Michael Ellerman <m...@ellerman.id.au> writes: > Daniel Axtens <d...@axtens.net> writes: >> Hi Christophe, >> >> This breaks booting a radix KVM guest with 4k pages for me: >> >> make pseries_le_defconfig >> scripts/config -d CONFIG_PPC_64K_PAGES >> scripts/config -e CONFIG_PPC_4K_PAGES >> make vmlinux >> sudo qemu-system-ppc64 -enable-kvm -M pseries -m 1G -nographic -vga none >> -smp 4 -cpu host -kernel vmlinux >> >> Boot hangs after printing 'Booting Linux via __start()' and qemu's 'info >> registers' reports that it's stuck at the instruction fetch exception. >> >> My host is Power9, 64k page size radix, and >> gcc (Ubuntu 9.3.0-17ubuntu1~20.04) 9.3.0, GNU ld (GNU Binutils for Ubuntu) >> 2.34 >> > > ... >>> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S >>> index 730838c7ca39..79f2d1e61abd 100644 >>> --- a/arch/powerpc/kernel/head_64.S >>> +++ b/arch/powerpc/kernel/head_64.S >>> @@ -997,18 +997,3 @@ start_here_common: >>> 0: trap >>> EMIT_BUG_ENTRY 0b, __FILE__, __LINE__, 0 >>> .previous >>> - >>> -/* >>> - * We put a few things here that have to be page-aligned. >>> - * This stuff goes at the beginning of the bss, which is page-aligned. >>> - */ >>> - .section ".bss" >>> -/* >>> - * pgd dir should be aligned to PGD_TABLE_SIZE which is 64K. >>> - * We will need to find a better way to fix this >>> - */ >>> - .align 16 >>> - >>> - .globl swapper_pg_dir >>> -swapper_pg_dir: >>> - .space PGD_TABLE_SIZE > > This is now 4K aligned whereas it used to be 64K. > > This fixes it and is not completely ugly? > > diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c > index 1707ab580ee2..298469beaa90 100644 > --- a/arch/powerpc/mm/pgtable.c > +++ b/arch/powerpc/mm/pgtable.c > @@ -28,7 +28,13 @@ > #include <asm/hugetlb.h> > #include <asm/pte-walk.h> > > -pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __page_aligned_bss; > +#ifdef CONFIG_PPC64 > +#define PGD_ALIGN 0x10000 > +#else > +#define PGD_ALIGN PAGE_SIZE > +#endif > + > +pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __section(".bss..page_aligned") > __aligned(PGD_ALIGN);
The fix works for me, thank you. Kind regards, Daniel > > static inline int is_exec_fault(void) > { > > > cheers