Re: [GRUB2 PATCH v4 3/4 - FOR REVIEW ONLY] multiboot2: Do not pass memory maps to image if EFI boot services are enabled

From: "Vladimir 'phcoder' Serbinenko" <phcoder@gmail.com>
To: Andrei Borzenkov <arvidjaar@gmail.com>,
	Daniel Kiper <daniel.kiper@oracle.com>
Cc: "jgross@suse.com" <jgross@suse.com>,
	"eric.snowberg@oracle.com" <eric.snowberg@oracle.com>,
	"grub-devel@gnu.org" <grub-devel@gnu.org>,
	"andrew.cooper3@citrix.com" <andrew.cooper3@citrix.com>,
	"cardoe@cardoe.com" <cardoe@cardoe.com>,
	"pgnet.dev@gmail.com" <pgnet.dev@gmail.com>,
	"roy.franz@linaro.org" <roy.franz@linaro.org>,
	"ning.sun@intel.com" <ning.sun@intel.com>,
	"david.vrabel@citrix.com" <david.vrabel@citrix.com>,
	"jbeulich@suse.com" <jbeulich@suse.com>,
	"stefano.stabellini@eu.citrix.com"
	<stefano.stabellini@eu.citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	"qiaowei.ren@intel.com" <qiaowei.ren@intel.com>,
	"richard.l.maliszewski@intel.com"
	<richard.l.maliszewski@intel.com>,
	"gang.wei@intel.com" <gang.wei@intel.com>,
	"fu.wei@linaro.org" <fu.wei@linaro.org>,
	"seth.goldberg@oracle.com" <seth.goldberg@oracle.com>
Subject: Re: [GRUB2 PATCH v4 3/4 - FOR REVIEW ONLY] multiboot2: Do not pass memory maps to image if EFI boot services are enabled
Date: Tue, 15 Mar 2016 18:10:48 +0000	[thread overview]
Message-ID: <CAEaD8JMgHphk31781sFpZVcT5+Q+Sj1LGpNfvhr3cbT=+sU1Lg@mail.gmail.com> (raw)
In-Reply-To: <56E84F10.5080804@gmail.com>

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Le mar. 15 mars 2016 19:06, Andrei Borzenkov <arvidjaar@gmail.com> a écrit :

> 15.03.2016 19:07, Vladimir 'phcoder' Serbinenko пишет:
> > Looks good. Let's give a day for others to comment. Is the second email
> the
> > version for commit?
> >
> > On Tuesday, March 15, 2016, Daniel Kiper <daniel.kiper@oracle.com>
> wrote:
> >
> >> Do not pass memory maps to image if it asked for EFI boot services.
> >> Main reason for not providing maps is because they will likely be
> >> invalid. We do a few allocations after filling them, e.g. for relocator
> >> needs. Usually we do not care as we would already finish boot services.
> >> If we keep boot services then it is easier to not provide maps. However,
> >> if image needs memory maps and they are not provided by bootloader then
> >> it should get them itself just before ExitBootServices() call.
> >>
>
> Are there any existing users of it that rely on memory map provided by
> bootloader? What if image explicitly requested non-optional memory map?
> According to multiboot specification it is valid and bootloader must
> either provide requested information or fail load.
>
I think you have a point. @Daniel, is current behavior a problem for you?
Don't you just ignore the memory map in this case?

>
> >> Signed-off-by: Daniel Kiper <daniel.kiper@oracle.com <javascript:;>>
> >> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com
> <javascript:;>>
> >> ---
> >> v3 - suggestions/fixes:
> >>    - improve commit message
> >>      (suggested by Konrad Rzeszutek Wilk and Vladimir 'phcoder'
> >> Serbinenko).
> >> ---
> >>  grub-core/loader/multiboot_mbi2.c |   71
> >> ++++++++++++++++++-------------------
> >>  1 file changed, 35 insertions(+), 36 deletions(-)
> >>
> >> diff --git a/grub-core/loader/multiboot_mbi2.c
> >> b/grub-core/loader/multiboot_mbi2.c
> >> index 6c04402..ad1553b 100644
> >> --- a/grub-core/loader/multiboot_mbi2.c
> >> +++ b/grub-core/loader/multiboot_mbi2.c
> >> @@ -390,7 +390,7 @@ static grub_size_t
> >>  grub_multiboot_get_mbi_size (void)
> >>  {
> >>  #ifdef GRUB_MACHINE_EFI
> >> -  if (!efi_mmap_size)
> >> +  if (!keep_bs && !efi_mmap_size)
> >>      find_efi_mmap_size ();
> >>  #endif
> >>    return 2 * sizeof (grub_uint32_t) + sizeof (struct multiboot_tag)
> >> @@ -755,12 +755,13 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
> >>        }
> >>    }
> >>
> >> -  {
> >> -    struct multiboot_tag_mmap *tag = (struct multiboot_tag_mmap *)
> >> ptrorig;
> >> -    grub_fill_multiboot_mmap (tag);
> >> -    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> -      / sizeof (grub_properly_aligned_t);
> >> -  }
> >> +  if (!keep_bs)
> >> +    {
> >> +      struct multiboot_tag_mmap *tag = (struct multiboot_tag_mmap *)
> >> ptrorig;
> >> +      grub_fill_multiboot_mmap (tag);
> >> +      ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> +       / sizeof (grub_properly_aligned_t);
> >> +    }
> >>
> >>    {
> >>      struct multiboot_tag_elf_sections *tag
> >> @@ -776,18 +777,19 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
> >>        / sizeof (grub_properly_aligned_t);
> >>    }
> >>
> >> -  {
> >> -    struct multiboot_tag_basic_meminfo *tag
> >> -      = (struct multiboot_tag_basic_meminfo *) ptrorig;
> >> -    tag->type = MULTIBOOT_TAG_TYPE_BASIC_MEMINFO;
> >> -    tag->size = sizeof (struct multiboot_tag_basic_meminfo);
> >> +  if (!keep_bs)
> >> +    {
> >> +      struct multiboot_tag_basic_meminfo *tag
> >> +       = (struct multiboot_tag_basic_meminfo *) ptrorig;
> >> +      tag->type = MULTIBOOT_TAG_TYPE_BASIC_MEMINFO;
> >> +      tag->size = sizeof (struct multiboot_tag_basic_meminfo);
> >>
> >> -    /* Convert from bytes to kilobytes.  */
> >> -    tag->mem_lower = grub_mmap_get_lower () / 1024;
> >> -    tag->mem_upper = grub_mmap_get_upper () / 1024;
> >> -    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> -       / sizeof (grub_properly_aligned_t);
> >> -  }
> >> +      /* Convert from bytes to kilobytes.  */
> >> +      tag->mem_lower = grub_mmap_get_lower () / 1024;
> >> +      tag->mem_upper = grub_mmap_get_upper () / 1024;
> >> +      ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> +       / sizeof (grub_properly_aligned_t);
> >> +    }
> >>
> >>    {
> >>      struct grub_net_network_level_interface *net;
> >> @@ -886,27 +888,24 @@ grub_multiboot_make_mbi (grub_uint32_t *target)
> >>      grub_efi_uintn_t efi_desc_size;
> >>      grub_efi_uint32_t efi_desc_version;
> >>
> >> -    tag->type = MULTIBOOT_TAG_TYPE_EFI_MMAP;
> >> -    tag->size = sizeof (*tag) + efi_mmap_size;
> >> -
> >>      if (!keep_bs)
> >> -      err = grub_efi_finish_boot_services (&efi_mmap_size,
> tag->efi_mmap,
> >> NULL,
> >> -                                          &efi_desc_size,
> >> &efi_desc_version);
> >> -    else
> >>        {
> >> -       if (grub_efi_get_memory_map (&efi_mmap_size, (void *)
> >> tag->efi_mmap,
> >> -                                    NULL,
> >> -                                    &efi_desc_size, &efi_desc_version)
> <=
> >> 0)
> >> -         err = grub_error (GRUB_ERR_IO, "couldn't retrieve memory
> map");
> >> +       tag->type = MULTIBOOT_TAG_TYPE_EFI_MMAP;
> >> +       tag->size = sizeof (*tag) + efi_mmap_size;
> >> +
> >> +       err = grub_efi_finish_boot_services (&efi_mmap_size,
> >> tag->efi_mmap, NULL,
> >> +                                            &efi_desc_size,
> >> &efi_desc_version);
> >> +
> >> +       if (err)
> >> +         return err;
> >> +
> >> +       tag->descr_size = efi_desc_size;
> >> +       tag->descr_vers = efi_desc_version;
> >> +       tag->size = sizeof (*tag) + efi_mmap_size;
> >> +
> >> +       ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> +         / sizeof (grub_properly_aligned_t);
> >>        }
> >> -    if (err)
> >> -      return err;
> >> -    tag->descr_size = efi_desc_size;
> >> -    tag->descr_vers = efi_desc_version;
> >> -    tag->size = sizeof (*tag) + efi_mmap_size;
> >> -
> >> -    ptrorig += ALIGN_UP (tag->size, MULTIBOOT_TAG_ALIGN)
> >> -      / sizeof (grub_properly_aligned_t);
> >>    }
> >>
> >>    if (keep_bs)
> >> --
> >> 1.7.10.4
> >>
> >>
> >
>
>

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