Joel Stanley <j...@jms.id.au> writes: > On Mon, Jan 8, 2018 at 8:54 AM, Michael Ellerman <m...@ellerman.id.au> wrote: >> On some CPUs we can prevent the Meltdown vulnerability by flushing the >> L1-D cache on exit from kernel to user mode, and from hypervisor to >> guest. > > Super minor nitpicks below. Don't let this hold up your work. > >> --- a/arch/powerpc/kernel/exceptions-64s.S >> +++ b/arch/powerpc/kernel/exceptions-64s.S >> @@ -1449,6 +1449,88 @@ masked_##_H##interrupt: >> \ >> b .; \ >> MASKED_DEC_HANDLER(_H) >> >> +TRAMP_REAL_BEGIN(rfi_flush_fallback) >> + SET_SCRATCH0(r13); >> + GET_PACA(r13); >> + std r9,PACA_EXRFI+EX_R9(r13) >> + std r10,PACA_EXRFI+EX_R10(r13) >> + std r11,PACA_EXRFI+EX_R11(r13) >> + std r12,PACA_EXRFI+EX_R12(r13) >> + std r8,PACA_EXRFI+EX_R13(r13) >> + mfctr r9 >> + ld r10,PACA_RFI_FLUSH_FALLBACK_AREA(r13) >> + ld r11,PACA_L1D_FLUSH_SETS(r13) >> + ld r12,PACA_L1D_FLUSH_CONGRUENCE(r13) >> + /* >> + * The load adresses are at staggered offsets within cachelines, >> + * which suits some pipelines better (on others it should not >> + * hurt. > > Nit: missing ) on the last line.
Thanks. >> --- a/arch/powerpc/lib/feature-fixups.c >> +++ b/arch/powerpc/lib/feature-fixups.c >> @@ -116,6 +116,47 @@ void do_feature_fixups(unsigned long value, void >> *fixup_start, void *fixup_end) >> } >> } >> >> +#ifdef CONFIG_PPC_BOOK3S_64 >> +void do_rfi_flush_fixups(enum l1d_flush_type types) >> +{ >> + unsigned int instrs[3], *dest; >> + long *start, *end; >> + int i; >> + >> + start = PTRRELOC(&__start___rfi_flush_fixup), >> + end = PTRRELOC(&__stop___rfi_flush_fixup); >> + >> + instrs[0] = 0x60000000; /* nop */ >> + instrs[1] = 0x60000000; /* nop */ >> + instrs[2] = 0x60000000; /* nop */ >> + >> + if (types & L1D_FLUSH_FALLBACK) > > This looked a bit confusing on first read. Do we ever get > L1D_FLUSH_FALLBACK and the other types? If not, could it be made > clearer? > > if ( types & L1D_FLUSH_FALLBACK) > /* stuff */ > else > /* other types */ Yeah that would make more sense. I'm going to merge it as-is because that's whats been tested, and given the time of day I'm likely to break it if I try and refactor it. So we can clean it up once it's merged. cheers