[RFC,qboot,2/3] pvh: use x86/HVM direct boot ABI

Commit Message

Liam Merwick Dec. 5, 2018, 10:31 p.m. UTC

These changes (along with corresponding QEMU and Linux kernel changes)
enable a guest to be booted using the x86/HVM direct boot ABI.

QEMU parses the uncompressed kernel binary passed to it via -kernel
to read the ELF Note which contains the address to be loaded.  QEMU
then depends on qboot to populate the start_info struct needed by
the direct boot ABI and configure the guest e820 tables before
jumping to the loaded kernel entry.

Signed-off-by: George Kennedy <[e-mail]>
Signed-off-by: Liam Merwick <[e-mail]>
---
 fw_cfg.c    | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 linuxboot.c |  2 +-
 main.c      |  3 +++
 tables.c    |  9 ++++++++
 4 files changed, 84 insertions(+), 2 deletions(-)

Comments

Paolo Bonzini Dec. 6, 2018, 8:12 p.m. UTC | #1

On 05/12/18 23:31, Liam Merwick wrote:
> -static inline uint32_t ldl_p(void *p)
> +inline uint32_t ldl_p(void *p)
>  {
>  	uint32_t val;
>  	memcpy(&val, p, 4);
> diff --git a/main.c b/main.c

Can you make instead a header (memaccess.h?) with all of lduw_p, ldl_p,
stw_p, stl_p?

> 
> +
> +struct hvm_start_info start_info = {0};

Please put this declaration in linuxboot.c instead.

> 
> +#define RSDP_FILE "etc/acpi/rsdp"
> +
>  void extract_acpi(void)
>  {
>  	int id = fw_cfg_file_id("etc/table-loader");
> @@ -138,6 +143,10 @@ void extract_acpi(void)
>  		struct loader_cmd *s = &script[i];
>  		switch(script[i].cmd) {
>  		case CMD_ALLOC:
> +			if (strcmp(s->alloc.file, RSDP_FILE) == 0) {
> +				start_info.rsdp_paddr =
> +				    (uintptr_t)id_to_addr(id);
> +			}


Please instead do a memcmp with "RSD PTR" in do_alloc, and also only do
it if zone is ALLOC_FSEG.

Thanks,

Paolo

Patch

diff --git a/fw_cfg.c b/fw_cfg.c
index f5aac739b921..e13ec20d0e8b 100644
--- a/fw_cfg.c
+++ b/fw_cfg.c
@@ -8,6 +8,10 @@ 
 #include "linuxboot.h"
 #include "multiboot.h"
 #include "benchmark.h"
+#include "start_info.h"
+
+extern struct hvm_start_info start_info;
+extern inline uint32_t ldl_p(void *p);
 
 struct fw_cfg_file {
 	uint32_t size;
@@ -184,6 +188,67 @@  static void boot_multiboot_from_fw_cfg(void)
 	panic();
 }
 
+static void pvh_e820_setup()
+{
+	struct hvm_memmap_table_entry *pvh_e820p;
+	int i, pvh_e820_sz;
+
+	pvh_e820_sz = sizeof(struct hvm_memmap_table_entry) * e820->nr_map;
+
+	pvh_e820p = malloc(pvh_e820_sz);
+	memset(pvh_e820p, 0, pvh_e820_sz);
+
+	for (i = 0; i < e820->nr_map; i++) {
+		pvh_e820p[i].addr = e820->map[i].addr;
+		pvh_e820p[i].size = e820->map[i].size;
+		pvh_e820p[i].type = e820->map[i].type;
+	}
+	start_info.memmap_paddr = (uintptr_t)pvh_e820p;
+	start_info.memmap_entries = e820->nr_map;
+}
+
+void boot_pvh_from_fw_cfg(void)
+{
+	void *kernel_entry;
+	uint32_t sz;
+	struct linuxboot_args args;
+	struct hvm_modlist_entry ramdisk_mod;
+
+	start_info.magic = XEN_HVM_START_MAGIC_VALUE;
+	start_info.version = 1;
+	start_info.flags = 0;
+	start_info.nr_modules = 1;
+	start_info.reserved = 0;
+
+	fw_cfg_select(FW_CFG_CMDLINE_SIZE);
+	args.cmdline_size = fw_cfg_readl_le();
+	args.cmdline_addr = malloc(args.cmdline_size);
+	fw_cfg_read_entry(FW_CFG_CMDLINE_DATA, args.cmdline_addr,
+			  args.cmdline_size);
+	start_info.cmdline_paddr = (uintptr_t)args.cmdline_addr;
+
+	/* Use this field for pvhboot. Not used by pvhboot otherwise */
+	fw_cfg_read_entry(FW_CFG_KERNEL_DATA, &ramdisk_mod,
+			  sizeof(ramdisk_mod));
+	ramdisk_mod.cmdline_paddr = (uintptr_t)&ramdisk_mod;
+	start_info.modlist_paddr = (uintptr_t)&ramdisk_mod;
+
+	pvh_e820_setup();
+
+	fw_cfg_select(FW_CFG_KERNEL_SIZE);
+	sz = fw_cfg_readl_le();
+	if (!sz)
+		panic();
+
+	fw_cfg_select(FW_CFG_KERNEL_ENTRY);
+	kernel_entry = (void *) fw_cfg_readl_le();
+	asm volatile("movl %0, %%ebx" : : "r"(&start_info));
+
+	asm volatile("jmp *%2" : : "a" (0x2badb002),
+		     "b"(&start_info), "c"(kernel_entry));
+	panic();
+}
+
 void boot_from_fwcfg(void)
 {
 	struct linuxboot_args args;
@@ -208,8 +273,13 @@  void boot_from_fwcfg(void)
 	fw_cfg_select(FW_CFG_SETUP_DATA);
 	fw_cfg_read(args.header, sizeof(args.header));
 
-	if (!parse_bzimage(&args))
+	if (!parse_bzimage(&args)) {
+		uint8_t *header = args.header;
+
+		if (ldl_p(header) == 0x464c457f)  /* ELF magic */
+			boot_pvh_from_fw_cfg();
 		boot_multiboot_from_fw_cfg();
+	}
 
 	/* SETUP_DATA already selected */
 	if (args.setup_size > sizeof(args.header))
diff --git a/linuxboot.c b/linuxboot.c
index a5f1c4fa078d..573052cc0f78 100644
--- a/linuxboot.c
+++ b/linuxboot.c
@@ -12,7 +12,7 @@  static inline uint16_t lduw_p(void *p)
 	return val;
 }
 
-static inline uint32_t ldl_p(void *p)
+inline uint32_t ldl_p(void *p)
 {
 	uint32_t val;
 	memcpy(&val, p, 4);
diff --git a/main.c b/main.c
index 699cc1a8e6e7..725d50b94e1e 100644
--- a/main.c
+++ b/main.c
@@ -8,6 +8,9 @@ 
 #include "pflash.h"
 #include "pci.h"
 #include "benchmark.h"
+#include "start_info.h"
+
+struct hvm_start_info start_info = {0};
 
 static void set_realmode_int(int vec, void *p)
 {
diff --git a/tables.c b/tables.c
index 32b2406b9aed..47bef4125d9e 100644
--- a/tables.c
+++ b/tables.c
@@ -2,6 +2,9 @@ 
 #include "stdio.h"
 #include "fw_cfg.h"
 #include "string.h"
+#include "start_info.h"
+
+extern struct hvm_start_info start_info;
 
 struct loader_cmd {
 	uint32_t cmd;
@@ -122,6 +125,8 @@  static void do_checksum(char *file, uint32_t offset, uint32_t start, uint32_t le
 	p[offset] -= csum8(&p[start], len);
 }
 
+#define RSDP_FILE "etc/acpi/rsdp"
+
 void extract_acpi(void)
 {
 	int id = fw_cfg_file_id("etc/table-loader");
@@ -138,6 +143,10 @@  void extract_acpi(void)
 		struct loader_cmd *s = &script[i];
 		switch(script[i].cmd) {
 		case CMD_ALLOC:
+			if (strcmp(s->alloc.file, RSDP_FILE) == 0) {
+				start_info.rsdp_paddr =
+				    (uintptr_t)id_to_addr(id);
+			}
 			do_alloc(s->alloc.file, s->alloc.align, s->alloc.zone);
 			break;
 		case CMD_PTR: