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target/s390x: support PRNO_TRNG instruction 

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.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Message-Id: <20220921100729.2942008-2-Jason@zx2c4.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
[thuth: turn prno-trng off in avocado test to avoid breaking it]
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Jason A. Donenfeld 2022-09-21 12:07:29 +02:00 committed by Thomas Huth
parent 9f17bfdab4
commit 3dbc5fdacb
3 changed files with 32 additions and 0 deletions
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1
target/s390x/gen-features.c
View File

@ -757,6 +757,7 @@ static uint16_t qemu_MAX[] = {
S390_FEAT_MSA_EXT_5,
S390_FEAT_KIMD_SHA_512,
S390_FEAT_KLMD_SHA_512,
S390_FEAT_PRNO_TRNG,
};
/****** END FEATURE DEFS ******/

30
target/s390x/tcg/crypto_helper.c
View File

@ -14,6 +14,7 @@
#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"
@ -244,6 +245,31 @@ static int cpacf_sha512(CPUS390XState *env, uintptr_t ra, uint64_t param_addr,
return !len ? 0 : 3;
}
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 buf_reg_len = 64;
if (!(env->psw.mask & PSW_MASK_64)) {
len = (uint32_t)len;
buf_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, buf_reg_len, *buf_reg + 1);
--*len_reg;
}
len -= block;
}
}
uint32_t HELPER(msa)(CPUS390XState *env, uint32_t r1, uint32_t r2, uint32_t r3,
uint32_t type)
{
@ -281,6 +307,10 @@ uint32_t HELPER(msa)(CPUS390XState *env, uint32_t r1, uint32_t r2, uint32_t r3,
case 3: /* CPACF_*_SHA_512 */
return cpacf_sha512(env, ra, env->regs[1], &env->regs[r2],
&env->regs[r2 + 1], type);
case 114: /* CPACF_PRNO_TRNG */
fill_buf_random(env, ra, &env->regs[r1], &env->regs[r1 + 1]);
fill_buf_random(env, ra, &env->regs[r2], &env->regs[r2 + 1]);
break;
default:
/* we don't implement any other subfunction yet */
g_assert_not_reached();

1
tests/avocado/machine_s390_ccw_virtio.py
View File

@ -66,6 +66,7 @@ class S390CCWVirtioMachine(QemuSystemTest):
'-kernel', kernel_path,
'-initrd', initrd_path,
'-append', kernel_command_line,
'-cpu', 'max,prno-trng=off',
'-device', 'virtio-net-ccw,devno=fe.1.1111',
'-device',
'virtio-rng-ccw,devno=fe.2.0000,max_revision=0,id=rn1',