From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4BA6B606A31E for ; Thu, 29 Oct 2026 23:22:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=SXAX849X; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=OeDHMRkV DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=N3gRoLc7yvRB1yDkBERo6UVcw5vuu8Tzkngj57Vi0dE=; b=SXAX849Xjp5DpkGqz/7bmCg8LS cZkqISlT9bA3aDn6VqTi6FqF/BVKd6cNptYpPVjKIRcuPy8Z6/oR3xQkkj7zzpLRVyZVULGAMXVLv eAgbVdIctDcd73CgpLsRx7St3RHx2sKNDQ6FncaApCFr+TqCI0q02EOhmGbAuvYK9ZDF0oUDasS6v 1gQj1M84YVAFjVE6oBKhyxuHJbNamH+OcfYqwHi8IedeetDcZg5/DK6Vb/VZluRXHhrw4AV5XAWbR P3d4MCeUWyhRHOVeu5emHyoHy3/s+K45lKsBy6na/6bSn77VlRsX4Lu6pz2uCVv/FBbiLjJwIMbb3 sZJbvUjQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMZRW-0000000AXHB-44Ak; Thu, 29 Oct 2026 23:21:58 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMZRU-0000000AXH5-3fOG for linux-arm-kernel@lists.infradead.org; Thu, 29 Oct 2026 23:21:56 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 1684D41AC8; Thu, 29 Oct 2026 23:21:56 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D3E901F01816; Thu, 29 Oct 2026 23:21:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793316116; bh=N3gRoLc7yvRB1yDkBERo6UVcw5vuu8Tzkngj57Vi0dE=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=OeDHMRkVizcxRN9N3vVP2Rr6664f8SXA17luor+yEvb3CmNZbugi9FU7GDecXQiRf 9qaUXqbPJ3rA7Dmadxspz7WfJCXoz4/60BO7EXgYSDQxIBhHhXYQ5VUi95AOqYEMgc yqdS2lhGSX1wbAXHl+O0WkoUVXbCQv4bMGvm+kxdVqANphliT50iJweStI0d/CRJrZ QN25FBK5i87iVpvu6c4F5z09Ci3tnzlpttoRzjueyUii4cjW6YL9AM8ohmw3rtq7Vw AlUGm2eibkPKCAJIpLafywkPbuqkAYFDXz6C/q5YyQv6hxTFx9knt12QlVYMU6YrS+ PHxJebv/xBnuQ== Date: Thu, 29 Oct 2026 23:21:50 +0000 From: Conor Dooley To: Srirangan Madhavan Cc: mark.rutland@arm.com, lpieralisi@kernel.org, sudeep.holla@kernel.org, jic23@kernel.org, catalin.marinas@arm.com, will@kernel.org, andre.przywara@arm.com, aneesh.kumar@kernel.org, Souvik.Chakravarty@arm.com, treding@nvidia.com, jonathanh@nvidia.com, bence.csokas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-tegra@vger.kernel.org, Jonathan Cameron Subject: Re: [PATCH v5 2/2] cache: add SMCCC-backed cache invalidate provider Message-ID: <20261029-feline-monastery-07bf67308136@spud> References: <20261021224557.1827361-1-smadhavan@nvidia.com> <20261021224557.1827361-3-smadhavan@nvidia.com> X-Archived-By: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="fabG0ZF/qX/zSjOV" Content-Disposition: inline In-Reply-To: <20261021224557.1827361-3-smadhavan@nvidia.com> X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 --fabG0ZF/qX/zSjOV Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Oct 21, 2026 at 10:45:57PM +0000, Srirangan Madhavan wrote: > Add a cache maintenance provider for the cache clean+invalidate interface > defined by Arm DEN0028 v1.7. >=20 > Register the interface attributes function as an SMCCC device and bind the > provider through the SMCCC bus. The provider reads the firmware attributes > during probe and serializes cache maintenance calls. It handles transient > BUSY and RATE_LIMITED responses with bounded retries. It also registers > with the generic cache coherency framework used by memregion callers. >=20 > Signed-off-by: Srirangan Madhavan > Reviewed-by: Jonathan Cameron I acked this on v3, but I don't see it here or a reason for why it isn't. Ultimately, you're only harming yourself but still. Unless the arm64 guys pipe up and expect me to take this, Acked-by: Conor Dooley because it's so tied to arm architectural stuff. Cheers, Conor. > --- > drivers/cache/Kconfig | 11 +++ > drivers/cache/Makefile | 2 + > drivers/cache/arm_smccc_cache.c | 156 ++++++++++++++++++++++++++++++++ > drivers/firmware/smccc/smccc.c | 5 + > 4 files changed, 174 insertions(+) > create mode 100644 drivers/cache/arm_smccc_cache.c >=20 > diff --git a/drivers/cache/Kconfig b/drivers/cache/Kconfig > index 1518449d47b5..57fd1823dec5 100644 > --- a/drivers/cache/Kconfig > +++ b/drivers/cache/Kconfig > @@ -42,6 +42,17 @@ menuconfig CACHEMAINT_FOR_HOTPLUG > =20 > if CACHEMAINT_FOR_HOTPLUG > =20 > +config ARM_SMCCC_CACHE > + bool "Arm SMCCC cache maintenance provider" > + depends on ARM64 && HAVE_ARM_SMCCC_DISCOVERY > + help > + Enable support for the Arm SMCCC cache clean+invalidate > + interface as a provider for memory hotplug-like cache > + maintenance operations. > + The provider registers only when firmware advertises the > + SMCCC calls and attributes, so systems without firmware support > + continue without this registered provider. > + > config HISI_SOC_HHA > tristate "HiSilicon Hydra Home Agent (HHA) device driver" > depends on (ARM64 && ACPI) || COMPILE_TEST > diff --git a/drivers/cache/Makefile b/drivers/cache/Makefile > index b3362b15d6c1..55736a032d6f 100644 > --- a/drivers/cache/Makefile > +++ b/drivers/cache/Makefile > @@ -4,4 +4,6 @@ obj-$(CONFIG_AX45MP_L2_CACHE) +=3D ax45mp_cache.o > obj-$(CONFIG_SIFIVE_CCACHE) +=3D sifive_ccache.o > obj-$(CONFIG_STARFIVE_STARLINK_CACHE) +=3D starfive_starlink_cache.o > =20 > +# Providers below depend on CACHEMAINT_FOR_HOTPLUG. > +obj-$(CONFIG_ARM_SMCCC_CACHE) +=3D arm_smccc_cache.o > obj-$(CONFIG_HISI_SOC_HHA) +=3D hisi_soc_hha.o > diff --git a/drivers/cache/arm_smccc_cache.c b/drivers/cache/arm_smccc_ca= che.c > new file mode 100644 > index 000000000000..abe6881f3de3 > --- /dev/null > +++ b/drivers/cache/arm_smccc_cache.c > @@ -0,0 +1,156 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2026 NVIDIA Corporation > + * > + * Arm SMCCC cache maintenance provider using the cache clean+invalidate > + * interface defined by Arm DEN0028 v1.7. > + */ > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#define SMCCC_CACHE_MAX_RETRIES 5 > +#define SMCCC_CACHE_DEFAULT_DELAY_US 1000UL > +#define SMCCC_CACHE_MAX_DELAY_US 20000UL > + > +struct smccc_cache { > + /* Must be first member */ > + struct cache_coherency_ops_inst cci; > + struct mutex lock; /* Serializes SMCCC cache maintenance calls. */ > + u64 rate_limit; > +}; > + > +static int smccc_cache_status_to_errno(s32 status) > +{ > + switch (status) { > + case SMCCC_RET_SUCCESS: > + return 0; > + case SMCCC_RET_NOT_SUPPORTED: > + return -EOPNOTSUPP; > + case SMCCC_RET_INVALID_PARAMETER: > + return -EINVAL; > + case SMCCC_RET_RATE_LIMITED: > + return -EAGAIN; > + case SMCCC_RET_BUSY: > + return -EBUSY; > + default: > + return -EIO; > + } > +} > + > +static unsigned long smccc_cache_delay_us(const struct smccc_cache *cach= e) > +{ > + unsigned long delay_us =3D 0; > + > + if (cache->rate_limit) > + delay_us =3D DIV_ROUND_UP_ULL(USEC_PER_SEC, cache->rate_limit); > + > + /* > + * Firmware may not advertise a rate limit; use a small bounded backoff > + * instead of retrying in a tight loop. > + */ > + if (!delay_us) > + delay_us =3D SMCCC_CACHE_DEFAULT_DELAY_US; > + > + return min(delay_us, SMCCC_CACHE_MAX_DELAY_US); > +} > + > +static int smccc_cache_wbinv(struct cache_coherency_ops_inst *cci, > + struct cc_inval_params *invp) > +{ > + struct smccc_cache *cache =3D container_of(cci, struct smccc_cache, cci= ); > + unsigned long delay_us =3D smccc_cache_delay_us(cache); > + struct arm_smccc_res res =3D {}; > + int ret; > + > + if (!invp->size) > + return -EINVAL; > + > + /* > + * Serialize the full retry sequence. With the default bounds, a caller > + * may hold the mutex across up to five 20ms backoff sleeps. > + */ > + guard(mutex)(&cache->lock); > + > + for (unsigned int i =3D 0; i < SMCCC_CACHE_MAX_RETRIES; i++) { > + /* Long firmware operations can trigger watchdog checks. */ > + touch_nmi_watchdog(); > + > + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_CLEAN_INV_MEMREGION, > + invp->addr, invp->size, 0UL, &res); > + > + ret =3D smccc_cache_status_to_errno((s32)res.a0); > + if (!ret) > + return 0; > + > + if (ret !=3D -EBUSY && ret !=3D -EAGAIN) > + return ret; > + > + fsleep(delay_us); > + } > + > + return ret; > +} > + > +static const struct cache_coherency_ops smccc_cache_ops =3D { > + .wbinv =3D smccc_cache_wbinv, > +}; > + > +static int smccc_cache_probe(struct arm_smccc_device *sdev) > +{ > + struct arm_smccc_res res =3D {}; > + struct smccc_cache *cache; > + int ret; > + > + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_CLEAN_INV_MEMREGION_ATTRIBUTES, > + &res); > + if ((s32)res.a0) > + return -ENODEV; > + > + cache =3D cache_coherency_ops_instance_alloc(&smccc_cache_ops, > + struct smccc_cache, cci); > + if (!cache) > + return -ENOMEM; > + > + mutex_init(&cache->lock); > + cache->rate_limit =3D res.a3; > + > + ret =3D cache_coherency_ops_instance_register(&cache->cci); > + if (ret) { > + mutex_destroy(&cache->lock); > + cache_coherency_ops_instance_put(&cache->cci); > + return ret; > + } > + > + return 0; > +} > + > +static const struct arm_smccc_device_id smccc_cache_id_table[] =3D { > + { .func_id =3D ARM_SMCCC_ARCH_CLEAN_INV_MEMREGION_ATTRIBUTES }, > + {} > +}; > +MODULE_DEVICE_TABLE(arm_smccc, smccc_cache_id_table); > + > +static struct arm_smccc_driver smccc_cache_driver =3D { > + .name =3D KBUILD_MODNAME, > + .probe =3D smccc_cache_probe, > + .id_table =3D smccc_cache_id_table, > +}; > +module_arm_smccc_driver(smccc_cache_driver); > + > +MODULE_IMPORT_NS("CACHE_COHERENCY"); > +MODULE_AUTHOR("Srirangan Madhavan"); > +MODULE_DESCRIPTION("Arm SMCCC cache maintenance provider"); > +MODULE_LICENSE("GPL"); > diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smcc= c.c > index 5dc768ac4143..5a5d50d17410 100644 > --- a/drivers/firmware/smccc/smccc.c > +++ b/drivers/firmware/smccc/smccc.c > @@ -100,6 +100,11 @@ static const struct smccc_device_info smccc_devices[= ] __initconst =3D { > .requires_smc =3D true, > .device_name =3D "arm-rsi", > }, > + { > + .func_id =3D ARM_SMCCC_ARCH_CLEAN_INV_MEMREGION_ATTRIBUTES, > + .requires_smc =3D false, > + .device_name =3D "arm-smccc-cache", > + }, > }; > =20 > static bool __init smccc_probe_smccc_device(const struct smccc_device_in= fo *smccc_dev) > --=20 > 2.43.0 >=20 --fabG0ZF/qX/zSjOV Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQRh246EGq/8RLhDjO14tDGHoIJi0gUCauPVDgAKCRB4tDGHoIJi 0mfRAQCmWplBj+uJLhevvjcZpPZZVUEo3u8T6l+XEmAL47JPcgD/XT0XcZ3HQlZt DKZLu6y2ey7JrDaZXiFf98GZrWyYggk= =Sesk -----END PGP SIGNATURE----- --fabG0ZF/qX/zSjOV--