Re: [PATCHv5 05/12] efi/x86: Implement support for unaccepted memory

Borislav Petkov
2022-04-29T10:53:47Z

On Mon, Apr 25, 2022 at 06:39:27AM +0300, Kirill A. Shutemov wrote:
> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> index 5401985901f5..f9b88174209e 100644
> --- a/drivers/firmware/efi/libstub/x86-stub.c
> +++ b/drivers/firmware/efi/libstub/x86-stub.c
> @@ -15,6 +15,7 @@
> #include <asm/setup.h>
> #include <asm/desc.h>
> #include <asm/boot.h>
> +#include <asm/unaccepted_memory.h>
>
> #include "efistub.h"
>
> @@ -504,6 +505,17 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s
> e820_type = E820_TYPE_PMEM;
> break;
>
> + case EFI_UNACCEPTED_MEMORY:
> + if (!IS_ENABLED(CONFIG_UNACCEPTED_MEMORY)) {
> + efi_warn_once("The system has unaccepted memory,"
> + " but kernel does not support it\n");
> + efi_warn_once("Consider enabling UNACCEPTED_MEMORY\n");

CONFIG_UNACCEPTED_MEMORY

> + continue;
> + }
> + e820_type = E820_TYPE_RAM;
> + process_unaccepted_memory(params, d->phys_addr,
> + d->phys_addr + PAGE_SIZE * d->num_pages);

Align arguments on the opening brace.

> + break;
> default:
> continue;
> }
> @@ -568,6 +580,59 @@ static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext,
> return status;
> }
>
> +static efi_status_t allocate_unaccepted_memory(struct boot_params *params,
> + __u32 nr_desc,
> + struct efi_boot_memmap *map)
> +{
> + unsigned long *mem = NULL;
> + u64 size, max_addr = 0;
> + efi_status_t status;
> + bool found = false;
> + int i;
> +
> + /* Check if there's any unaccepted memory and find the max address */
> + for (i = 0; i < nr_desc; i++) {
> + efi_memory_desc_t *d;
> +
> + d = efi_early_memdesc_ptr(*map->map, *map->desc_size, i);
> + if (d->type == EFI_UNACCEPTED_MEMORY)
> + found = true;
> + if (d->phys_addr + d->num_pages * PAGE_SIZE > max_addr)
> + max_addr = d->phys_addr + d->num_pages * PAGE_SIZE;
> + }
> +
> + if (!found) {
> + params->unaccepted_memory = 0;
> + return EFI_SUCCESS;
> + }
> +
> + /*
> + * If unaccepted memory is present allocate a bitmap to track what
> + * memory has to be accepted before access.
> + *
> + * One bit in the bitmap represents 2MiB in the address space:
> + * A 4k bitmap can track 64GiB of physical address space.
> + *
> + * In the worst case scenario -- a huge hole in the middle of the
> + * address space -- It needs 256MiB to handle 4PiB of the address
> + * space.
> + *
> + * TODO: handle situation if params->unaccepted_memory has already set.

"... is already set."

And when is that TODO taken care of? Later patch or patchset?

Thx.

--
Regards/Gruss,
Boris.