Hi Stefano,
On 2/5/19 7:14 PM, Paolo Bonzini wrote:
From: Stefano Garzarella <sgarzare@redhat.com>
The new pvh.bin option rom can be used with SeaBIOS to boot
uncompressed kernel using the x86/HVM direct boot ABI.
pvh.S contains the entry point of the option rom. It runs
in real mode, loads the e820 table querying the BIOS, and
then it switches to 32bit protected mode and jumps to the
pvh_load_kernel() written in pvh_main.c.
pvh_load_kernel() loads the cmdline and kernel entry_point
using fw_cfg, then it looks for RSDP, fills the
hvm_start_info required by x86/HVM ABI, and finally jumps
to the kernel entry_point.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
---
.gitignore | 4 +
Makefile | 2 +-
pc-bios/optionrom/Makefile | 5 +-
pc-bios/optionrom/pvh.S | 200 +++++++++++++++++++++++++++++++++++++++++++
pc-bios/optionrom/pvh_main.c | 116 +++++++++++++++++++++++++
pc-bios/pvh.bin | Bin 0 -> 1536 bytes
6 files changed, 325 insertions(+), 2 deletions(-)
create mode 100644 pc-bios/optionrom/pvh.S
create mode 100644 pc-bios/optionrom/pvh_main.c
create mode 100644 pc-bios/pvh.bin
+++ b/pc-bios/optionrom/Makefile
@@ -37,7 +37,7 @@ Wa = -Wa,
ASFLAGS += -32
QEMU_CFLAGS += $(call cc-c-option, $(QEMU_CFLAGS), $(Wa)-32)
-build-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin
+build-all: multiboot.bin linuxboot.bin linuxboot_dma.bin kvmvapic.bin pvh.bin
+++ b/pc-bios/optionrom/pvh_main.c
@@ -0,0 +1,116 @@
+/*
+ * PVH 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) 2019 Red Hat Inc.
+ * Authors:
+ * Stefano Garzarella <sgarzare@redhat.com>
+ */
+
+asm (".code32"); /* this code will be executed in protected mode */
+
+#include <stddef.h>
+#include <stdint.h>
+#include "optrom.h"
+#include "optrom_fw_cfg.h"
+#include "../../include/hw/xen/start_info.h"
+
+#define RSDP_SIGNATURE 0x2052545020445352LL /* "RSD PTR " */
+#define RSDP_AREA_ADDR 0x000E0000
+#define RSDP_AREA_SIZE 2048
+#define EBDA_BASE_ADDR 0x0000040E
+#define EBDA_SIZE 1024
+
+#define E820_MAXENTRIES 128
+#define CMDLINE_BUFSIZE 4096
+
+/* e820 table filled in pvh.S using int 0x15 */
+struct pvh_e820_table {
+ uint32_t entries;
+ uint32_t reserved;
+ struct hvm_memmap_table_entry table[E820_MAXENTRIES];
+};
+
+struct pvh_e820_table pvh_e820 asm("pvh_e820") __attribute__ ((aligned));
+
+static struct hvm_start_info start_info;
+static uint8_t cmdline_buffer[CMDLINE_BUFSIZE];
+
+
+/* Search RSDP signature. */
+static uintptr_t search_rsdp(uint32_t start_addr, uint32_t end_addr)
+{
+ uint64_t *rsdp_p;
+
+ /* RSDP signature is always on a 16 byte boundary */
+ for (rsdp_p = (uint64_t *)start_addr; rsdp_p < (uint64_t *)end_addr;
+ rsdp_p += 2) {
+ if (*rsdp_p == RSDP_SIGNATURE) {
+ return (uintptr_t)rsdp_p;
+ }
+ }
+
+ return 0;
+}
gcc 10.2.1 "cc (Alpine 10.2.1_pre2) 10.2.1 20210313" reports:
pc-bios/optionrom/pvh_main.c: In function 'search_rsdp':
pc-bios/optionrom/pvh_main.c:61:21: warning: comparison is always false
due to limited range of data type [-Wtype-limits]
61 | if (*rsdp_p == RSDP_SIGNATURE) {
| ^~
Can you have a look?