Re: [PATCH v4 1/8] hw/i386: Factorize PVH related functions

[Sergio Lopez]

Philippe Mathieu-Daudé <address@hidden> writes:

> Hi Sergio,
>
> On 9/24/19 2:44 PM, Sergio Lopez wrote:
>> Extract PVH related functions from pc.c, and put them in pvh.c, so
>> they can be shared with other components.
>> 
>> Signed-off-by: Sergio Lopez <address@hidden>
>> ---
>>  hw/i386/Makefile.objs |   1 +
>>  hw/i386/pc.c          | 120 +++++-------------------------------------
>>  hw/i386/pvh.c         | 113 +++++++++++++++++++++++++++++++++++++++
>>  hw/i386/pvh.h         |  10 ++++
>>  4 files changed, 136 insertions(+), 108 deletions(-)
>>  create mode 100644 hw/i386/pvh.c
>>  create mode 100644 hw/i386/pvh.h
>> 
>> diff --git a/hw/i386/Makefile.objs b/hw/i386/Makefile.objs
>> index 5d9c9efd5f..c5f20bbd72 100644
>> --- a/hw/i386/Makefile.objs
>> +++ b/hw/i386/Makefile.objs
>> @@ -1,5 +1,6 @@
>>  obj-$(CONFIG_KVM) += kvm/
>>  obj-y += multiboot.o
>> +obj-y += pvh.o
>>  obj-y += pc.o
>>  obj-$(CONFIG_I440FX) += pc_piix.o
>>  obj-$(CONFIG_Q35) += pc_q35.o
>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>> index bad866fe44..10e4ced0c6 100644
>> --- a/hw/i386/pc.c
>> +++ b/hw/i386/pc.c
>> @@ -42,6 +42,7 @@
>>  #include "elf.h"
>>  #include "migration/vmstate.h"
>>  #include "multiboot.h"
>> +#include "pvh.h"
>>  #include "hw/timer/mc146818rtc.h"
>>  #include "hw/dma/i8257.h"
>>  #include "hw/timer/i8254.h"
>> @@ -116,9 +117,6 @@ static struct e820_entry *e820_table;
>>  static unsigned e820_entries;
>>  struct hpet_fw_config hpet_cfg = {.count = UINT8_MAX};
>>  
>> -/* Physical Address of PVH entry point read from kernel ELF NOTE */
>> -static size_t pvh_start_addr;
>> -
>>  GlobalProperty pc_compat_4_1[] = {};
>>  const size_t pc_compat_4_1_len = G_N_ELEMENTS(pc_compat_4_1);
>>  
>> @@ -1076,109 +1074,6 @@ struct setup_data {
>>      uint8_t data[0];
>>  } __attribute__((packed));
>>  
>> -
>> -/*
>> - * The entry point into the kernel for PVH boot is different from
>> - * the native entry point.  The PVH entry is defined by the x86/HVM
>> - * direct boot ABI and is available in an ELFNOTE in the kernel binary.
>> - *
>> - * This function is passed to load_elf() when it is called from
>> - * load_elfboot() which then additionally checks for an ELF Note of
>> - * type XEN_ELFNOTE_PHYS32_ENTRY and passes it to this function to
>> - * parse the PVH entry address from the ELF Note.
>> - *
>> - * Due to trickery in elf_opts.h, load_elf() is actually available as
>> - * load_elf32() or load_elf64() and this routine needs to be able
>> - * to deal with being called as 32 or 64 bit.
>> - *
>> - * The address of the PVH entry point is saved to the 'pvh_start_addr'
>> - * global variable.  (although the entry point is 32-bit, the kernel
>> - * binary can be either 32-bit or 64-bit).
>> - */
>> -static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64)
>> -{
>> -    size_t *elf_note_data_addr;
>> -
>> -    /* Check if ELF Note header passed in is valid */
>> -    if (arg1 == NULL) {
>> -        return 0;
>> -    }
>> -
>> -    if (is64) {
>> -        struct elf64_note *nhdr64 = (struct elf64_note *)arg1;
>> -        uint64_t nhdr_size64 = sizeof(struct elf64_note);
>> -        uint64_t phdr_align = *(uint64_t *)arg2;
>> -        uint64_t nhdr_namesz = nhdr64->n_namesz;
>> -
>> -        elf_note_data_addr =
>> -            ((void *)nhdr64) + nhdr_size64 +
>> -            QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
>> -    } else {
>> -        struct elf32_note *nhdr32 = (struct elf32_note *)arg1;
>> -        uint32_t nhdr_size32 = sizeof(struct elf32_note);
>> -        uint32_t phdr_align = *(uint32_t *)arg2;
>> -        uint32_t nhdr_namesz = nhdr32->n_namesz;
>> -
>> -        elf_note_data_addr =
>> -            ((void *)nhdr32) + nhdr_size32 +
>> -            QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
>> -    }
>> -
>> -    pvh_start_addr = *elf_note_data_addr;
>> -
>> -    return pvh_start_addr;
>> -}
>> -
>> -static bool load_elfboot(const char *kernel_filename,
>> -                   int kernel_file_size,
>> -                   uint8_t *header,
>> -                   size_t pvh_xen_start_addr,
>> -                   FWCfgState *fw_cfg)
>> -{
>> -    uint32_t flags = 0;
>> -    uint32_t mh_load_addr = 0;
>> -    uint32_t elf_kernel_size = 0;
>> -    uint64_t elf_entry;
>> -    uint64_t elf_low, elf_high;
>> -    int kernel_size;
>> -
>> -    if (ldl_p(header) != 0x464c457f) {
>> -        return false; /* no elfboot */
>> -    }
>> -
>> -    bool elf_is64 = header[EI_CLASS] == ELFCLASS64;
>> -    flags = elf_is64 ?
>> -        ((Elf64_Ehdr *)header)->e_flags : ((Elf32_Ehdr *)header)->e_flags;
>> -
>> -    if (flags & 0x00010004) { /* LOAD_ELF_HEADER_HAS_ADDR */
>> -        error_report("elfboot unsupported flags = %x", flags);
>> -        exit(1);
>> -    }
>> -
>> -    uint64_t elf_note_type = XEN_ELFNOTE_PHYS32_ENTRY;
>> -    kernel_size = load_elf(kernel_filename, read_pvh_start_addr,
>> -                           NULL, &elf_note_type, &elf_entry,
>> -                           &elf_low, &elf_high, 0, I386_ELF_MACHINE,
>> -                           0, 0);
>> -
>> -    if (kernel_size < 0) {
>> -        error_report("Error while loading elf kernel");
>> -        exit(1);
>> -    }
>> -    mh_load_addr = elf_low;
>> -    elf_kernel_size = elf_high - elf_low;
>> -
>> -    if (pvh_start_addr == 0) {
>> -        error_report("Error loading uncompressed kernel without PVH ELF 
>> Note");
>> -        exit(1);
>> -    }
>> -    fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ENTRY, pvh_start_addr);
>> -    fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, mh_load_addr);
>> -    fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, elf_kernel_size);
>> -
>> -    return true;
>> -}
>> -
>>  static void load_linux(PCMachineState *pcms,
>>                         FWCfgState *fw_cfg)
>>  {
>> @@ -1218,6 +1113,9 @@ static void load_linux(PCMachineState *pcms,
>>      if (ldl_p(header+0x202) == 0x53726448) {
>>          protocol = lduw_p(header+0x206);
>>      } else {
>> +        size_t pvh_start_addr;
>> +        uint32_t mh_load_addr = 0;
>> +        uint32_t elf_kernel_size = 0;
>>          /*
>>           * This could be a multiboot kernel. If it is, let's stop treating 
>> it
>>           * like a Linux kernel.
>> @@ -1235,10 +1133,16 @@ static void load_linux(PCMachineState *pcms,
>>           * If load_elfboot() is successful, populate the fw_cfg info.
>>           */
>>          if (pcmc->pvh_enabled &&
>> -            load_elfboot(kernel_filename, kernel_size,
>> -                         header, pvh_start_addr, fw_cfg)) {
>> +            pvh_load_elfboot(kernel_filename,
>> +                             &mh_load_addr, &elf_kernel_size)) {
>>              fclose(f);
>>  
>> +            pvh_start_addr = pvh_get_start_addr();
>> +
>> +            fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ENTRY, pvh_start_addr);
>> +            fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, mh_load_addr);
>> +            fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_SIZE, elf_kernel_size);
>> +
>>              fw_cfg_add_i32(fw_cfg, FW_CFG_CMDLINE_SIZE,
>>                  strlen(kernel_cmdline) + 1);
>>              fw_cfg_add_string(fw_cfg, FW_CFG_CMDLINE_DATA, kernel_cmdline);
>> diff --git a/hw/i386/pvh.c b/hw/i386/pvh.c
>> new file mode 100644
>> index 0000000000..1c81727811
>> --- /dev/null
>> +++ b/hw/i386/pvh.c
>> @@ -0,0 +1,113 @@
>> +/*
>> + * PVH Boot Helper
>> + *
>> + * Copyright (C) 2019 Oracle
>> + * Copyright (C) 2019 Red Hat, Inc
>> + *
>> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
>> + * See the COPYING file in the top-level directory.
>> + *
>> + */
>> +
>> +#include "qemu/osdep.h"
>> +#include "qemu/units.h"
>> +#include "qemu/error-report.h"
>> +#include "hw/loader.h"
>> +#include "cpu.h"
>> +#include "elf.h"
>> +#include "pvh.h"
>> +
>> +static size_t pvh_start_addr;
>> +
>> +size_t pvh_get_start_addr(void)
>> +{
>> +    return pvh_start_addr;
>> +}
>> +
>> +/*
>> + * The entry point into the kernel for PVH boot is different from
>> + * the native entry point.  The PVH entry is defined by the x86/HVM
>> + * direct boot ABI and is available in an ELFNOTE in the kernel binary.
>> + *
>> + * This function is passed to load_elf() when it is called from
>> + * load_elfboot() which then additionally checks for an ELF Note of
>> + * type XEN_ELFNOTE_PHYS32_ENTRY and passes it to this function to
>> + * parse the PVH entry address from the ELF Note.
>> + *
>> + * Due to trickery in elf_opts.h, load_elf() is actually available as
>> + * load_elf32() or load_elf64() and this routine needs to be able
>> + * to deal with being called as 32 or 64 bit.
>> + *
>> + * The address of the PVH entry point is saved to the 'pvh_start_addr'
>> + * global variable.  (although the entry point is 32-bit, the kernel
>> + * binary can be either 32-bit or 64-bit).
>> + */
>> +
>> +static uint64_t read_pvh_start_addr(void *arg1, void *arg2, bool is64)
>> +{
>> +    size_t *elf_note_data_addr;
>> +
>> +    /* Check if ELF Note header passed in is valid */
>> +    if (arg1 == NULL) {
>> +        return 0;
>> +    }
>> +
>> +    if (is64) {
>> +        struct elf64_note *nhdr64 = (struct elf64_note *)arg1;
>> +        uint64_t nhdr_size64 = sizeof(struct elf64_note);
>> +        uint64_t phdr_align = *(uint64_t *)arg2;
>> +        uint64_t nhdr_namesz = nhdr64->n_namesz;
>> +
>> +        elf_note_data_addr =
>> +            ((void *)nhdr64) + nhdr_size64 +
>> +            QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
>> +    } else {
>> +        struct elf32_note *nhdr32 = (struct elf32_note *)arg1;
>> +        uint32_t nhdr_size32 = sizeof(struct elf32_note);
>> +        uint32_t phdr_align = *(uint32_t *)arg2;
>> +        uint32_t nhdr_namesz = nhdr32->n_namesz;
>> +
>> +        elf_note_data_addr =
>> +            ((void *)nhdr32) + nhdr_size32 +
>> +            QEMU_ALIGN_UP(nhdr_namesz, phdr_align);
>> +    }
>> +
>> +    pvh_start_addr = *elf_note_data_addr;
>> +
>> +    return pvh_start_addr;
>> +}
>> +
>> +bool pvh_load_elfboot(const char *kernel_filename,
>> +                      uint32_t *mh_load_addr,
>> +                      uint32_t *elf_kernel_size)
>> +{
>> +    uint64_t elf_entry;
>> +    uint64_t elf_low, elf_high;
>> +    int kernel_size;
>> +    uint64_t elf_note_type = XEN_ELFNOTE_PHYS32_ENTRY;
>> +
>> +    kernel_size = load_elf(kernel_filename, read_pvh_start_addr,
>> +                           NULL, &elf_note_type, &elf_entry,
>> +                           &elf_low, &elf_high, 0, I386_ELF_MACHINE,
>> +                           0, 0);
>> +
>> +    if (kernel_size < 0) {
>> +        error_report("Error while loading elf kernel");
>> +        return false;
>> +    }
>> +
>> +    if (pvh_start_addr == 0) {
>> +        error_report("Error loading uncompressed kernel without PVH ELF 
>> Note");
>> +        return false;
>> +    }
>> +
>> +    if (mh_load_addr) {
>> +        *mh_load_addr = elf_low;
>> +    }
>> +
>> +    if (elf_kernel_size) {
>> +        *elf_kernel_size = elf_high - elf_low;
>> +    }
>> +
>> +    return true;
>> +}
>> diff --git a/hw/i386/pvh.h b/hw/i386/pvh.h
>> new file mode 100644
>> index 0000000000..ada67ff6e8
>> --- /dev/null
>> +++ b/hw/i386/pvh.h
>> @@ -0,0 +1,10 @@
>
> License missing.

I'm a bit confused about the policy for license blocks in headers, as
some do have it, while others don't (i.e. multiboot.h and acpi-build.h).

>> +#ifndef HW_I386_PVH_H
>> +#define HW_I386_PVH_H
>> +
>> +size_t pvh_get_start_addr(void);
>> +
>> +bool pvh_load_elfboot(const char *kernel_filename,
>> +                      uint32_t *mh_load_addr,
>> +                      uint32_t *elf_kernel_size);
>
> Can you document these functions?

Sure.

Thanks,
Sergio.

>> +
>> +#endif
>>

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