Re: [patch 12/13] Remove uv bios and efi code related to (now unused) EFI_UV1_MEMMAP

[Ard Biesheuvel]

On Wed, 1 Jul 2020 at 16:18, <steve.wahl@xxxxxxx> wrote:
>
> With UV1 removed, EFI_UV1_MEMMAP is not used.  Remove code used by it
> in arch/x86/platform/uv/bios_uv.c and turn off code in
> arch/x86/platform/efi/efi.c that referenced this code.
>
> Signed-off-by: Steve Wahl <steve.wahl@xxxxxxx>

Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>

> ---
>  arch/x86/platform/efi/efi.c    |    2
>  arch/x86/platform/uv/bios_uv.c |  159 -----------------------------------------
>  2 files changed, 2 insertions(+), 159 deletions(-)
>
> --- linux.orig/arch/x86/platform/uv/bios_uv.c   2020-06-25 16:13:51.765087047 -0500
> +++ linux/arch/x86/platform/uv/bios_uv.c        2020-06-25 16:14:29.821045358 -0500
> @@ -30,17 +30,7 @@ static s64 __uv_bios_call(enum uv_bios_c
>                  */
>                 return BIOS_STATUS_UNIMPLEMENTED;
>
> -       /*
> -        * If EFI_UV1_MEMMAP is set, we need to fall back to using our old EFI
> -        * callback method, which uses efi_call() directly, with the kernel page tables:
> -        */
> -       if (unlikely(efi_enabled(EFI_UV1_MEMMAP))) {
> -               kernel_fpu_begin();
> -               ret = efi_call((void *)__va(tab->function), (u64)which, a1, a2, a3, a4, a5);
> -               kernel_fpu_end();
> -       } else {
> -               ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
> -       }
> +       ret = efi_call_virt_pointer(tab, function, (u64)which, a1, a2, a3, a4, a5);
>
>         return ret;
>  }
> @@ -209,150 +199,3 @@ int uv_bios_init(void)
>         pr_info("UV: UVsystab: Revision:%x\n", uv_systab->revision);
>         return 0;
>  }
> -
> -static void __init early_code_mapping_set_exec(int executable)
> -{
> -       efi_memory_desc_t *md;
> -
> -       if (!(__supported_pte_mask & _PAGE_NX))
> -               return;
> -
> -       /* Make EFI service code area executable */
> -       for_each_efi_memory_desc(md) {
> -               if (md->type == EFI_RUNTIME_SERVICES_CODE ||
> -                   md->type == EFI_BOOT_SERVICES_CODE)
> -                       efi_set_executable(md, executable);
> -       }
> -}
> -
> -void __init efi_uv1_memmap_phys_epilog(pgd_t *save_pgd)
> -{
> -       /*
> -        * After the lock is released, the original page table is restored.
> -        */
> -       int pgd_idx, i;
> -       int nr_pgds;
> -       pgd_t *pgd;
> -       p4d_t *p4d;
> -       pud_t *pud;
> -
> -       nr_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT) , PGDIR_SIZE);
> -
> -       for (pgd_idx = 0; pgd_idx < nr_pgds; pgd_idx++) {
> -               pgd = pgd_offset_k(pgd_idx * PGDIR_SIZE);
> -               set_pgd(pgd_offset_k(pgd_idx * PGDIR_SIZE), save_pgd[pgd_idx]);
> -
> -               if (!pgd_present(*pgd))
> -                       continue;
> -
> -               for (i = 0; i < PTRS_PER_P4D; i++) {
> -                       p4d = p4d_offset(pgd,
> -                                        pgd_idx * PGDIR_SIZE + i * P4D_SIZE);
> -
> -                       if (!p4d_present(*p4d))
> -                               continue;
> -
> -                       pud = (pud_t *)p4d_page_vaddr(*p4d);
> -                       pud_free(&init_mm, pud);
> -               }
> -
> -               p4d = (p4d_t *)pgd_page_vaddr(*pgd);
> -               p4d_free(&init_mm, p4d);
> -       }
> -
> -       kfree(save_pgd);
> -
> -       __flush_tlb_all();
> -       early_code_mapping_set_exec(0);
> -}
> -
> -pgd_t * __init efi_uv1_memmap_phys_prolog(void)
> -{
> -       unsigned long vaddr, addr_pgd, addr_p4d, addr_pud;
> -       pgd_t *save_pgd, *pgd_k, *pgd_efi;
> -       p4d_t *p4d, *p4d_k, *p4d_efi;
> -       pud_t *pud;
> -
> -       int pgd;
> -       int n_pgds, i, j;
> -
> -       early_code_mapping_set_exec(1);
> -
> -       n_pgds = DIV_ROUND_UP((max_pfn << PAGE_SHIFT), PGDIR_SIZE);
> -       save_pgd = kmalloc_array(n_pgds, sizeof(*save_pgd), GFP_KERNEL);
> -       if (!save_pgd)
> -               return NULL;
> -
> -       /*
> -        * Build 1:1 identity mapping for UV1 memmap usage. Note that
> -        * PAGE_OFFSET is PGDIR_SIZE aligned when KASLR is disabled, while
> -        * it is PUD_SIZE ALIGNED with KASLR enabled. So for a given physical
> -        * address X, the pud_index(X) != pud_index(__va(X)), we can only copy
> -        * PUD entry of __va(X) to fill in pud entry of X to build 1:1 mapping.
> -        * This means here we can only reuse the PMD tables of the direct mapping.
> -        */
> -       for (pgd = 0; pgd < n_pgds; pgd++) {
> -               addr_pgd = (unsigned long)(pgd * PGDIR_SIZE);
> -               vaddr = (unsigned long)__va(pgd * PGDIR_SIZE);
> -               pgd_efi = pgd_offset_k(addr_pgd);
> -               save_pgd[pgd] = *pgd_efi;
> -
> -               p4d = p4d_alloc(&init_mm, pgd_efi, addr_pgd);
> -               if (!p4d) {
> -                       pr_err("Failed to allocate p4d table!\n");
> -                       goto out;
> -               }
> -
> -               for (i = 0; i < PTRS_PER_P4D; i++) {
> -                       addr_p4d = addr_pgd + i * P4D_SIZE;
> -                       p4d_efi = p4d + p4d_index(addr_p4d);
> -
> -                       pud = pud_alloc(&init_mm, p4d_efi, addr_p4d);
> -                       if (!pud) {
> -                               pr_err("Failed to allocate pud table!\n");
> -                               goto out;
> -                       }
> -
> -                       for (j = 0; j < PTRS_PER_PUD; j++) {
> -                               addr_pud = addr_p4d + j * PUD_SIZE;
> -
> -                               if (addr_pud > (max_pfn << PAGE_SHIFT))
> -                                       break;
> -
> -                               vaddr = (unsigned long)__va(addr_pud);
> -
> -                               pgd_k = pgd_offset_k(vaddr);
> -                               p4d_k = p4d_offset(pgd_k, vaddr);
> -                               pud[j] = *pud_offset(p4d_k, vaddr);
> -                       }
> -               }
> -               pgd_offset_k(pgd * PGDIR_SIZE)->pgd &= ~_PAGE_NX;
> -       }
> -
> -       __flush_tlb_all();
> -       return save_pgd;
> -out:
> -       efi_uv1_memmap_phys_epilog(save_pgd);
> -       return NULL;
> -}
> -
> -void __iomem *__init efi_ioremap(unsigned long phys_addr, unsigned long size,
> -                                u32 type, u64 attribute)
> -{
> -       unsigned long last_map_pfn;
> -
> -       if (type == EFI_MEMORY_MAPPED_IO)
> -               return ioremap(phys_addr, size);
> -
> -       last_map_pfn = init_memory_mapping(phys_addr, phys_addr + size,
> -                                          PAGE_KERNEL);
> -       if ((last_map_pfn << PAGE_SHIFT) < phys_addr + size) {
> -               unsigned long top = last_map_pfn << PAGE_SHIFT;
> -               efi_ioremap(top, size - (top - phys_addr), type, attribute);
> -       }
> -
> -       if (!(attribute & EFI_MEMORY_WB))
> -               efi_memory_uc((u64)(unsigned long)__va(phys_addr), size);
> -
> -       return (void __iomem *)__va(phys_addr);
> -}
> --- linux.orig/arch/x86/platform/efi/efi.c      2020-06-25 16:13:54.637083901 -0500
> +++ linux/arch/x86/platform/efi/efi.c   2020-06-25 16:15:14.532996386 -0500
> @@ -496,7 +496,7 @@ void __init efi_init(void)
>                 efi_print_memmap();
>  }
>
> -#if defined(CONFIG_X86_32) || defined(CONFIG_X86_UV)
> +#if defined(CONFIG_X86_32)
>
>  void __init efi_set_executable(efi_memory_desc_t *md, bool executable)
>  {
>