On 20.07.22 14:08, Jason A. Donenfeld wrote: > In order for hosts running inside of TCG to initialize the kernel's > random number generator, we should support the PRNO_TRNG instruction, > backed in the usual way with the qemu_guest_getrandom helper. This is > confirmed working on Linux 5.19-rc6. > > Cc: Thomas Huth <th...@redhat.com> > Cc: David Hildenbrand <da...@redhat.com> > Cc: Richard Henderson <richard.hender...@linaro.org> > Cc: Cornelia Huck <coh...@redhat.com> > Cc: Harald Freudenberger <fre...@linux.ibm.com> > Cc: Holger Dengler <deng...@linux.ibm.com> > Signed-off-by: Jason A. Donenfeld <ja...@zx2c4.com> > --- > target/s390x/cpu_models.c | 2 -- > target/s390x/gen-features.c | 2 ++ > target/s390x/tcg/crypto_helper.c | 32 ++++++++++++++++++++++++++++++++ > 3 files changed, 34 insertions(+), 2 deletions(-) > > diff --git a/target/s390x/cpu_models.c b/target/s390x/cpu_models.c > index 1a562d2801..90aac3d795 100644 > --- a/target/s390x/cpu_models.c > +++ b/target/s390x/cpu_models.c > @@ -421,8 +421,6 @@ static void check_consistency(const S390CPUModel *model) > { S390_FEAT_DFP_FAST, S390_FEAT_DFP }, > { S390_FEAT_TRANSACTIONAL_EXE, S390_FEAT_STFLE_49 }, > { S390_FEAT_EDAT_2, S390_FEAT_EDAT}, > - { S390_FEAT_MSA_EXT_5, S390_FEAT_KIMD_SHA_512 }, > - { S390_FEAT_MSA_EXT_5, S390_FEAT_KLMD_SHA_512 }, > { S390_FEAT_MSA_EXT_4, S390_FEAT_MSA_EXT_3 }, > { S390_FEAT_SIE_CMMA, S390_FEAT_CMM }, > { S390_FEAT_SIE_CMMA, S390_FEAT_SIE_GSLS }, > diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c > index ad140184b9..3d333e2789 100644 > --- a/target/s390x/gen-features.c > +++ b/target/s390x/gen-features.c > @@ -749,6 +749,8 @@ static uint16_t qemu_V7_0[] = { > */ > static uint16_t qemu_MAX[] = { > S390_FEAT_VECTOR_ENH2, > + S390_FEAT_MSA_EXT_5, > + S390_FEAT_PRNO_TRNG, > }; > > /****** END FEATURE DEFS ******/ > diff --git a/target/s390x/tcg/crypto_helper.c > b/target/s390x/tcg/crypto_helper.c > index 138d9e7ad9..afd29f9cf0 100644 > --- a/target/s390x/tcg/crypto_helper.c > +++ b/target/s390x/tcg/crypto_helper.c > @@ -12,12 +12,38 @@ > > #include "qemu/osdep.h" > #include "qemu/main-loop.h" > +#include "qemu/guest-random.h" > #include "s390x-internal.h" > #include "tcg_s390x.h" > #include "exec/helper-proto.h" > #include "exec/exec-all.h" > #include "exec/cpu_ldst.h" > > +static void fill_buf_random(CPUS390XState *env, uintptr_t ra, > + uint64_t *buf_reg, uint64_t *len_reg) > +{ > + uint8_t tmp[256]; > + uint64_t len = *len_reg; > + int reg_len = 64; > + > + if (!(env->psw.mask & PSW_MASK_64)) { > + len = (uint32_t)len; > + reg_len = (env->psw.mask & PSW_MASK_32) ? 32 : 24; > + } > + > + while (len) { > + size_t block = MIN(len, sizeof(tmp)); > + > + qemu_guest_getrandom_nofail(tmp, block); > + for (size_t i = 0; i < block; ++i) { > + cpu_stb_data_ra(env, wrap_address(env, *buf_reg), > tmp[i], ra); > + *buf_reg = deposit64(*buf_reg, 0, reg_len, *buf_reg > + 1); > + --*len_reg; > + } > + len -= block; > + }
Yeah, that's better, although kind-off hard to read. We could process one guest page at a time, similar to how we handle target/s390x/tcg/mem_helper.c:access_memset and friends nowadays. But I won't force you to do that ;) This here is good enough for now, with room for improvement regarding efficiency. I did not review the doc in detail once again, maybe I get to that later this week. -- Thanks, David / dhildenb