From nobody Fri Dec 19 20:40:15 2025 Received: from xry111.site (xry111.site [89.208.246.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DAED6233706 for ; Fri, 16 May 2025 10:26:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=89.208.246.23 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747391200; cv=none; b=R6i/tpJabi5lc3MP30M53fIQitgje8zJCqlZNoWlt2kSvCYVnAJP+Vnfyr03uqf5Pb/ZlYPF21fFo/MVffiHm1jWHTqylBxourhqhAHcmeAfOog+tClURmL8aQj2aX3+Z7V2uiRQoFieqcDX8LI7Mw2xHQVMbXFe4/soyGwn44I= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747391200; c=relaxed/simple; bh=E2l1wYv0Wpw+TMqnem12bJIKNZtxIm4iVCgykL/fztU=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=C2KaU77+AOVAnWCoH850Z//qLpurEMJs1hJPIEKNj9SqF1C0SABKYjY6w3Civ20UNfFNcYfkrfpNKZw2LEV01Vpcx7AWcHKpSvNfyhsVvQpbk0KNfh10i9ftE0XiwrQrswv/GnfssGiQ+7GSA6nK+pkmfQRlCoHWkUIQaXoXYUU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site; spf=pass smtp.mailfrom=xry111.site; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b=FHI8037C; arc=none smtp.client-ip=89.208.246.23 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=xry111.site Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xry111.site Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=xry111.site header.i=@xry111.site header.b="FHI8037C" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xry111.site; s=default; t=1747391189; bh=6i59xOsB2P1poB0rSQ5FPpBfoLh4uAEDe2LmcbwelDg=; h=From:To:Cc:Subject:Date:From; b=FHI8037Cbd3vejQlthmvBYBGSCM0cKrF0FoXmevvW73Q/D2YSXURyNIiv8b13IP9O xMY2srcR9H5V4rftjfpLk45pGQKHxPtIUUPQVTuLkG+VRj70j3Yj8aNlvF81vxNhsG N8Z7rZYFrAoL6uODytsqsp+6XFnIjvmmkhKAVNbg= Received: from stargazer.. (unknown [IPv6:240e:457:1000:4d1d:620b:9b2:5a59:f0a1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (secp384r1) server-digest SHA384) (Client did not present a certificate) (Authenticated sender: xry111@xry111.site) by xry111.site (Postfix) with ESMTPSA id 400A265F62; Fri, 16 May 2025 06:26:21 -0400 (EDT) From: Xi Ruoyao To: James Morse , Marc Zyngier , Anshuman Khandual , Ben Horgan Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Shameer Kolothum , Mingcong Bai , Xi Ruoyao , Shaopeng Tan Subject: [PATCH v3] arm64: Add override for MPAM Date: Fri, 16 May 2025 18:25:56 +0800 Message-ID: <20250516102556.9688-1-xry111@xry111.site> X-Mailer: git-send-email 2.49.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" As the message of the commit 09e6b306f3ba ("arm64: cpufeature: discover CPU support for MPAM") already states, if a buggy firmware fails to either enable MPAM or emulate the trap as if it were disabled, the kernel will just fail to boot. While upgrading the firmware should be the best solution, we have some hardware of which the vendor have made no response 2 months after we requested a firmware update. Allow overriding it so our devices don't become some e-waste. Cc: James Morse Cc: Marc Zyngier Cc: Shameer Kolothum Cc: Mingcong Bai Tested-by: Shaopeng Tan Tested-by: Ben Horgan Signed-off-by: Xi Ruoyao --- [v2]->v3: - Fix typos in the subject and a comment. - Remove a useless #include directive. [v1]->v2: - Handle the override and initialize EL2 mpam in finalise_el2_state - Move info->mpamidr assignment to {init,update}_cpu_features [v1]: https://lore.kernel.org/linux-arm-kernel/20250401055650.22542-1-xry11= 1@xry111.site/ .../admin-guide/kernel-parameters.txt | 3 +++ arch/arm64/include/asm/el2_setup.h | 24 ++++++++----------- arch/arm64/kernel/cpufeature.c | 7 ++++-- arch/arm64/kernel/cpuinfo.c | 7 ++++-- arch/arm64/kernel/pi/idreg-override.c | 2 ++ 5 files changed, 25 insertions(+), 18 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 8f75ec177399..0bfcbeab7a3b 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -458,6 +458,9 @@ arm64.nomops [ARM64] Unconditionally disable Memory Copy and Memory Set instructions support =20 + arm64.nompam [ARM64] Unconditionally disable Memory Partitioning And + Monitoring support + arm64.nomte [ARM64] Unconditionally disable Memory Tagging Extension support =20 diff --git a/arch/arm64/include/asm/el2_setup.h b/arch/arm64/include/asm/el= 2_setup.h index d40e427ddad9..2e6b9086efc5 100644 --- a/arch/arm64/include/asm/el2_setup.h +++ b/arch/arm64/include/asm/el2_setup.h @@ -294,19 +294,6 @@ .Lskip_gcs_\@: .endm =20 -.macro __init_el2_mpam - /* Memory Partitioning And Monitoring: disable EL2 traps */ - mrs x1, id_aa64pfr0_el1 - ubfx x0, x1, #ID_AA64PFR0_EL1_MPAM_SHIFT, #4 - cbz x0, .Lskip_mpam_\@ // skip if no MPAM - msr_s SYS_MPAM2_EL2, xzr // use the default partition - // and disable lower traps - mrs_s x0, SYS_MPAMIDR_EL1 - tbz x0, #MPAMIDR_EL1_HAS_HCR_SHIFT, .Lskip_mpam_\@ // skip if no MPAMHCR = reg - msr_s SYS_MPAMHCR_EL2, xzr // clear TRAP_MPAMIDR_EL1 -> EL2 -.Lskip_mpam_\@: -.endm - /** * Initialize EL2 registers to sane values. This should be called early on= all * cores that were booted in EL2. Note that everything gets initialised as @@ -324,7 +311,6 @@ __init_el2_stage2 __init_el2_gicv3 __init_el2_hstr - __init_el2_mpam __init_el2_nvhe_idregs __init_el2_cptr __init_el2_fgt @@ -371,6 +357,16 @@ #endif =20 .macro finalise_el2_state + check_override id_aa64pfr0, ID_AA64PFR0_EL1_MPAM_SHIFT, .Linit_mpam_\@, .= Lskip_mpam_\@, x1, x2 + +.Linit_mpam_\@: + msr_s SYS_MPAM2_EL2, xzr // use the default partition + // and disable lower traps + mrs_s x0, SYS_MPAMIDR_EL1 + tbz x0, #MPAMIDR_EL1_HAS_HCR_SHIFT, .Lskip_mpam_\@ // skip if no MPAMHCR= reg + msr_s SYS_MPAMHCR_EL2, xzr // clear TRAP_MPAMIDR_EL1 -> EL2 + +.Lskip_mpam_\@: check_override id_aa64pfr0, ID_AA64PFR0_EL1_SVE_SHIFT, .Linit_sve_\@, .Ls= kip_sve_\@, x1, x2 =20 .Linit_sve_\@: /* SVE register access */ diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c index 4c46d80aa64b..7b8c998a0466 100644 --- a/arch/arm64/kernel/cpufeature.c +++ b/arch/arm64/kernel/cpufeature.c @@ -1198,8 +1198,10 @@ void __init init_cpu_features(struct cpuinfo_arm64 *= info) cpacr_restore(cpacr); } =20 - if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) + if (id_aa64pfr0_mpam(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) { + info->reg_mpamidr =3D read_cpuid(MPAMIDR_EL1); init_cpu_ftr_reg(SYS_MPAMIDR_EL1, info->reg_mpamidr); + } =20 if (id_aa64pfr1_mte(info->reg_id_aa64pfr1)) init_cpu_ftr_reg(SYS_GMID_EL1, info->reg_gmid); @@ -1450,7 +1452,8 @@ void update_cpu_features(int cpu, cpacr_restore(cpacr); } =20 - if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) { + if (id_aa64pfr0_mpam(read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1))) { + info->reg_mpamidr =3D read_cpuid(MPAMIDR_EL1); taint |=3D check_update_ftr_reg(SYS_MPAMIDR_EL1, cpu, info->reg_mpamidr, boot->reg_mpamidr); } diff --git a/arch/arm64/kernel/cpuinfo.c b/arch/arm64/kernel/cpuinfo.c index 285d7d538342..15d39fbc6085 100644 --- a/arch/arm64/kernel/cpuinfo.c +++ b/arch/arm64/kernel/cpuinfo.c @@ -494,8 +494,11 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *= info) if (id_aa64pfr0_32bit_el0(info->reg_id_aa64pfr0)) __cpuinfo_store_cpu_32bit(&info->aarch32); =20 - if (id_aa64pfr0_mpam(info->reg_id_aa64pfr0)) - info->reg_mpamidr =3D read_cpuid(MPAMIDR_EL1); + /* + * info->reg_mpamidr deferred to {init,update}_cpu_features because we + * don't want to read it (and trigger a trap on buggy firmware) if + * using an aa64pfr0_el1 override to unconditionally disable MPAM. + */ =20 if (IS_ENABLED(CONFIG_ARM64_SME) && id_aa64pfr1_sme(info->reg_id_aa64pfr1)) { diff --git a/arch/arm64/kernel/pi/idreg-override.c b/arch/arm64/kernel/pi/i= dreg-override.c index c6b185b885f7..836e5a9b98d0 100644 --- a/arch/arm64/kernel/pi/idreg-override.c +++ b/arch/arm64/kernel/pi/idreg-override.c @@ -127,6 +127,7 @@ static const struct ftr_set_desc pfr0 __prel64_initcons= t =3D { .fields =3D { FIELD("sve", ID_AA64PFR0_EL1_SVE_SHIFT, pfr0_sve_filter), FIELD("el0", ID_AA64PFR0_EL1_EL0_SHIFT, NULL), + FIELD("mpam", ID_AA64PFR0_EL1_MPAM_SHIFT, NULL), {} }, }; @@ -246,6 +247,7 @@ static const struct { { "rodata=3Doff", "arm64_sw.rodataoff=3D1" }, { "arm64.nolva", "id_aa64mmfr2.varange=3D0" }, { "arm64.no32bit_el0", "id_aa64pfr0.el0=3D1" }, + { "arm64.nompam", "id_aa64pfr0.mpam=3D0" }, }; =20 static int __init parse_hexdigit(const char *p, u64 *v) --=20 2.49.0