From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34835) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQRzX-000893-P1 for qemu-devel@nongnu.org; Wed, 06 Jun 2018 02:32:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fQRzU-0007ml-IX for qemu-devel@nongnu.org; Wed, 06 Jun 2018 02:32:19 -0400 Date: Wed, 6 Jun 2018 16:32:06 +1000 From: David Gibson Message-ID: <20180606063206.GI17757@umbus.fritz.box> References: <20180606060830.25942-1-clg@kaod.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Li7ckgedzMh1NgdW" Content-Disposition: inline In-Reply-To: <20180606060830.25942-1-clg@kaod.org> Subject: Re: [Qemu-devel] [PATCH] target/ppc: extend eieio for POWER9 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: =?iso-8859-1?Q?C=E9dric?= Le Goater Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org --Li7ckgedzMh1NgdW Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Jun 06, 2018 at 08:08:30AM +0200, C=E9dric Le Goater wrote: > POWER9 introduced a new variant of the eieio instruction using bit 6 > as a hint to tell the CPU it is a store-forwarding barrier. >=20 > The usage of this eieio extension was recently added in Linux 4.17 > which activated the "support for a store forwarding barrier at kernel > entry/exit". >=20 > Unfortunately, it is not possible to insert this new eieio instruction > without considerable change in ppc_tr_translate_insn(). So instead we > loosen the QEMU eieio instruction mask. The gen_eieio() helper is > modified to test for bit6 and a custom instruction flag to catch > invalid eieio opcodes on non-POWER9 CPUs. >=20 > Signed-off-by: C=E9dric Le Goater > --- > target/ppc/cpu.h | 5 ++++- > target/ppc/translate.c | 19 +++++++++++++++++-- > target/ppc/translate_init.inc.c | 3 ++- > 3 files changed, 23 insertions(+), 4 deletions(-) >=20 > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h > index 0247c1f04c37..021c9b2f10d1 100644 > --- a/target/ppc/cpu.h > +++ b/target/ppc/cpu.h > @@ -2206,6 +2206,9 @@ enum { > /* POWER ISA 3.0 = */ > PPC2_ISA300 =3D 0x0000000000080000ULL, > =20 > + /* POWER ISA 3.0 eieio variants = */ > + PPC2_MEM_EIEIO2 =3D 0x0000000000100000ULL, > + > #define PPC_TCG_INSNS2 (PPC2_BOOKE206 | PPC2_VSX | PPC2_PRCNTL | PPC2_DB= RX | \ > PPC2_ISA205 | PPC2_VSX207 | PPC2_PERM_ISA206 | \ > PPC2_DIVE_ISA206 | PPC2_ATOMIC_ISA206 | \ > @@ -2213,7 +2216,7 @@ enum { > PPC2_BCTAR_ISA207 | PPC2_LSQ_ISA207 | \ > PPC2_ALTIVEC_207 | PPC2_ISA207S | PPC2_DFP | \ > PPC2_FP_CVT_S64 | PPC2_TM | PPC2_PM_ISA206 | \ > - PPC2_ISA300) > + PPC2_ISA300 | PPC2_MEM_EIEIO2) > }; > =20 > /***********************************************************************= ******/ > diff --git a/target/ppc/translate.c b/target/ppc/translate.c > index 8ba8f67dc513..a73ef02aef1d 100644 > --- a/target/ppc/translate.c > +++ b/target/ppc/translate.c > @@ -2967,7 +2967,22 @@ static void gen_stswx(DisasContext *ctx) > /* eieio */ > static void gen_eieio(DisasContext *ctx) > { > - tcg_gen_mb(TCG_MO_LD_ST | TCG_BAR_SC); > + TCGBar bar =3D TCG_MO_LD_ST; > + > + /* > + * POWER9 has a eieio instruction variant using bit 6 as a hint to > + * tell the CPU it is a store-forwarding barrier. > + */ > + if (ctx->opcode & 0x2000000) { > + if (!(ctx->insns_flags2 & PPC2_MEM_EIEIO2)) { Since we have to adapt the gen_eieio code anyway we don't really need the new instruction flag - we can just reuse PPC2_ISA300 for it. > + qemu_log_mask(LOG_GUEST_ERROR, "invalid eieio using bit 6 at= @" > + TARGET_FMT_lx "\n", ctx->base.pc_next - 4); Logging is ok, but it's not enough in this context - that will turn the variant eieio into a no-op. You need to actually generate an invalid instruction exception here, which is what I assume will happen if you try to execute the new variant on a POWER8: gen_inval_exception(ctx, POWERPC_EXCP_INVAL_INVAL); > + return; > + } > + bar =3D TCG_MO_ST_LD; > + } > + > + tcg_gen_mb(bar | TCG_BAR_SC); > } > =20 > #if !defined(CONFIG_USER_ONLY) > @@ -6483,7 +6498,7 @@ GEN_HANDLER(lswi, 0x1F, 0x15, 0x12, 0x00000001, PPC= _STRING), > GEN_HANDLER(lswx, 0x1F, 0x15, 0x10, 0x00000001, PPC_STRING), > GEN_HANDLER(stswi, 0x1F, 0x15, 0x16, 0x00000001, PPC_STRING), > GEN_HANDLER(stswx, 0x1F, 0x15, 0x14, 0x00000001, PPC_STRING), > -GEN_HANDLER(eieio, 0x1F, 0x16, 0x1A, 0x03FFF801, PPC_MEM_EIEIO), > +GEN_HANDLER(eieio, 0x1F, 0x16, 0x1A, 0x01FFF801, PPC_MEM_EIEIO), > GEN_HANDLER(isync, 0x13, 0x16, 0x04, 0x03FFF801, PPC_MEM), > GEN_HANDLER_E(lbarx, 0x1F, 0x14, 0x01, 0, PPC_NONE, PPC2_ATOMIC_ISA206), > GEN_HANDLER_E(lharx, 0x1F, 0x14, 0x03, 0, PPC_NONE, PPC2_ATOMIC_ISA206), > diff --git a/target/ppc/translate_init.inc.c b/target/ppc/translate_init.= inc.c > index 1a89017ddea8..6b70f6dc5a2c 100644 > --- a/target/ppc/translate_init.inc.c > +++ b/target/ppc/translate_init.inc.c > @@ -8847,7 +8847,8 @@ POWERPC_FAMILY(POWER9)(ObjectClass *oc, void *data) > PPC2_FP_TST_ISA206 | PPC2_BCTAR_ISA207 | > PPC2_LSQ_ISA207 | PPC2_ALTIVEC_207 | > PPC2_ISA205 | PPC2_ISA207S | PPC2_FP_CVT_S64 | > - PPC2_TM | PPC2_PM_ISA206 | PPC2_ISA300 | PPC2_PR= CNTL; > + PPC2_TM | PPC2_PM_ISA206 | PPC2_ISA300 | PPC2_PR= CNTL | > + PPC2_MEM_EIEIO2; > pcc->msr_mask =3D (1ull << MSR_SF) | > (1ull << MSR_TM) | > (1ull << MSR_VR) | --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --Li7ckgedzMh1NgdW Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEdfRlhq5hpmzETofcbDjKyiDZs5IFAlsXf+QACgkQbDjKyiDZ s5KhLw/9E59nw4BYT/2RXaZgdl3nIeM4ud+3/36RGGNEAnvxxI5r65NxPgk63xGX M5d9M4KKvAT9/rHzXgwRfx41iEA7ItWXqfvV4baLEiAFb2ONwydWmjt/Ba/8wCtq ETa20mjGevLjS1htWuzZGTBgx2l8Ct+uadJ3gLLARePOGMbg9JtfcGKGOJ0ouxSZ OcabUlv7u2vmeRTm9+gWTWq4WskfkVxAQAs9HKlXKjehNjOPaMrYBe8um5/6l1ib vqz290a25xo9QJmbyzhi9se6Mimkq9VVL35J1GImDuNI84R4uayr1hjQDHYtGXLG +5DbkcPVzqpMPdHojqRs2Z7xpaJZHYM7R6JdpnZZwn5QRT57paiIVS5w+/BfPCln R/M8gJ5ou7qdF2JrUooOE0STAPGyv5uFL6Om8nZx1j6kBqPHvjmRO0m/qvLo3e4L /PkD3kjtyhsBoeFhCIx1jvxY6Kf+fVL1smO3SNuV/VpS8mWlpJbvOyZJN6E929Dp WbmvW3iuZer+Km7S4pK/9G/o5cTTpXHmYz5WEW9aRE7lCAPZAodmIEmjjiYOhd5a g0YMycBMIRtNs93eg1ZusY528JJUusX9R2+JP8C7HtokQxKcheBArlXei6x6/gi1 ads8VLRNEKdYjey78jQQ1kBnY7q77fj6opr14A/J0VA2YBAvTA0= =E2Fw -----END PGP SIGNATURE----- --Li7ckgedzMh1NgdW--