Re: [PATCHv5 06/12] x86/boot/compressed: Handle unaccepted memory

Borislav Petkov
2022-05-03T14:13:07Z

On Mon, Apr 25, 2022 at 06:39:28AM +0300, Kirill A. Shutemov wrote:
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 411b268bc0a2..59db90626042 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -725,10 +725,20 @@ process_efi_entries(unsigned long minimum, unsigned long image_size)
> * but in practice there's firmware where using that memory leads
> * to crashes.
> *
> - * Only EFI_CONVENTIONAL_MEMORY is guaranteed to be free.
> + * Only EFI_CONVENTIONAL_MEMORY and EFI_UNACCEPTED_MEMORY (if
> + * supported) are guaranteed to be free.
> */
> - if (md->type != EFI_CONVENTIONAL_MEMORY)
> +
> + switch (md->type) {
> + case EFI_CONVENTIONAL_MEMORY:
> + break;
> + case EFI_UNACCEPTED_MEMORY:
> + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY))
> + break;
> continue;
> + default:
> + continue;
> + }

Is there any special reason for this to be a switch-case or can it
simply be a compound conditional if (bla...) ?

> @@ -66,3 +69,21 @@ void process_unaccepted_memory(struct boot_params *params, u64 start, u64 end)
> bitmap_set((unsigned long *)params->unaccepted_memory,
> start / PMD_SIZE, (end - start) / PMD_SIZE);
> }
> +
> +void accept_memory(phys_addr_t start, phys_addr_t end)
> +{
> + unsigned long range_start, range_end;
> + unsigned long *unaccepted_memory;

Please shorten that name so that you don't have to break the lines below.

> + unsigned long bitmap_size;
> +
> + unaccepted_memory = (unsigned long *)boot_params->unaccepted_memory;
> + range_start = start / PMD_SIZE;
> + bitmap_size = DIV_ROUND_UP(end, PMD_SIZE);
> +
> + for_each_set_bitrange_from(range_start, range_end,
> + unaccepted_memory, bitmap_size) {
> + __accept_memory(range_start * PMD_SIZE, range_end * PMD_SIZE);
> + bitmap_clear(unaccepted_memory,
> + range_start, range_end - range_start);
> + }
> +}
> diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
> index fa8969fad011..285b37e28074 100644
> --- a/arch/x86/boot/compressed/misc.c
> +++ b/arch/x86/boot/compressed/misc.c
> @@ -18,6 +18,7 @@
> #include "../string.h"
> #include "../voffset.h"
> #include <asm/bootparam_utils.h>
> +#include <asm/unaccepted_memory.h>
>
> /*
> * WARNING!!
> @@ -451,6 +452,14 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
> #endif
>
> debug_putstr("\nDecompressing Linux... ");
> +
> +#ifdef CONFIG_UNACCEPTED_MEMORY

IS_ENABLED() perhaps?

> + if (boot_params->unaccepted_memory) {

Also, that ->unaccepted_memory will be set only when
ACONFIG_UNACCEPTED_MEMORY is set, FAICT.

--
Regards/Gruss,
Boris.