From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794047379; b=YkB5t7hHwthGXVOWH2X8u2YxLSIqUNFiuHWz8WjDOhoLng1QjWVpisxu6EZvMuTXrdWd GHQomIybE6UFmf2knUodHh34/IJyh3fzfht4jy+F+iEGMu4lTIWIg6+zz0wNutwYGE+WL Q2utVIB/S/QNsU0k1GE0QJBrFvRiGnPs/xKrgrTvD2vXtr8GcS4evEpFVC44oh4CA/hhu EReaf+qzeeJ8S1tv3rpNvM5R6fDN4SqH+dNu5ByO4lJ2SWqesCrF+FURQHwSKRXAP5TCQ 0zlx7jJsGCtJEUw0QjMo6rFzj2gzTFIzdECRtD/C1VgHTVOugPhpCcUUK2fMPpOyLiA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047379; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=O74uCKpOe+6OoO31YB0GQPdwRG2W/Ag54k+mFOEL9FI=; b=D4ZS6QHZ8871k2lVkNDyVM0dqhj1dGnagqSq84y62dm8VlW664Z+0elpaBxEaVKnTddL vzlXOD3odbfi7ydqe7w2MbLcUxUaJFw75JPG7mZaFSZsK5byJCDniHKoipnLFKeAHz4Q8 2RPSDcBOfVTm2IwP7wxG0V53XaZIt2Yf3wHQ41jkg35sGPcS8T61+CAgmzVT/xSdkvO5J UQFi6xEt3+pXk3QjhngG8XOHU7OyNOVL/a+rOLc5jeIUkbU/vkzwg3eCBmUNefhLvHhWQ Ks/Apxvv62qNIBqu4gmFff8ES9yBlDmBVBZ7tRYA3cujbr/v99u2A99mps4Ezgkta2A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AceVjbvd; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id AA391606A326 for ; Sat, 7 Nov 2026 10:29:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=AceVjbvd Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1127B1F0089F; Sat, 7 Nov 2026 10:29:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047378; bh=O74uCKpOe+6OoO31YB0GQPdwRG2W/Ag54k+mFOEL9FI=; h=From:To:Cc:Subject:Date; b=AceVjbvdOljQpeF/89hr1yqH3zozqMDTR0mK5VxQiSh05+VHU4o9cvIKNW20Qhv/N B7D42KB9Xxhb6w66EIEOlS4nR87lejs8LCPckjAduiSdnnfaFWK31lO6kueZFTSckn Jhxyb2r4o8NkXJ+9aSSEQnqKPxSfmGAZLAcdF4eXQ3iF2uNkDFKCxY8RQtiBZUg2TM mA0qYKSba+nnRjaIcEKT4JSDErsbhM0dKKFzoJ/sWKdN5f156YaMNw+VmC6IFVx14U GX6aLqI/cgSzET4G5MeNWCHgynKpwI1gLBmdS2utan7sfyU36WMR4cDll0xkCFzfxI MQccRpJ9Gy0Tw== From: Sasha Levin To: christian.loehle@arm.com, sumitg@nvidia.com, rafael.j.wysocki@intel.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] ACPI: CPPC: Propagate errors from cross-CPU FFH calls" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:29:37 -0500 Message-ID: <20261107052937-failed-6.6-36e96b469da2@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 36e96b469da24868f727b4cd168d7cf01cbd163d # git commit -s git send-email --to '' --in-reply-to '20261107052937-failed-6.6-36e96b469da2@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 36e96b469da24868f727b4cd168d7cf01cbd163d Mon Sep 17 00:00:00 2001 From: Christian Loehle Date: Wed, 16 Sep 2026 17:28:02 +0100 Subject: [PATCH] ACPI: CPPC: Propagate errors from cross-CPU FFH calls The arm64 and RISC-V CPPC FFH accessors ignore the return value of smp_call_function_single(). If the target CPU is offline, the call can return -ENXIO without running the callback. The accessors then consume callback output which was never initialized and may report success. CPU offlining leaves the CPU's CPPC sysfs attributes present. On arm64, the AMU feature mask does not exclude an offline CPU, so a paired counter read can expose uninitialized stack values through feedback_ctrs. RISC-V has the same problem in both SBI and CSR reads, and its write paths also inspect an uninitialized callback status after a failed cross-CPU call. Return the SMP call error before using callback output. The arm64 single and paired counter readers already check the helper's return value. For RISC-V, also check the callback status before copying a read value: an unsupported CSR sets the error but does not initialize the value. Fixes: 68c5debcc06d ("arm64: implement CPPC FFH support using AMUs") Fixes: 30f3ffbee86b ("ACPI: RISC-V: Add CPPC driver") Cc: All applicable Signed-off-by: Christian Loehle Tested-by: Sumit Gupta Link: https://patch.msgid.link/20260916162805.1039247-18-christian.loehle@arm.com Signed-off-by: Rafael J. Wysocki --- arch/arm64/kernel/topology.c | 2 +- drivers/acpi/riscv/cppc.c | 26 ++++++++++++++++++++------ 2 files changed, 21 insertions(+), 7 deletions(-) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 2c030e78d5e45..55bd8fa3e95cf 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -427,7 +427,7 @@ int counters_read_on_cpu(int cpu, smp_call_func_t func, void *val) return -EPERM; func(val); } else { - smp_call_function_single(cpu, func, val, 1); + return smp_call_function_single(cpu, func, val, 1); } return 0; diff --git a/drivers/acpi/riscv/cppc.c b/drivers/acpi/riscv/cppc.c index 42c1a90524707..4ea4ddedd91f1 100644 --- a/drivers/acpi/riscv/cppc.c +++ b/drivers/acpi/riscv/cppc.c @@ -97,6 +97,7 @@ bool cpc_ffh_supported(void) int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val) { struct sbi_cppc_data data; + int ret; if (WARN_ON_ONCE(irqs_disabled())) return -EPERM; @@ -107,19 +108,27 @@ int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val) data.reg = FFH_CPPC_SBI_REG(reg->address); - smp_call_function_single(cpu, sbi_cppc_read, &data, 1); + ret = smp_call_function_single(cpu, sbi_cppc_read, &data, 1); + if (ret) + return ret; + if (data.ret.error) + return sbi_err_map_linux_errno(data.ret.error); *val = data.ret.value; - return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0; + return 0; } else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) { data.reg = FFH_CPPC_CSR_NUM(reg->address); - smp_call_function_single(cpu, cppc_ffh_csr_read, &data, 1); + ret = smp_call_function_single(cpu, cppc_ffh_csr_read, &data, 1); + if (ret) + return ret; + if (data.ret.error) + return data.ret.error; *val = data.ret.value; - return data.ret.error; + return 0; } return -EINVAL; @@ -128,6 +137,7 @@ int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val) int cpc_write_ffh(int cpu, struct cpc_reg *reg, u64 val) { struct sbi_cppc_data data; + int ret; if (WARN_ON_ONCE(irqs_disabled())) return -EPERM; @@ -139,14 +149,18 @@ int cpc_write_ffh(int cpu, struct cpc_reg *reg, u64 val) data.reg = FFH_CPPC_SBI_REG(reg->address); data.val = val; - smp_call_function_single(cpu, sbi_cppc_write, &data, 1); + ret = smp_call_function_single(cpu, sbi_cppc_write, &data, 1); + if (ret) + return ret; return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0; } else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) { data.reg = FFH_CPPC_CSR_NUM(reg->address); data.val = val; - smp_call_function_single(cpu, cppc_ffh_csr_write, &data, 1); + ret = smp_call_function_single(cpu, cppc_ffh_csr_write, &data, 1); + if (ret) + return ret; return data.ret.error; } -- 2.53.0