[Qemu-devel] [PATCH v7 2/2] Add optionrom compatible with fw_cfg DMA version

["Richard W.M. Jones" <rjones@redhat.com>]

From: Marc Marí <markmb@redhat.com>

This optionrom is based on linuxboot.S.

Signed-off-by: Marc Marí <markmb@redhat.com>
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
---
 .gitignore                        |   4 +
 hw/i386/pc.c                      |  10 +-
 hw/nvram/fw_cfg.c                 |   2 +-
 include/hw/nvram/fw_cfg.h         |   1 +
 pc-bios/optionrom/Makefile        |  13 +-
 pc-bios/optionrom/linuxboot_dma.c | 291 ++++++++++++++++++++++++++++++++++++++
 6 files changed, 316 insertions(+), 5 deletions(-)
 create mode 100644 pc-bios/optionrom/linuxboot_dma.c

diff --git a/.gitignore b/.gitignore
index 88a80ff..101d1e0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -94,6 +94,10 @@
 /pc-bios/optionrom/linuxboot.bin
 /pc-bios/optionrom/linuxboot.raw
 /pc-bios/optionrom/linuxboot.img
+/pc-bios/optionrom/linuxboot_dma.asm
+/pc-bios/optionrom/linuxboot_dma.bin
+/pc-bios/optionrom/linuxboot_dma.raw
+/pc-bios/optionrom/linuxboot_dma.img
 /pc-bios/optionrom/multiboot.asm
 /pc-bios/optionrom/multiboot.bin
 /pc-bios/optionrom/multiboot.raw
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 99437e0..098d571 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -999,8 +999,13 @@ static void load_linux(PCMachineState *pcms,
     fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_SIZE, setup_size);
     fw_cfg_add_bytes(fw_cfg, FW_CFG_SETUP_DATA, setup, setup_size);
 
-    option_rom[nb_option_roms].name = "linuxboot.bin";
-    option_rom[nb_option_roms].bootindex = 0;
+    if (fw_cfg_dma_enabled(fw_cfg)) {
+        option_rom[nb_option_roms].name = "linuxboot_dma.bin";
+        option_rom[nb_option_roms].bootindex = 0;
+    } else {
+        option_rom[nb_option_roms].name = "linuxboot.bin";
+        option_rom[nb_option_roms].bootindex = 0;
+    }
     nb_option_roms++;
 }
 
@@ -1263,6 +1268,7 @@ void xen_load_linux(PCMachineState *pcms)
     load_linux(pcms, fw_cfg);
     for (i = 0; i < nb_option_roms; i++) {
         assert(!strcmp(option_rom[i].name, "linuxboot.bin") ||
+               !strcmp(option_rom[i].name, "linuxboot_dma.bin") ||
                !strcmp(option_rom[i].name, "multiboot.bin"));
         rom_add_option(option_rom[i].name, option_rom[i].bootindex);
     }
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 999f480..114aea8 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -551,7 +551,7 @@ static bool is_version_1(void *opaque, int version_id)
     return version_id == 1;
 }
 
-static bool fw_cfg_dma_enabled(void *opaque)
+bool fw_cfg_dma_enabled(void *opaque)
 {
     FWCfgState *s = opaque;
 
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index d008112..5c27a1f 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -182,5 +182,6 @@ FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
                                  hwaddr dma_addr, AddressSpace *dma_as);
 
 FWCfgState *fw_cfg_find(void);
+bool fw_cfg_dma_enabled(void *opaque);
 
 #endif
diff --git a/pc-bios/optionrom/Makefile b/pc-bios/optionrom/Makefile
index ce4852a..a51dd6e 100644
--- a/pc-bios/optionrom/Makefile
+++ b/pc-bios/optionrom/Makefile
@@ -13,15 +13,24 @@ CFLAGS := -Wall -Wstrict-prototypes -Werror -fomit-frame-pointer -fno-builtin
 CFLAGS += -I$(SRC_PATH)
 CFLAGS += $(call cc-option, $(CFLAGS), -fno-stack-protector)
 CFLAGS += $(CFLAGS_NOPIE)
+CFLAGS += -m16
 QEMU_CFLAGS = $(CFLAGS)
 
-build-all: multiboot.bin linuxboot.bin kvmvapic.bin
+ASFLAGS += -32
+
+build-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin
 
 # suppress auto-removal of intermediate files
 .SECONDARY:
 
+ifdef CONFIG_WIN32
+LD_EMULATION = i386pe
+else
+LD_EMULATION = elf_i386
+endif
+
 %.img: %.o
-	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
+	$(call quiet-command,$(LD) $(LDFLAGS_NOPIE) -m $(LD_EMULATION) -Ttext 0 -e _start -s -o $@ $<,"  Building $(TARGET_DIR)$@")
 
 %.raw: %.img
 	$(call quiet-command,$(OBJCOPY) -O binary -j .text $< $@,"  Building $(TARGET_DIR)$@")
diff --git a/pc-bios/optionrom/linuxboot_dma.c b/pc-bios/optionrom/linuxboot_dma.c
new file mode 100644
index 0000000..f0741a1
--- /dev/null
+++ b/pc-bios/optionrom/linuxboot_dma.c
@@ -0,0 +1,291 @@
+/*
+ * Linux Boot Option ROM for fw_cfg DMA
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright (c) 2015-2016 Red Hat Inc.
+ *   Authors:
+ *     Marc Marí <markmb@redhat.com>
+ *     Richard W.M. Jones <rjones@redhat.com>
+ */
+
+asm(
+".text\n"
+".global _start\n"
+"_start:\n"
+"   .short 0xaa55\n"
+"   .byte 0\n" /* size in 512 units, filled in by signrom.py */
+"   .byte 0xcb\n" /* far return without prefix */
+"   .org 0x18\n"
+"   .short 0\n"
+"   .short _pnph\n"
+"_pnph:\n"
+"   .ascii \"$PnP\"\n"
+"   .byte 0x01\n"
+"   .byte (_pnph_len / 16)\n"
+"   .short 0x0000\n"
+"   .byte 0x00\n"
+"   .byte 0x00\n"
+"   .long 0x00000000\n"
+"   .short _manufacturer\n"
+"   .short _product\n"
+"   .long 0x00000000\n"
+"   .short 0x0000\n"
+"   .short 0x0000\n"
+"   .short _bev\n"
+"   .short 0x0000\n"
+"   .short 0x0000\n"
+"   .equ _pnph_len, . - _pnph\n"
+"_manufacturer:\n"
+"    .asciz \"QEMU\"\n"
+"_product:\n"
+"    .asciz \"Linux loader DMA\"\n"
+"   .align 4, 0\n"
+"_bev:\n"
+"   cli\n"
+"   cld\n"
+"   jmp load_kernel\n"
+);
+
+#include "../../include/hw/nvram/fw_cfg_keys.h"
+
+/* QEMU_CFG_DMA_CONTROL bits */
+#define BIOS_CFG_DMA_CTL_ERROR   0x01
+#define BIOS_CFG_DMA_CTL_READ    0x02
+#define BIOS_CFG_DMA_CTL_SKIP    0x04
+#define BIOS_CFG_DMA_CTL_SELECT  0x08
+
+#define BIOS_CFG_DMA_ADDR_HIGH 0x514
+#define BIOS_CFG_DMA_ADDR_LOW  0x518
+
+#define uint64_t unsigned long long
+#define uint32_t unsigned int
+#define uint16_t unsigned short
+
+#define barrier() asm("" : : : "memory")
+
+typedef struct FWCfgDmaAccess {
+    uint32_t control;
+    uint32_t length;
+    uint64_t address;
+} __attribute__((packed)) FWCfgDmaAccess;
+
+static inline void outl(uint32_t value, uint16_t port)
+{
+    asm("outl %0, %w1" : : "a"(value), "Nd"(port));
+}
+
+static inline void set_es(void *addr)
+{
+    uint32_t seg = (uint32_t)addr >> 4;
+    asm("movl %0, %%es" : : "r"(seg));
+}
+
+#ifdef __clang__
+#define ADDR32
+#else
+#define ADDR32 "addr32 "
+#endif
+
+static inline uint16_t readw_es(uint16_t offset)
+{
+    uint16_t val;
+    asm(ADDR32"movw %%es:(%1), %0" : "=r"(val) : "r"((uint32_t)offset));
+    barrier();
+    return val;
+}
+
+static inline uint32_t readl_es(uint16_t offset)
+{
+    uint32_t val;
+    asm(ADDR32"movl %%es:(%1), %0" : "=r"(val) : "r"((uint32_t)offset));
+    barrier();
+    return val;
+}
+
+static inline void writel_es(uint16_t offset, uint32_t val)
+{
+    barrier();
+    asm(ADDR32"movl %0, %%es:(%1)" : : "r"(val), "r"((uint32_t)offset));
+}
+
+static inline uint32_t bswap32(uint32_t x)
+{
+    return
+        ((x & 0x000000ffU) << 24) |
+        ((x & 0x0000ff00U) <<  8) |
+        ((x & 0x00ff0000U) >>  8) |
+        ((x & 0xff000000U) >> 24);
+}
+
+static inline uint64_t bswap64(uint64_t x)
+{
+    return
+        ((x & 0x00000000000000ffULL) << 56) |
+        ((x & 0x000000000000ff00ULL) << 40) |
+        ((x & 0x0000000000ff0000ULL) << 24) |
+        ((x & 0x00000000ff000000ULL) <<  8) |
+        ((x & 0x000000ff00000000ULL) >>  8) |
+        ((x & 0x0000ff0000000000ULL) >> 24) |
+        ((x & 0x00ff000000000000ULL) >> 40) |
+        ((x & 0xff00000000000000ULL) >> 56);
+}
+
+static inline uint64_t cpu_to_be64(uint64_t x)
+{
+    return bswap64(x);
+}
+
+static inline uint32_t cpu_to_be32(uint32_t x)
+{
+    return bswap32(x);
+}
+
+static inline uint32_t be32_to_cpu(uint32_t x)
+{
+    return bswap32(x);
+}
+
+static void bios_cfg_read_entry(void *buf, uint16_t entry, uint32_t len)
+{
+    FWCfgDmaAccess access;
+    uint32_t control = (entry << 16) | BIOS_CFG_DMA_CTL_SELECT
+                        | BIOS_CFG_DMA_CTL_READ;
+
+    access.address = cpu_to_be64((uint64_t)(uint32_t)buf);
+    access.length = cpu_to_be32(len);
+    access.control = cpu_to_be32(control);
+
+    barrier();
+
+    outl(cpu_to_be32((uint32_t)&access), BIOS_CFG_DMA_ADDR_LOW);
+
+    while (be32_to_cpu(access.control) & ~BIOS_CFG_DMA_CTL_ERROR) {
+        barrier();
+    }
+}
+
+/* Return top of memory using BIOS function E801. */
+static uint32_t get_e801_addr(void)
+{
+    uint16_t ax, bx, cx, dx;
+    uint32_t ret;
+
+    asm("int $0x15\n"
+        : "=a"(ax), "=b"(bx), "=c"(cx), "=d"(dx)
+        : "a"(0xe801), "b"(0), "c"(0), "d"(0));
+
+    /* Not SeaBIOS, but in theory a BIOS could return CX=DX=0 in which
+     * case we need to use the result from AX & BX instead.
+     */
+    if (cx == 0 && dx == 0) {
+        cx = ax;
+        dx = bx;
+    }
+
+    if (dx) {
+        /* DX = extended memory above 16M, in 64K units.
+         * Convert it to bytes and return.
+         */
+        ret = ((uint32_t)dx + 256 /* 16M in 64K units */) << 16;
+    } else {
+        /* This is a fallback path for machines with <= 16MB of RAM,
+         * which probably would never be the case, but deal with it
+         * anyway.
+         *
+         * CX = extended memory between 1M and 16M, in kilobytes
+         * Convert it to bytes and return.
+         */
+        ret = ((uint32_t)cx + 1024 /* 1M in K */) << 10;
+    }
+
+    return ret;
+}
+
+void load_kernel(void)
+{
+    void *setup_addr;
+    void *initrd_addr;
+    void *kernel_addr;
+    void *cmdline_addr;
+    uint32_t setup_size;
+    uint32_t initrd_size;
+    uint32_t kernel_size;
+    uint32_t cmdline_size;
+    uint32_t initrd_end_page, max_allowed_page;
+    uint32_t segment_addr, stack_addr;
+
+    bios_cfg_read_entry(&setup_addr, FW_CFG_SETUP_ADDR, 4);
+    bios_cfg_read_entry(&setup_size, FW_CFG_SETUP_SIZE, 4);
+    bios_cfg_read_entry(setup_addr, FW_CFG_SETUP_DATA, setup_size);
+
+    set_es(setup_addr);
+
+    /* For protocol < 0x203 we don't have initrd_max ... */
+    if (readw_es(0x206) < 0x203) {
+        /* ... so we assume initrd_max = 0x37ffffff. */
+        writel_es(0x22c, 0x37ffffff);
+    }
+
+    bios_cfg_read_entry(&initrd_addr, FW_CFG_INITRD_ADDR, 4);
+    bios_cfg_read_entry(&initrd_size, FW_CFG_INITRD_SIZE, 4);
+
+    initrd_end_page = ((uint32_t)(initrd_addr + initrd_size) & -4096);
+    max_allowed_page = (readl_es(0x22c) & -4096);
+
+    if (initrd_end_page != 0 && max_allowed_page != 0 &&
+        initrd_end_page != max_allowed_page) {
+        /* Initrd at the end of memory. Compute better initrd address
+         * based on e801 data
+         */
+        initrd_addr = (void *)((get_e801_addr() - initrd_size) & -4096);
+        writel_es(0x218, (uint32_t)initrd_addr);
+
+    }
+
+    bios_cfg_read_entry(initrd_addr, FW_CFG_INITRD_DATA, initrd_size);
+
+    bios_cfg_read_entry(&kernel_addr, FW_CFG_KERNEL_ADDR, 4);
+    bios_cfg_read_entry(&kernel_size, FW_CFG_KERNEL_SIZE, 4);
+    bios_cfg_read_entry(kernel_addr, FW_CFG_KERNEL_DATA, kernel_size);
+
+    bios_cfg_read_entry(&cmdline_addr, FW_CFG_CMDLINE_ADDR, 4);
+    bios_cfg_read_entry(&cmdline_size, FW_CFG_CMDLINE_SIZE, 4);
+    bios_cfg_read_entry(cmdline_addr, FW_CFG_CMDLINE_DATA, cmdline_size);
+
+    /* Boot linux */
+    segment_addr = ((uint32_t)setup_addr >> 4);
+    stack_addr = (uint32_t)(cmdline_addr - setup_addr - 16);
+
+    /* As we are changing critical registers, we cannot leave freedom to the
+     * compiler.
+     */
+    asm("movw %%ax, %%ds\n"
+        "movw %%ax, %%es\n"
+        "movw %%ax, %%fs\n"
+        "movw %%ax, %%gs\n"
+        "movw %%ax, %%ss\n"
+        "movl %%ebx, %%esp\n"
+        "addw $0x20, %%ax\n"
+        "pushw %%ax\n" /* CS */
+        "pushw $0\n" /* IP */
+        /* Clear registers and jump to Linux */
+        "xor %%ebx, %%ebx\n"
+        "xor %%ecx, %%ecx\n"
+        "xor %%edx, %%edx\n"
+        "xor %%edi, %%edi\n"
+        "xor %%ebp, %%ebp\n"
+        "lretw\n"
+        : : "a"(segment_addr), "b"(stack_addr));
+}
-- 
2.7.4