *)&blitaddr, sizeof blitaddr);
 
     return s;
 }
diff --git a/hw/fw_cfg.h b/hw/fw_cfg.h
index 4d13a4f..c64f1e8 100644
--- a/hw/fw_cfg.h
+++ b/hw/fw_cfg.h
@@ -30,11 +30,14 @@
 
 #define FW_CFG_FILE_FIRST       0x20
 #define FW_CFG_FILE_SLOTS       0x10
-#define FW_CFG_MAX_ENTRY        (FW_CFG_FILE_FIRST+FW_CFG_FILE_SLOTS)
 
+#define FW_CFG_BLIT_ADDR        0x30
+#define FW_CFG_MAX_ENTRY        (FW_CFG_BLIT_ADDR+1)
+
+#define FW_CFG_BLIT             0x2000
 #define FW_CFG_WRITE_CHANNEL    0x4000
 #define FW_CFG_ARCH_LOCAL       0x8000
-#define FW_CFG_ENTRY_MASK       ~(FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL)
+#define FW_CFG_ENTRY_MASK       ~(FW_CFG_BLIT | FW_CFG_WRITE_CHANNEL | FW_CFG_ARCH_LOCAL)
 
 #define FW_CFG_INVALID          0xffff
 
diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
index c109363..b08c69e 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -106,10 +106,10 @@ copy_kernel:
 	/* We're now running in 16-bit CS, but 32-bit ES! */
 
 	/* Load kernel and initrd */
-	read_fw_blob_addr32(FW_CFG_KERNEL)
-	read_fw_blob_addr32(FW_CFG_INITRD)
-	read_fw_blob_addr32(FW_CFG_CMDLINE)
-	read_fw_blob_addr32(FW_CFG_SETUP)
+	read_fw_blit(FW_CFG_KERNEL)
+	read_fw_blit(FW_CFG_INITRD)
+	read_fw_blit(FW_CFG_CMDLINE)
+	read_fw_blit(FW_CFG_SETUP)
 
 	/* And now jump into Linux! */
 	mov		$0, %eax
diff --git a/pc-bios/optionrom/optionrom.h b/pc-bios/optionrom/optionrom.h
index fbdd48a..a4dd49c 100644
--- a/pc-bios/optionrom/optionrom.h
+++ b/pc-bios/optionrom/optionrom.h
@@ -50,6 +50,27 @@
 	bswap		%eax
 .endm
 
+/*
+ * Write a variable from the fw_cfg device.
+ * In:          %eax
+ * Clobbers:	%edx
+ */
+.macro write_fw VAR
+        push            %eax
+        mov             $(\VAR|FW_CFG_WRITE_CHANNEL), %ax
+        mov             $BIOS_CFG_IOPORT_CFG, %dx
+        outw            %ax, (%dx)
+        pop             %eax
+        mov             $BIOS_CFG_IOPORT_DATA, %dx
+        outb            %al, (%dx)
+        shr             $8, %eax
+        outb            %al, (%dx)
+        shr             $8, %eax
+        outb            %al, (%dx)
+        shr             $8, %eax
+        outb            %al, (%dx)
+.endm
+
 #define read_fw_blob_pre(var)				\
 	read_fw		var ## _ADDR;			\
 	mov		%eax, %edi;			\
@@ -87,6 +108,22 @@
 	*/						\
 	.dc.b		0x67,0xf3,0x6c
 
+/*
+ * Fast blit data from fw_cfg device into physical memory.
+ *
+ * Works as a much faster equivalent to read_fw_blob_add32.  Except
+ * that var##_SIZE is ignored -- instead the host always blits to
+ * the end of the available data in the requested entry.
+ */
+#define read_fw_blit(var)                               \
+        read_fw         var ## _ADDR;                   \
+        write_fw        FW_CFG_BLIT_ADDR;               \
+        mov             $(var ## _DATA|FW_CFG_BLIT), %ax; \
+        mov             $BIOS_CFG_IOPORT_CFG, %edx;     \
+        outw            %ax, (%dx);                     \
+        mov             $BIOS_CFG_IOPORT_DATA, %dx;     \
+        inb             (%dx), %al
+
 #define OPTION_ROM_START					\
     .code16;						\
     .text;						\
-- 
1.7.1