[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v3 9/9] xen/ppc: mm-radix: Allocate all paging structures at runtime
On 14.03.2024 23:15, Shawn Anastasio wrote: > --- a/xen/arch/ppc/mm-radix.c > +++ b/xen/arch/ppc/mm-radix.c > @@ -21,69 +21,101 @@ void enable_mmu(void); > #define radix_dprintk(...) > #endif > > -#define INITIAL_LVL1_PD_COUNT 1 > -#define INITIAL_LVL2_LVL3_PD_COUNT 2 > -#define INITIAL_LVL4_PT_COUNT 256 > - > -static size_t __initdata initial_lvl1_pd_pool_used; > -static struct lvl1_pd initial_lvl1_pd_pool[INITIAL_LVL1_PD_COUNT]; > - > -static size_t __initdata initial_lvl2_lvl3_pd_pool_used; > -static struct lvl2_pd initial_lvl2_lvl3_pd_pool[INITIAL_LVL2_LVL3_PD_COUNT]; > - > -static size_t __initdata initial_lvl4_pt_pool_used; > -static struct lvl4_pt initial_lvl4_pt_pool[INITIAL_LVL4_PT_COUNT]; > - > -/* Only reserve minimum Partition and Process tables */ > #define PATB_SIZE_LOG2 16 /* Only supported partition table size on POWER9 */ > #define PATB_SIZE (1UL << PATB_SIZE_LOG2) > -#define PRTB_SIZE_LOG2 12 > +#define PRTB_SIZE_LOG2 24 /* Maximum process table size on POWER9 */ > #define PRTB_SIZE (1UL << PRTB_SIZE_LOG2) > > -static struct patb_entry > - __aligned(PATB_SIZE) initial_patb[PATB_SIZE / sizeof(struct patb_entry)]; > +static struct patb_entry *initial_patb; > +static struct prtb_entry *initial_prtb; > > -static struct prtb_entry > - __aligned(PRTB_SIZE) initial_prtb[PRTB_SIZE / sizeof(struct prtb_entry)]; > +static mfn_t __initdata min_alloc_mfn = {-1}; > +static mfn_t __initdata max_alloc_mfn = {0}; > > -static __init struct lvl1_pd *lvl1_pd_pool_alloc(void) > +/* > + * A thin wrapper for alloc_boot_pages that keeps track of the maximum and > + * minimum mfns that have been allocated. This information is used by > + * setup_initial_mapping to include the allocated pages in the initial > + * page mapping. > + */ > +static mfn_t __init initial_page_alloc(unsigned long nr_pfns, > + unsigned long pfn_align) > { > - if ( initial_lvl1_pd_pool_used >= INITIAL_LVL1_PD_COUNT ) > - { > - early_printk("Ran out of space for LVL1 PD!\n"); > - die(); > - } > + mfn_t mfn_first, mfn_last; > > - return &initial_lvl1_pd_pool[initial_lvl1_pd_pool_used++]; > -} > + mfn_first = alloc_boot_pages(nr_pfns, pfn_align); > + mfn_last = _mfn(mfn_x(mfn_first) + nr_pfns - 1); Please can you use mfn_add() here? > -static __init struct lvl2_pd *lvl2_pd_pool_alloc(void) > -{ > - if ( initial_lvl2_lvl3_pd_pool_used >= INITIAL_LVL2_LVL3_PD_COUNT ) > - { > - early_printk("Ran out of space for LVL2/3 PD!\n"); > - die(); > - } > + min_alloc_mfn = _mfn(min(mfn_x(min_alloc_mfn), mfn_x(mfn_first))); > + max_alloc_mfn = _mfn(max(mfn_x(max_alloc_mfn), mfn_x(mfn_last))); Together with the comment ahead of the function - is there some kind of assumption here that this range won't span almost all of system memory? E.g. expecting allocations to be almost contiguous? If so, I wonder how reliable this is, and whether using a rangeset wouldn't be better here. > @@ -105,81 +138,47 @@ static void __init setup_initial_mapping(struct lvl1_pd > *lvl1, > die(); > } > > + /* Identity map Xen itself */ > for ( page_addr = map_start; page_addr < map_end; page_addr += PAGE_SIZE > ) > { > - struct lvl2_pd *lvl2; > - struct lvl3_pd *lvl3; > - struct lvl4_pt *lvl4; > - pde_t *pde; > - pte_t *pte; > - > - /* Allocate LVL 2 PD if necessary */ > - pde = pt_entry(lvl1, page_addr); > - if ( !pde_is_valid(*pde) ) > - { > - lvl2 = lvl2_pd_pool_alloc(); > - *pde = paddr_to_pde(__pa(lvl2), PDE_VALID, > - XEN_PT_ENTRIES_LOG2_LVL_2); > - } > - else > - lvl2 = __va(pde_to_paddr(*pde)); > + unsigned long flags; > > - /* Allocate LVL 3 PD if necessary */ > - pde = pt_entry(lvl2, page_addr); > - if ( !pde_is_valid(*pde) ) > + if ( is_kernel_text(page_addr) || is_kernel_inittext(page_addr) ) > { > - lvl3 = lvl3_pd_pool_alloc(); > - *pde = paddr_to_pde(__pa(lvl3), PDE_VALID, > - XEN_PT_ENTRIES_LOG2_LVL_3); > + radix_dprintk("%016lx being marked as TEXT (RX)\n", page_addr); > + flags = PTE_XEN_RX; > } > - else > - lvl3 = __va(pde_to_paddr(*pde)); > - > - /* Allocate LVL 4 PT if necessary */ > - pde = pt_entry(lvl3, page_addr); > - if ( !pde_is_valid(*pde) ) > + else if ( is_kernel_rodata(page_addr) ) > { > - lvl4 = lvl4_pt_pool_alloc(); > - *pde = paddr_to_pde(__pa(lvl4), PDE_VALID, > - XEN_PT_ENTRIES_LOG2_LVL_4); > + radix_dprintk("%016lx being marked as RODATA (RO)\n", page_addr); > + flags = PTE_XEN_RO; > } > else > - lvl4 = __va(pde_to_paddr(*pde)); > - > - /* Finally, create PTE in LVL 4 PT */ > - pte = pt_entry(lvl4, page_addr); > - if ( !pte_is_valid(*pte) ) > { > - unsigned long paddr = (page_addr - map_start) + phys_base; > - unsigned long flags; > - > - radix_dprintk("%016lx being mapped to %016lx\n", paddr, > page_addr); > - if ( is_kernel_text(page_addr) || is_kernel_inittext(page_addr) ) > - { > - radix_dprintk("%016lx being marked as TEXT (RX)\n", > page_addr); > - flags = PTE_XEN_RX; > - } > - else if ( is_kernel_rodata(page_addr) ) > - { > - radix_dprintk("%016lx being marked as RODATA (RO)\n", > page_addr); > - flags = PTE_XEN_RO; > - } > - else > - { > - radix_dprintk("%016lx being marked as DEFAULT (RW)\n", > page_addr); > - flags = PTE_XEN_RW; > - } > - > - *pte = paddr_to_pte(paddr, flags); > - radix_dprintk("%016lx is the result of PTE map\n", > - paddr_to_pte(paddr, flags).pte); > - } > - else > - { > - early_printk("BUG: Tried to create PTE for already-mapped > page!"); > - die(); > + radix_dprintk("%016lx being marked as DEFAULT (RW)\n", > page_addr); > + flags = PTE_XEN_RW; > } > + > + map_page_initial(lvl1, page_addr, (page_addr - map_start) + > phys_base, flags); > + } > + > + previous_max_alloc_mfn = max_alloc_mfn; > + > + /* > + * Identity map all pages we've allocated for paging structures. This act > + * itself will allocate more pages, so continue until we've mapped from > + * `max_alloc_mfn` down to `min_alloc_mfn`. This assumes that the heap > grows > + * downwards, which matches the behavior of alloc_boot_pages. > + */ > + for ( page_addr = (vaddr_t)__va(mfn_to_maddr(max_alloc_mfn)); > + mfn_to_maddr(min_alloc_mfn) <= __pa(page_addr); > + page_addr -= PAGE_SIZE) > + { > + map_page_initial(lvl1, page_addr, __pa(page_addr), PTE_XEN_RW); > } > + > + if ( mfn_x(previous_max_alloc_mfn) != mfn_x(max_alloc_mfn) ) > + panic("Early page heap unexpectedly grew upwards\n"); > } Oh, yet another assumption on allocator behavior. Jan
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