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Re: [PATCH v4 1/8] hw/i386: Factorize PVH related functions
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From: |
Stefano Garzarella |
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Subject: |
Re: [PATCH v4 1/8] hw/i386: Factorize PVH related functions |
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Date: |
Wed, 25 Sep 2019 11:29:52 +0200 |
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User-agent: |
NeoMutt/20180716 |
On Wed, Sep 25, 2019 at 11:00:30AM +0200, Sergio Lopez wrote:
> Stefano Garzarella <address@hidden> writes:
> > Hi Sergio,
> >
> > On Tue, Sep 24, 2019 at 02:44:26PM +0200, 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;
> >> -
> >
> > Are we removing the following checks (ELF magic, flags) because they
> > are superfluous?
> >
> > Should we mention this in the commit message?
>
> Damn, good catch, that's wrong.
>
> The only patches coming from previous iterations are the one factorizing
> the e820 functions and this one, and both are wrong. I'm going to ditch
> them and write whatever it's needed from scratch.
>
> >> - 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 @@
> >> +#ifndef HW_I386_PVH_H
> >> +#define HW_I386_PVH_H
> >> +
> >> +size_t pvh_get_start_addr(void);
> >
> > What about adding "size_t *pvh_start_addr" to the pvh_load_elfboot()?
> > Just an idea, I'm not sure if it is better...
>
> I agree. In fact, given that patch 4/8 extracts some common functions
> from pc.c into x86.c, and load_linux is among these functions, perhaps
> we can avoid creating an independent file and just put the PVH code
> there.
>
> What do you think?
Make sense to me, since it's going to be used by pc and microvm.
Thanks,
Stefano
- [PATCH v4 0/8] Introduce the microvm machine type, Sergio Lopez, 2019/09/24
- [PATCH v4 3/8] hw/virtio: Factorize virtio-mmio headers, Sergio Lopez, 2019/09/24
- [PATCH v4 2/8] hw/i386: Factorize e820 related functions, Sergio Lopez, 2019/09/24
- [PATCH v4 5/8] fw_cfg: add "modify" functions for all types, Sergio Lopez, 2019/09/24
- [PATCH v4 4/8] hw/i386: split PCMachineState deriving X86MachineState from it, Sergio Lopez, 2019/09/24
- [PATCH v4 6/8] roms: add microvm-bios (qboot) as binary and git submodule, Sergio Lopez, 2019/09/24