Hi Bhupesh, -----Original Message----- > ARMv8.2-LPA architecture extension (if available on underlying hardware) > can support 52-bit physical addresses, while the kernel virtual > addresses remain 48-bit. > > This patch is in accordance with ARMv8 Architecture Reference Manual > version D.a > > Make sure that we read the 52-bit PA address capability from > 'MAX_PHYSMEM_BITS' variable (if available in vmcoreinfo) and > accordingly change the pte_to_phy() mask values and also traverse > the page-table walk accordingly. > > Also make sure that it works well for the existing 48-bit PA address > platforms and also on environments which use newer kernels with 52-bit > PA support but hardware which is not ARM8.2-LPA compliant. > > I have sent a kernel patch upstream to add 'MAX_PHYSMEM_BITS' to > vmcoreinfo for arm64 (see [0]). > > [0]. http://lists.infradead.org/pipermail/kexec/2019-February/022411.html > > Signed-off-by: Bhupesh Sharma <bhsharma@xxxxxxxxxx> This patch looks good to me. For two slight things below, I will remove them when merging. > +/* > + * Size mapped by an entry at level n ( 0 <= n <= 3) > + * We map (PAGE_SHIFT - 3) at all translation levels and PAGE_SHIFT bits > + * in the final page. The maximum number of translation levels supported by > + * the architecture is 4. Hence, starting at at level n, we have further > + * ((4 - n) - 1) levels of translation excluding the offset within the page. > + * So, the total number of bits mapped by an entry at level n is : > + * > + * ((4 - n) - 1) * (PAGE_SHIFT - 3) + PAGE_SHIFT > + * > + * Rearranging it a bit we get : > + * (4 - n) * (PAGE_SHIFT - 3) + 3 > + */ Will remove this comment. > +#define pmd_offset_pgtbl_lvl_2(dir, vaddr) ((pmd_t *)dir) > +#define pmd_offset_pgtbl_lvl_3(dir, vaddr) (pud_page_paddr((*(dir))) + pmd_index(vaddr) * sizeof(pmd_t)) Will remove these two macros not in use. And, as I said on another thread, I'm thinking to merge the following patch after your patch 1/2, it tested OK with 48-bit and 52-bit PA without NUMBER(MAX_PHYSMEM_BITS) in vmcoreinfo. Do you think of any case that this will not work well? diff --git a/arch/arm64.c b/arch/arm64.c index 29247a7..c7e60e0 100644 --- a/arch/arm64.c +++ b/arch/arm64.c @@ -127,6 +127,9 @@ typedef unsigned long pgdval_t; */ #define SECTIONS_SIZE_BITS 30 +#define _MAX_PHYSMEM_BITS_48 48 +#define _MAX_PHYSMEM_BITS_52 52 + /* * Hardware page table definitions. * @@ -402,17 +405,27 @@ get_stext_symbol(void) return(found ? kallsym : FALSE); } +static int +set_max_physmem_bits_arm64(void) +{ + long array_len = ARRAY_LENGTH(mem_section); + + info->max_physmem_bits = _MAX_PHYSMEM_BITS_48; + if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) + || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) + return TRUE; + + info->max_physmem_bits = _MAX_PHYSMEM_BITS_52; + if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) + || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) + return TRUE; + + return FALSE; +} + int get_machdep_info_arm64(void) { - /* Determine if the PA address range is 52-bits: ARMv8.2-LPA */ - if (NUMBER(MAX_PHYSMEM_BITS) != NOT_FOUND_NUMBER) { - info->max_physmem_bits = NUMBER(MAX_PHYSMEM_BITS); - if (info->max_physmem_bits == 52) - lpa_52_bit_support_available = 1; - } else - info->max_physmem_bits = 48; - /* Check if va_bits is still not initialized. If still 0, call * get_versiondep_info() to initialize the same. */ @@ -428,9 +441,24 @@ get_machdep_info_arm64(void) info->section_size_bits = SECTIONS_SIZE_BITS; DEBUG_MSG("kimage_voffset : %lx\n", kimage_voffset); - DEBUG_MSG("max_physmem_bits : %ld\n", info->max_physmem_bits); DEBUG_MSG("section_size_bits: %ld\n", info->section_size_bits); + /* Determine if the PA address range is 52-bits: ARMv8.2-LPA */ + if (NUMBER(MAX_PHYSMEM_BITS) != NOT_FOUND_NUMBER) { + info->max_physmem_bits = NUMBER(MAX_PHYSMEM_BITS); + DEBUG_MSG("max_physmem_bits : %ld (vmcoreinfo)\n", + info->max_physmem_bits); + } else if (set_max_physmem_bits_arm64()) { + DEBUG_MSG("max_physmem_bits : %ld (detected)\n", + info->max_physmem_bits); + } else { + ERRMSG("Can't determine max_physmem_bits value\n"); + return FALSE; + } + + if (info->max_physmem_bits == 52) + lpa_52_bit_support_available = 1; + return TRUE; } Thanks, Kazu _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
