On Wed, Sep 26, 2018 at 02:56:22PM +0100, Julien Thierry wrote: > When an EL2 entry of __kvm_hyp_vector is taken, it means an entry from a > lower EL was previously taken to exit the guest. Taking that lower EL entry > already applied BP hardening if it was needed, so there is no need to do > it again. > > Only apply BP hardening for exception coming from lower EL. > > Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx> > Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx > --- > arch/arm64/kernel/cpu_errata.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kernel/cpu_errata.c b/arch/arm64/kernel/cpu_errata.c > index dec1089..9db5ecc 100644 > --- a/arch/arm64/kernel/cpu_errata.c > +++ b/arch/arm64/kernel/cpu_errata.c > @@ -103,10 +103,16 @@ static void __copy_hyp_vect_bpi(int slot, const char *hyp_vecs_start, > void *dst = lm_alias(__bp_harden_hyp_vecs_start + slot * SZ_2K); > int i; > > - for (i = 0; i < SZ_2K; i += 0x80) > + /* > + * Only overwrite hyp entries for exceptions from lower EL. > + * Exception vection vector is 2K bytes, first 1K bytes concern > + * exception from EL2 (EL2t, EL2h), last 1K concert lower exception > + * levels (ELx-64bits, ELx-32bits). > + */ > + for (i = SZ_1K; i < SZ_2K; i += 0x80) > memcpy(dst + i, hyp_vecs_start, hyp_vecs_end - hyp_vecs_start); > > - __flush_icache_range((uintptr_t)dst, (uintptr_t)dst + SZ_2K); > + __flush_icache_range((uintptr_t)dst + SZ_1K, (uintptr_t)dst + SZ_2K); > } I'd personally find this clearer if you did: dst += SZ_1K; before the for loop and with your comment above it. Then the for loop becomes: for (i = 0; i < SZ_1K; i += 0x80) and the range of the cache maintenance is [dst, dst + SZ_1K) But I'll leave it up to Marc. Will _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
