pvh: Boot uncompressed kernel using direct boot ABI
These changes (along with corresponding Linux kernel and qboot changes) enable a guest to be booted using the x86/HVM direct boot ABI. This commit adds a load_elfboot() routine to pass the size and location of the kernel entry point to qboot (which will fill in the start_info struct information needed to to boot the guest). Having loaded the ELF binary, load_linux() will run qboot which continues the boot. The address for the kernel entry point is read from an ELF Note in the uncompressed kernel binary by a helper routine passed to load_elf(). Co-developed-by: George Kennedy <George.Kennedy@oracle.com> Signed-off-by: George Kennedy <George.Kennedy@oracle.com> Signed-off-by: Liam Merwick <liam.merwick@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Liam Merwick
Paolo Bonzini
parent
20a965067f
commit
ab969087da
135
hw/i386/pc.c
135
hw/i386/pc.c
@ -54,6 +54,7 @@
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#include "sysemu/qtest.h"
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#include "kvm_i386.h"
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#include "hw/xen/xen.h"
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#include "hw/xen/start_info.h"
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#include "ui/qemu-spice.h"
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#include "exec/memory.h"
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#include "exec/address-spaces.h"
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@ -110,6 +111,9 @@ static struct e820_entry *e820_table;
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static unsigned e820_entries;
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struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
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/* Physical Address of PVH entry point read from kernel ELF NOTE */
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static size_t pvh_start_addr;
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GlobalProperty pc_compat_3_1[] = {
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{ "intel-iommu", "dma-drain", "off" },
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{ "Opteron_G3" "-" TYPE_X86_CPU, "rdtscp", "off" },
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@ -1069,6 +1073,109 @@ struct setup_data {
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uint8_t data[0];
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} __attribute__((packed));
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/*
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* The entry point into the kernel for PVH boot is different from
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* the native entry point. The PVH entry is defined by the x86/HVM
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* direct boot ABI and is available in an ELFNOTE in the kernel binary.
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*
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* This function is passed to load_elf() when it is called from
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* load_elfboot() which then additionally checks for an ELF Note of
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* type XEN_ELFNOTE_PHYS32_ENTRY and passes it to this function to
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* parse the PVH entry address from the ELF Note.
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*
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* Due to trickery in elf_opts.h, load_elf() is actually available as
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* load_elf32() or load_elf64() and this routine needs to be able
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* to deal with being called as 32 or 64 bit.
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*
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* The address of the PVH entry point is saved to the 'pvh_start_addr'
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* global variable. (although the entry point is 32-bit, the kernel
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* binary can be either 32-bit or 64-bit).
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*/
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static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64)
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{
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size_t *elf_note_data_addr;
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/* Check if ELF Note header passed in is valid */
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if (arg1 == NULL) {
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return 0;
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}
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if (is64) {
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struct elf64_note *nhdr64 = (struct elf64_note *)arg1;
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uint64_t nhdr_size64 = sizeof(struct elf64_note);
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uint64_t phdr_align = *(uint64_t *)arg2;
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uint64_t nhdr_namesz = nhdr64->n_namesz;
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elf_note_data_addr =
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((void *)nhdr64) + nhdr_size64 +
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QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
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} else {
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struct elf32_note *nhdr32 = (struct elf32_note *)arg1;
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uint32_t nhdr_size32 = sizeof(struct elf32_note);
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uint32_t phdr_align = *(uint32_t *)arg2;
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uint32_t nhdr_namesz = nhdr32->n_namesz;
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elf_note_data_addr =
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((void *)nhdr32) + nhdr_size32 +
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QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
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}
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pvh_start_addr = *elf_note_data_addr;
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return pvh_start_addr;
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}
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static bool load_elfboot(const char *kernel_filename,
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int kernel_file_size,
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uint8_t *header,
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size_t pvh_xen_start_addr,
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FWCfgState *fw_cfg)
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{
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uint32_t flags = 0;
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uint32_t mh_load_addr = 0;
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uint32_t elf_kernel_size = 0;
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uint64_t elf_entry;
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uint64_t elf_low, elf_high;
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int kernel_size;
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if (ldl_p(header) != 0x464c457f) {
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return false; /* no elfboot */
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}
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bool elf_is64 = header[EI_CLASS] == ELFCLASS64;
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flags = elf_is64 ?
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((Elf64_Ehdr *)header)->e_flags : ((Elf32_Ehdr *)header)->e_flags;
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if (flags & 0x00010004) { /* LOAD_ELF_HEADER_HAS_ADDR */
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error_report("elfboot unsupported flags = %x", flags);
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exit(1);
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}
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uint64_t elf_note_type = XEN_ELFNOTE_PHYS32_ENTRY;
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kernel_size = load_elf(kernel_filename, read_pvh_start_addr,
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NULL, &elf_note_type, &elf_entry,
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&elf_low, &elf_high, 0, I386_ELF_MACHINE,
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0, 0);
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if (kernel_size < 0) {
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error_report("Error while loading elf kernel");
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exit(1);
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}
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mh_load_addr = elf_low;
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elf_kernel_size = elf_high - elf_low;
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if (pvh_start_addr == 0) {
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error_report("Error loading uncompressed kernel without PVH ELF Note");
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exit(1);
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}
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fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ENTRY, pvh_start_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, mh_load_addr);
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fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, elf_kernel_size);
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return true;
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}
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static void load_linux(PCMachineState *pcms,
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FWCfgState *fw_cfg)
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{
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@ -1108,6 +1215,34 @@ static void load_linux(PCMachineState *pcms,
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if (ldl_p(header+0x202) == 0x53726448) {
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protocol = lduw_p(header+0x206);
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} else {
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/*
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* Check if the file is an uncompressed kernel file (ELF) and load it,
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* saving the PVH entry point used by the x86/HVM direct boot ABI.
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* If load_elfboot() is successful, populate the fw_cfg info.
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*/
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if (load_elfboot(kernel_filename, kernel_size,
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header, pvh_start_addr, fw_cfg)) {
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struct hvm_modlist_entry ramdisk_mod = { 0 };
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fclose(f);
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fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE,
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strlen(kernel_cmdline) + 1);
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fw_cfg_add_string(fw_cfg, FW_CFG_CMDLINE_DATA, kernel_cmdline);
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assert(machine->device_memory != NULL);
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ramdisk_mod.paddr = machine->device_memory->base;
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ramdisk_mod.size =
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memory_region_size(&machine->device_memory->mr);
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fw_cfg_add_bytes(fw_cfg, FW_CFG_KERNEL_DATA, &ramdisk_mod,
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sizeof(ramdisk_mod));
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fw_cfg_add_i32(fw_cfg, FW_CFG_SETUP_SIZE, sizeof(header));
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fw_cfg_add_bytes(fw_cfg, FW_CFG_SETUP_DATA,
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header, sizeof(header));
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return;
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}
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/* This looks like a multiboot kernel. If it is, let's stop
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treating it like a Linux kernel. */
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if (load_multiboot(fw_cfg, f, kernel_filename, initrd_filename,
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@ -1640,6 +1640,16 @@ typedef struct elf64_shdr {
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#define NT_ARM_HW_WATCH 0x403 /* ARM hardware watchpoint registers */
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#define NT_ARM_SYSTEM_CALL 0x404 /* ARM system call number */
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/*
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* Physical entry point into the kernel.
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*
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* 32bit entry point into the kernel. When requested to launch the
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* guest kernel, use this entry point to launch the guest in 32-bit
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* protected mode with paging disabled.
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*
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* [ Corresponding definition in Linux kernel: include/xen/interface/elfnote.h ]
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*/
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#define XEN_ELFNOTE_PHYS32_ENTRY 18 /* 0x12 */
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/* Note header in a PT_NOTE section */
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typedef struct elf32_note {
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