Re: [PATCH Part1 v5 26/38] x86/compressed/acpi: move EFI config table access to common code

From: Michael Roth
Date: Wed Aug 25 2021 - 13:15:33 EST

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In reply to: Borislav Petkov: "Re: [PATCH Part1 v5 26/38] x86/compressed/acpi: move EFI config table access to common code"
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On Wed, Aug 25, 2021 at 05:18:20PM +0200, Borislav Petkov wrote:
> On Fri, Aug 20, 2021 at 10:19:21AM -0500, Brijesh Singh wrote:
> > From: Michael Roth <michael.roth@xxxxxxx>
> >
> > Future patches for SEV-SNP-validated CPUID will also require early
> > parsing of the EFI configuration. Move the related code into a set of
> > helpers that can be re-used for that purpose.
> >
> > Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> > ---
> > arch/x86/boot/compressed/Makefile | 1 +
> > arch/x86/boot/compressed/acpi.c | 113 +++++--------------
> > arch/x86/boot/compressed/efi.c | 178 ++++++++++++++++++++++++++++++
> > arch/x86/boot/compressed/misc.h | 43 ++++++++
> > 4 files changed, 251 insertions(+), 84 deletions(-)
> > create mode 100644 arch/x86/boot/compressed/efi.c
>
> Ok, better, but this patch needs splitting. And I have a good idea how:
> in at least three patches:
>
> 1. Add efi_get_system_table() and use it
> 2. Add efi_get_conf_table() and use it
> 3. Add efi_find_vendor_table() and use it
>
> This will facilitate review immensely.

Ok, that makes sense.

>
> Also, here's a diff ontop of what to do also, style-wise.
>
> - change how you look for the preferred vendor table along with commenting what you do
> - shorten variable names so that you don't have so many line breaks.

Thanks for the suggestions, I'll incorporate those changes in the next spin as
well.

>
> Thx.
>
> diff --git a/arch/x86/boot/compressed/acpi.c b/arch/x86/boot/compressed/acpi.c
> index 3a3f997d7210..c22b21e94a95 100644
> --- a/arch/x86/boot/compressed/acpi.c
> +++ b/arch/x86/boot/compressed/acpi.c
> @@ -20,27 +20,29 @@
> */
> struct mem_vector immovable_mem[MAX_NUMNODES*2];
>
> -/*
> - * Search EFI system tables for RSDP. If both ACPI_20_TABLE_GUID and
> - * ACPI_TABLE_GUID are found, take the former, which has more features.
> - */
> static acpi_physical_address
> -__efi_get_rsdp_addr(unsigned long config_table_pa,
> - unsigned int config_table_len, bool efi_64)
> +__efi_get_rsdp_addr(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len, bool efi_64)
> {
> acpi_physical_address rsdp_addr = 0;
> +
> #ifdef CONFIG_EFI
> int ret;
>
> - ret = efi_find_vendor_table(config_table_pa, config_table_len,
> - ACPI_20_TABLE_GUID, efi_64,
> - (unsigned long *)&rsdp_addr);
> - if (ret == -ENOENT)
> - ret = efi_find_vendor_table(config_table_pa, config_table_len,
> - ACPI_TABLE_GUID, efi_64,
> - (unsigned long *)&rsdp_addr);
> + /*
> + * Search EFI system tables for RSDP. Preferred is ACPI_20_TABLE_GUID to
> + * ACPI_TABLE_GUID because it has more features.
> + */
> + ret = efi_find_vendor_table(cfg_tbl_pa, cfg_tbl_len, ACPI_20_TABLE_GUID,
> + efi_64, (unsigned long *)&rsdp_addr);
> + if (!ret)
> + return rsdp_addr;
> +
> + /* No ACPI_20_TABLE_GUID found, fallback to ACPI_TABLE_GUID. */
> + ret = efi_find_vendor_table(cfg_tbl_pa, cfg_tbl_len, ACPI_TABLE_GUID,
> + efi_64, (unsigned long *)&rsdp_addr);
> if (ret)
> debug_putstr("Error getting RSDP address.\n");
> +
> #endif
> return rsdp_addr;
> }
> @@ -100,18 +102,16 @@ static acpi_physical_address kexec_get_rsdp_addr(void) { return 0; }
> static acpi_physical_address efi_get_rsdp_addr(void)
> {
> #ifdef CONFIG_EFI
> - unsigned long config_table_pa = 0;
> - unsigned int config_table_len;
> + unsigned long cfg_tbl_pa = 0;
> + unsigned int cfg_tbl_len;
> bool efi_64;
> int ret;
>
> - ret = efi_get_conf_table(boot_params, &config_table_pa,
> - &config_table_len, &efi_64);
> - if (ret || !config_table_pa)
> + ret = efi_get_conf_table(boot_params, &cfg_tbl_pa, &cfg_tbl_len, &efi_64);
> + if (ret || !cfg_tbl_pa)
> error("EFI config table not found.");
>
> - return __efi_get_rsdp_addr(config_table_pa, config_table_len,
> - efi_64);
> + return __efi_get_rsdp_addr(cfg_tbl_pa, cfg_tbl_len, efi_64);
> #else
> return 0;
> #endif
> diff --git a/arch/x86/boot/compressed/efi.c b/arch/x86/boot/compressed/efi.c
> index 16ff5cb9a1fb..7ed31b943c04 100644
> --- a/arch/x86/boot/compressed/efi.c
> +++ b/arch/x86/boot/compressed/efi.c
> @@ -12,14 +12,14 @@
> #include <asm/efi.h>
>
> /* Get vendor table address/guid from EFI config table at the given index */
> -static int get_vendor_table(void *conf_table, unsigned int idx,
> +static int get_vendor_table(void *cfg_tbl, unsigned int idx,
> unsigned long *vendor_table_pa,
> efi_guid_t *vendor_table_guid,
> bool efi_64)
> {
> if (efi_64) {
> efi_config_table_64_t *table_entry =
> - (efi_config_table_64_t *)conf_table + idx;
> + (efi_config_table_64_t *)cfg_tbl + idx;
>
> if (!IS_ENABLED(CONFIG_X86_64) &&
> table_entry->table >> 32) {
> @@ -32,7 +32,7 @@ static int get_vendor_table(void *conf_table, unsigned int idx,
>
> } else {
> efi_config_table_32_t *table_entry =
> - (efi_config_table_32_t *)conf_table + idx;
> + (efi_config_table_32_t *)cfg_tbl + idx;
>
> *vendor_table_pa = table_entry->table;
> *vendor_table_guid = table_entry->guid;
> @@ -45,27 +45,25 @@ static int get_vendor_table(void *conf_table, unsigned int idx,
> * Given EFI config table, search it for the physical address of the vendor
> * table associated with GUID.
> *
> - * @conf_table: pointer to EFI configuration table
> - * @conf_table_len: number of entries in EFI configuration table
> + * @cfg_tbl: pointer to EFI configuration table
> + * @cfg_tbl_len: number of entries in EFI configuration table
> * @guid: GUID of vendor table
> * @efi_64: true if using 64-bit EFI
> * @vendor_table_pa: location to store physical address of vendor table
> *
> * Returns 0 on success. On error, return params are left unchanged.
> */
> -int
> -efi_find_vendor_table(unsigned long conf_table_pa, unsigned int conf_table_len,
> - efi_guid_t guid, bool efi_64,
> - unsigned long *vendor_table_pa)
> +int efi_find_vendor_table(unsigned long cfg_tbl_pa, unsigned int cfg_tbl_len,
> + efi_guid_t guid, bool efi_64, unsigned long *vendor_table_pa)
> {
> unsigned int i;
>
> - for (i = 0; i < conf_table_len; i++) {
> + for (i = 0; i < cfg_tbl_len; i++) {
> unsigned long vendor_table_pa_tmp;
> efi_guid_t vendor_table_guid;
> int ret;
>
> - if (get_vendor_table((void *)conf_table_pa, i,
> + if (get_vendor_table((void *)cfg_tbl_pa, i,
> &vendor_table_pa_tmp,
> &vendor_table_guid, efi_64))
> return -EINVAL;
> @@ -88,9 +86,8 @@ efi_find_vendor_table(unsigned long conf_table_pa, unsigned int conf_table_len,
> *
> * Returns 0 on success. On error, return params are left unchanged.
> */
> -int
> -efi_get_system_table(struct boot_params *boot_params,
> - unsigned long *sys_table_pa, bool *is_efi_64)
> +int efi_get_system_table(struct boot_params *boot_params, unsigned long *sys_table_pa,
> + bool *is_efi_64)
> {
> unsigned long sys_table;
> struct efi_info *ei;
> @@ -137,22 +134,19 @@ efi_get_system_table(struct boot_params *boot_params,
> * address EFI configuration table.
> *
> * @boot_params: pointer to boot_params
> - * @conf_table_pa: location to store physical address of config table
> - * @conf_table_len: location to store number of config table entries
> + * @cfg_tbl_pa: location to store physical address of config table
> + * @cfg_tbl_len: location to store number of config table entries
> * @is_efi_64: location to store whether using 64-bit EFI or not
> *
> * Returns 0 on success. On error, return params are left unchanged.
> */
> -int
> -efi_get_conf_table(struct boot_params *boot_params,
> - unsigned long *conf_table_pa,
> - unsigned int *conf_table_len,
> - bool *is_efi_64)
> +int efi_get_conf_table(struct boot_params *boot_params, unsigned long *cfg_tbl_pa,
> + unsigned int *cfg_tbl_len, bool *is_efi_64)
> {
> unsigned long sys_table_pa = 0;
> int ret;
>
> - if (!conf_table_pa || !conf_table_len || !is_efi_64)
> + if (!cfg_tbl_pa || !cfg_tbl_len || !is_efi_64)
> return -EINVAL;
>
> ret = efi_get_system_table(boot_params, &sys_table_pa, is_efi_64);
> @@ -164,14 +158,14 @@ efi_get_conf_table(struct boot_params *boot_params,
> efi_system_table_64_t *stbl =
> (efi_system_table_64_t *)sys_table_pa;
>
> - *conf_table_pa = stbl->tables;
> - *conf_table_len = stbl->nr_tables;
> + *cfg_tbl_pa = stbl->tables;
> + *cfg_tbl_len = stbl->nr_tables;
> } else {
> efi_system_table_32_t *stbl =
> (efi_system_table_32_t *)sys_table_pa;
>
> - *conf_table_pa = stbl->tables;
> - *conf_table_len = stbl->nr_tables;
> + *cfg_tbl_pa = stbl->tables;
> + *cfg_tbl_len = stbl->nr_tables;
> }
>
> return 0;
>
> --
> Regards/Gruss,
> Boris.
>
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpeople.kernel.org%2Ftglx%2Fnotes-about-netiquette&data=04%7C01%7CMichael.Roth%40amd.com%7Cb4091a3e85cd463b1cb608d967db81ec%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637655014764920013%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=rvxyc%2FAURXMBWX5lkUHQoM1a%2FlGt4ZtcfGCJZ1TjIQU%3D&reserved=0

Next message: Catalin Marinas: "Re: [BUG 5.14] arm64/mm: dma memory mapping fails (in some cases)"
Previous message: Michael Roth: "Re: [PATCH Part1 v5 23/38] x86/head/64: set up a startup %gs for stack protector"
In reply to: Borislav Petkov: "Re: [PATCH Part1 v5 26/38] x86/compressed/acpi: move EFI config table access to common code"
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