On 19/10/17 17:47, Will Deacon wrote: > On Mon, Oct 09, 2017 at 04:20:24PM +0100, Marc Zyngier wrote: >> We currently tightly couple dcache clean with icache invalidation, >> but KVM could do without the initial flush to PoU, as we've >> already flushed things to PoC. >> >> Let's introduce invalidate_icache_range which is limited to >> invalidating the icache from the linear mapping (and thus >> has none of the userspace fault handling complexity), and >> wire it in KVM instead of flush_icache_range. >> >> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> >> --- >> arch/arm64/include/asm/cacheflush.h | 8 ++++++++ >> arch/arm64/include/asm/kvm_mmu.h | 4 ++-- >> arch/arm64/mm/cache.S | 24 ++++++++++++++++++++++++ >> 3 files changed, 34 insertions(+), 2 deletions(-) > > [...] > >> diff --git a/arch/arm64/mm/cache.S b/arch/arm64/mm/cache.S >> index 7f1dbe962cf5..0c330666a8c9 100644 >> --- a/arch/arm64/mm/cache.S >> +++ b/arch/arm64/mm/cache.S >> @@ -80,6 +80,30 @@ USER(9f, ic ivau, x4 ) // invalidate I line PoU >> ENDPROC(flush_icache_range) >> ENDPROC(__flush_cache_user_range) >> >> +/* >> + * invalidate_icache_range(start,end) >> + * >> + * Ensure that the I cache is invalid within specified region. This >> + * assumes that this is done on the linear mapping. Do not use it >> + * on a userspace range, as this may fault horribly. >> + * >> + * - start - virtual start address of region >> + * - end - virtual end address of region >> + */ >> +ENTRY(invalidate_icache_range) >> + icache_line_size x2, x3 >> + sub x3, x2, #1 >> + bic x4, x0, x3 >> +1: >> + ic ivau, x4 // invalidate I line PoU >> + add x4, x4, x2 >> + cmp x4, x1 >> + b.lo 1b >> + dsb ish >> + isb >> + ret >> +ENDPROC(invalidate_icache_range) > > Is there a good reason not to make this work for user addresses? If it's as > simple as adding a USER annotation and a fallback, then we should wrap that > in a macro and reuse it for __flush_cache_user_range. Fair enough. I've done that now (with an optional label that triggers the generation of a USER() annotation). I'll post the revised series shortly. Thanks, M. -- Jazz is not dead. It just smells funny...
