[PATCH v8 2/2] 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.
Cc: Thomas Huth
Cc: David Hildenbrand
Cc: Christian Borntraeger
Cc: Richard Henderson
Cc: Cornelia Huck
Cc: Harald Freudenberger
Cc: Holger Dengler
Signed-off-by: Jason A. Donenfeld
---
target/s390x/gen-features.c | 1 +
target/s390x/tcg/crypto_helper.c | 30 ++
2 files changed, 31 insertions(+)
diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 14a7f2ae90..aaade67574 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -754,6 +754,7 @@ 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 **/
diff --git a/target/s390x/tcg/crypto_helper.c b/target/s390x/tcg/crypto_helper.c
index 02073ec70b..0daa9a2dd9 100644
--- a/target/s390x/tcg/crypto_helper.c
+++ b/target/s390x/tcg/crypto_helper.c
@@ -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"
@@ -173,6 +174,31 @@ static int klmd_sha512(CPUS390XState *env, uintptr_t ra,
uint64_t parameter_bloc
return 0;
}
+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)
{
@@ -215,6 +241,10 @@ uint32_t HELPER(msa)(CPUS390XState *env, uint32_t r1,
uint32_t r2, uint32_t r3,
return klmd_sha512(env, ra, env->regs[1], &env->regs[r2],
&env->regs[r2 + 1]);
}
break;
+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();
--
2.37.3
Re: [PATCH v8 2/2] target/s390x: support PRNO_TRNG instruction
On 21.09.22 12:07, 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. Cc: Thomas Huth Cc: David Hildenbrand Cc: Christian Borntraeger Cc: Richard Henderson Cc: Cornelia Huck Cc: Harald Freudenberger Cc: Holger Dengler Signed-off-by: Jason A. Donenfeld Thanks! Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb
Re: [PATCH v8 2/2] target/s390x: support PRNO_TRNG instruction
On 21/09/2022 12.07, 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.
Cc: Thomas Huth
Cc: David Hildenbrand
Cc: Christian Borntraeger
Cc: Richard Henderson
Cc: Cornelia Huck
Cc: Harald Freudenberger
Cc: Holger Dengler
Signed-off-by: Jason A. Donenfeld
---
target/s390x/gen-features.c | 1 +
target/s390x/tcg/crypto_helper.c | 30 ++
2 files changed, 31 insertions(+)
diff --git a/target/s390x/gen-features.c b/target/s390x/gen-features.c
index 14a7f2ae90..aaade67574 100644
--- a/target/s390x/gen-features.c
+++ b/target/s390x/gen-features.c
@@ -754,6 +754,7 @@ 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 **/
diff --git a/target/s390x/tcg/crypto_helper.c b/target/s390x/tcg/crypto_helper.c
index 02073ec70b..0daa9a2dd9 100644
--- a/target/s390x/tcg/crypto_helper.c
+++ b/target/s390x/tcg/crypto_helper.c
@@ -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"
@@ -173,6 +174,31 @@ static int klmd_sha512(CPUS390XState *env, uintptr_t ra,
uint64_t parameter_bloc
return 0;
}
+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)
{
@@ -215,6 +241,10 @@ uint32_t HELPER(msa)(CPUS390XState *env, uint32_t r1,
uint32_t r2, uint32_t r3,
return klmd_sha512(env, ra, env->regs[1], &env->regs[r2],
&env->regs[r2 + 1]);
}
break;
+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;
Thanks, patch looks fine to me!
(if we ever have another instruction that uses fc 114, we might want to
check "type" here, too, but that can also be added later, of course)
Thomas
Re: [PATCH v8 2/2] target/s390x: support PRNO_TRNG instruction
On Mon, Sep 26, 2022 at 5:11 PM Thomas Huth wrote: > Seems like this is even working fine with older Linux kernels ... Oh good! your patch accidentally broke test_s390x_devices in tests/avocado/machine_s390_ccw_virtio.py: This test adds two virtio-rng devices to the guest, then ejects them to see whether /dev/hwrng will be gone ... which does not happen anymore with the prno-trng feature enabled :-) > > I'm going to squash this one-liner to fix this issue: Seems reasonable. Thanks. Jason
Re: [PATCH v8 2/2] target/s390x: support PRNO_TRNG instruction
On 21/09/2022 12.07, 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. Cc: Thomas Huth Cc: David Hildenbrand Cc: Christian Borntraeger Cc: Richard Henderson Cc: Cornelia Huck Cc: Harald Freudenberger Cc: Holger Dengler Signed-off-by: Jason A. Donenfeld --- target/s390x/gen-features.c | 1 + target/s390x/tcg/crypto_helper.c | 30 ++ 2 files changed, 31 insertions(+) Seems like this is even working fine with older Linux kernels ... your patch accidentally broke test_s390x_devices in tests/avocado/machine_s390_ccw_virtio.py: This test adds two virtio-rng devices to the guest, then ejects them to see whether /dev/hwrng will be gone ... which does not happen anymore with the prno-trng feature enabled :-) I'm going to squash this one-liner to fix this issue: diff a/tests/avocado/machine_s390_ccw_virtio.py b/tests/avocado/machine_s390_ccw_virtio.py --- a/tests/avocado/machine_s390_ccw_virtio.py +++ b/tests/avocado/machine_s390_ccw_virtio.py @@ -66,6 +66,7 @@ def test_s390x_devices(self): '-kernel', kernel_path, '-initrd', initrd_path, '-append', kernel_command_line, + '-cpu', 'max,prno-trng=off', '-device', 'virtio-net-ccw,devno=fe.1.', '-device', 'virtio-rng-ccw,devno=fe.2.,max_revision=0,id=rn1', Thomas
