Re: [PATCH 1/4] efi/x86: make efi_memmap_reserve only insert into boot mem areas

Ard Biesheuvel
2017-01-12T16:16:03Z

Hello Dave,

On 12 January 2017 at 09:41, Dave Young <dyoung@redhat.com> wrote:
> There are memory ranges like below when I testing early efi_mem_reserve:
>
> efi: mem62: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
> efi: mem63: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
> efi: mem64: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
> efi: mem65: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
> efi: mem66: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
> efi: mem67: [Reserved | | | | | | | | | | | | ] range=[0x0000000000000000-0xffffffffffffffff] (0MB)
>

Did you spot Peter's patch to prune invalid memmap entries?

https://git.kernel.org/cgit/linux/kernel/git/efi/efi.git/commit/?h=next&id=b2a91a35445229

I would expect this patch to no longer be necessary with that in place, no?

> So efi_memmap_insert will run into inserting same region multiple times,
> also because efi_memmap_insert does not consider the duplicate ranges it will
> cause memmap buffer overflow due to the size is pre-calculated, and kernel boot
> fail with a panic. We did not detect such issue because current users of
> efi_mem_insert do it very late after switching to virtual mode, at that time
> the new cooked efi.memmap contains only runtime needed memory ranges.
>
> efi_mem_reserve cares only about boot services regions and maybe loader areas.
> So add a new argument to efi_memmap_insert for this purpose.
>
> Later patches depend on this one for moving bgrt reservation to early code.
>
> Signed-off-by: Dave Young <dyoung@redhat.com>
> ---
> arch/x86/platform/efi/quirks.c | 2 +-
> drivers/firmware/efi/fake_mem.c | 3 ++-
> drivers/firmware/efi/memmap.c | 8 +++++++-
> include/linux/efi.h | 4 ++--
> 4 files changed, 12 insertions(+), 5 deletions(-)
>
> --- linux-x86.orig/drivers/firmware/efi/memmap.c
> +++ linux-x86/drivers/firmware/efi/memmap.c
> @@ -213,7 +213,7 @@ int __init efi_memmap_split_count(efi_me
> * to see how large @buf needs to be.
> */
> void __init efi_memmap_insert(struct efi_memory_map *old_memmap, void *buf,
> - struct efi_mem_range *mem)
> + struct efi_mem_range *mem, bool boot_only)
> {
> u64 m_start, m_end, m_attr;
> efi_memory_desc_t *md;
> @@ -246,6 +246,12 @@ void __init efi_memmap_insert(struct efi
> start = md->phys_addr;
> end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
>
> + if (boot_only && !(md->type == EFI_LOADER_DATA ||
> + md->type == EFI_LOADER_CODE ||
> + md->type == EFI_BOOT_SERVICES_CODE ||
> + md->type == EFI_BOOT_SERVICES_DATA))
> + continue;
> +
> if (m_start <= start && end <= m_end)
> md->attribute |= m_attr;
>
> --- linux-x86.orig/arch/x86/platform/efi/quirks.c
> +++ linux-x86/arch/x86/platform/efi/quirks.c
> @@ -226,7 +226,7 @@ void __init efi_arch_mem_reserve(phys_ad
> return;
> }
>
> - efi_memmap_insert(&efi.memmap, new, &mr);
> + efi_memmap_insert(&efi.memmap, new, &mr, true);
> early_memunmap(new, new_size);
>
> efi_memmap_install(new_phys, num_entries);
> --- linux-x86.orig/drivers/firmware/efi/fake_mem.c
> +++ linux-x86/drivers/firmware/efi/fake_mem.c
> @@ -85,7 +85,8 @@ void __init efi_fake_memmap(void)
> }
>
> for (i = 0; i < nr_fake_mem; i++)
> - efi_memmap_insert(&efi.memmap, new_memmap, &fake_mems[i]);
> + efi_memmap_insert(&efi.memmap, new_memmap, &fake_mems[i],
> + false);
>
> /* swap into new EFI memmap */
> early_memunmap(new_memmap, efi.memmap.desc_size * new_nr_map);
> --- linux-x86.orig/include/linux/efi.h
> +++ linux-x86/include/linux/efi.h
> @@ -957,8 +957,8 @@ extern int __init efi_memmap_install(phy
> extern int __init efi_memmap_split_count(efi_memory_desc_t *md,
> struct range *range);
> extern void __init efi_memmap_insert(struct efi_memory_map *old_memmap,
> - void *buf, struct efi_mem_range *mem);
> -
> + void *buf, struct efi_mem_range *mem,
> + bool boot_only);
> extern int efi_config_init(efi_config_table_type_t *arch_tables);
> #ifdef CONFIG_EFI_ESRT
> extern void __init efi_esrt_init(void);
>
>