Re: [PATCH v15 5/6] x86/boot: Parse SRAT address from RSDP and store immovable memory

[Kairui Song]

On Mon, Jan 7, 2019 at 11:24 AM Chao Fan <fanc.fnst@xxxxxxxxxxxxxx> wrote:
>
> +
> +/* Determine RSDP, based on acpi_os_get_root_pointer(). */
> +static acpi_physical_address get_rsdp_addr(void)
> +{
> +       acpi_physical_address pa;
> +
> +       pa = get_acpi_rsdp();
> +
> +       if (!pa)
> +               pa = efi_get_rsdp_addr();
> +
> +       if (!pa)
> +               pa = bios_get_rsdp_addr();
> +
> +       return pa;
> +}

acpi_rsdp might be provided by boot_params.acpi_rsdp_addr too,
it's introduced in ae7e1238e68f2a for Xen PVH guest and later move to
boot_params in e6e094e053af,
kexec could use it to pass RSDP to second kernel as well. Please check
it as well make sure it always works.

> +
> +/* Compute SRAT address from RSDP. */
> +static struct acpi_table_header *get_acpi_srat_table(void)
> +{
> +       acpi_physical_address acpi_table;
> +       acpi_physical_address root_table;
> +       struct acpi_table_header *header;
> +       struct acpi_table_rsdp *rsdp;
> +       u32 num_entries;
> +       char arg[10];
> +       u8 *entry;
> +       u32 size;
> +       u32 len;
> +
> +       rsdp = (struct acpi_table_rsdp *)(long)get_rsdp_addr();
> +       if (!rsdp)
> +               return NULL;
> +
> +       /* Get RSDT or XSDT from RSDP. */
> +       if (!(cmdline_find_option("acpi", arg, sizeof(arg)) == 4 &&
> +           !strncmp(arg, "rsdt", 4)) &&
> +           rsdp->xsdt_physical_address &&
> +           rsdp->revision > 1) {
> +               root_table = rsdp->xsdt_physical_address;
> +               size = ACPI_XSDT_ENTRY_SIZE;
> +       } else {
> +               root_table = rsdp->rsdt_physical_address;
> +               size = ACPI_RSDT_ENTRY_SIZE;
> +       }
> +
> +       /* Get ACPI root table from RSDT or XSDT.*/
> +       if (!root_table)
> +               return NULL;
> +       header = (struct acpi_table_header *)(long)root_table;
> +
> +       len = header->length;
> +       if (len < sizeof(struct acpi_table_header) + size)
> +               return NULL;
> +
> +       num_entries = (u32)((len - sizeof(struct acpi_table_header)) / size);
> +       entry = ACPI_ADD_PTR(u8, header, sizeof(struct acpi_table_header));
> +
> +       while (num_entries--) {
> +               u64 address64;
> +
> +               if (size == ACPI_RSDT_ENTRY_SIZE)
> +                       acpi_table =  *ACPI_CAST_PTR(u32, entry);
> +               else {
> +                       address64 = *(u64 *)entry;
> +                       acpi_table = address64;
> +               }
> +
> +               if (acpi_table) {
> +                       header = (struct acpi_table_header *)(long)acpi_table;
> +
> +                       if (ACPI_COMPARE_NAME(header->signature, ACPI_SIG_SRAT))
> +                               return header;
> +               }
> +               entry += size;
> +       }
> +       return NULL;
> +}
> +
> +/*
> + * According to ACPI table, filter the immovable memory regions
> + * and store them in immovable_mem[].
> + */
> +void get_immovable_mem(void)
> +{
> +       struct acpi_table_header *table_header;
> +       struct acpi_subtable_header *table;
> +       struct acpi_srat_mem_affinity *ma;
> +       char arg[MAX_ACPI_ARG_LENGTH];
> +       unsigned long table_end;
> +       int i = 0;
> +
> +       if (cmdline_find_option("acpi", arg, sizeof(arg)) == 3 &&
> +           !strncmp(arg, "off", 3))
> +               return;
> +
> +       table_header = get_acpi_srat_table();
> +       if (!table_header)
> +               return;
> +
> +       table_end = (unsigned long)table_header + table_header->length;
> +       table = (struct acpi_subtable_header *)
> +               ((unsigned long)table_header + sizeof(struct acpi_table_srat));
> +
> +       while (((unsigned long)table) +
> +                      sizeof(struct acpi_subtable_header) < table_end) {
> +               if (table->type == ACPI_SRAT_TYPE_MEMORY_AFFINITY) {
> +                       ma = (struct acpi_srat_mem_affinity *)table;
> +                       if (!(ma->flags & ACPI_SRAT_MEM_HOT_PLUGGABLE)) {
> +                               immovable_mem[i].start = ma->base_address;
> +                               immovable_mem[i].size = ma->length;
> +                               i++;
> +                       }
> +
> +                       if (i >= MAX_NUMNODES*2) {
> +                               debug_putstr("Too many immovable memory regions, aborting.\n");
> +                               return;
> +                       }
> +               }
> +               table = (struct acpi_subtable_header *)
> +                       ((unsigned long)table + table->length);
> +       }
> +       num_immovable_mem = i;
> +}
> diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
> index 9ed9709d9947..b251572e77af 100644
> --- a/arch/x86/boot/compressed/kaslr.c
> +++ b/arch/x86/boot/compressed/kaslr.c
> @@ -87,10 +87,6 @@ static unsigned long get_boot_seed(void)
>  #define KASLR_COMPRESSED_BOOT
>  #include "../../lib/kaslr.c"
>
> -struct mem_vector {
> -       unsigned long long start;
> -       unsigned long long size;
> -};
>
>  /* Only supporting at most 4 unusable memmap regions with kaslr */
>  #define MAX_MEMMAP_REGIONS     4
> diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h
> index a1d5918765f3..b49748366a5b 100644
> --- a/arch/x86/boot/compressed/misc.h
> +++ b/arch/x86/boot/compressed/misc.h
> @@ -77,6 +77,11 @@ void choose_random_location(unsigned long input,
>                             unsigned long *output,
>                             unsigned long output_size,
>                             unsigned long *virt_addr);
> +struct mem_vector {
> +       unsigned long long start;
> +       unsigned long long size;
> +};
> +
>  /* cpuflags.c */
>  bool has_cpuflag(int flag);
>  #else
> @@ -116,3 +121,17 @@ static inline void console_init(void)
>  void set_sev_encryption_mask(void);
>
>  #endif
> +
> +/* acpi.c */
> +#ifdef CONFIG_RANDOMIZE_BASE
> +/* Amount of immovable memory regions */
> +int num_immovable_mem;
> +#endif
> +
> +#ifdef CONFIG_EARLY_SRAT_PARSE
> +void get_immovable_mem(void);
> +#else
> +static void get_immovable_mem(void)
> +{
> +}
> +#endif
> --
> 2.20.1
>
>
>


-- 
Best Regards,
Kairui Song