From patchwork Thu Oct 3 03:53:31 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Kelley X-Patchwork-Id: 13820654 X-Patchwork-Delegate: kuba@kernel.org Received: from mail-pl1-f171.google.com (mail-pl1-f171.google.com [209.85.214.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 52D86537F8; Thu, 3 Oct 2024 03:54:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.171 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727927657; cv=none; b=NcgKf+IJ1H9R4TsKdPMLIrxijxjDjh3f9hEAQBwKl/Tmt1oP1SmgsYvMdJptfvS+Pgp3mEwSaA4rTJz6XqGUSg7zacSDT2Yz1wUXpnL6l5DICbJQLmlogAQlF6L9L4ckHL4zNdSAqAQH2+8RD7IJ/RVbafGLPLIxDYIz38fJXvc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727927657; c=relaxed/simple; bh=mHoaQT1JoyG6LkyzWkFbXUPdVaWzkJTm5hCach2QWbM=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=TxVLtz9B0IHJp3B0j9epa0c6W9EtOQ0sMagg0RVndyqczLf6FzCbZleOdAC4C2pykkmnFIyIQWXiEZNqz4w6ALVCchbXKJnCQc7i3XQqg78FHD316aig9nxKBzUbr4a7CQufwviTfpj/yAXjVdoxmL4A8wjUDcYGp57oT0pGL28= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=hk+PR3RD; arc=none smtp.client-ip=209.85.214.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="hk+PR3RD" Received: by mail-pl1-f171.google.com with SMTP id d9443c01a7336-20ba6b39a78so3016695ad.3; Wed, 02 Oct 2024 20:54:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1727927655; x=1728532455; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:from:to:cc:subject :date:message-id:reply-to; bh=tDuFxybHODEaeVrwvh+oodf/QVAaDeDVDDTRMXteliU=; b=hk+PR3RDdJxOiqwo2fJLWdB8qDPiHpmfoy+oJJnQoc3qFUTP/w4iwXI6XHddMNDYgu dpTmIHOyEo/iWJooCaUcbyAUeKeLL3CLwobxSVIZn/9G+yO2lxE9dups8UmHoci/8baC tZ62+ffRbBN4wL5Ij/nKxPH39Vn6SaYn17uwLsHXv+jSfXKHB1sh4/Bm9FAi0F71ajLR 3XIDW2m5QdlHZupiwRzXd+NNkA9wn4ZOscPCZsAeIYRTlT61guGmmCSuC1d2NG6qy8G9 IrjvrMCOYuiEYcHKXOSvv3wSrkGilIkPgjXRbzzCvSWjlM+OJzIZ416OPUMyzQDncOqM TzaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727927655; x=1728532455; h=content-transfer-encoding:mime-version:reply-to:references :in-reply-to:message-id:date:subject:cc:to:from:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=tDuFxybHODEaeVrwvh+oodf/QVAaDeDVDDTRMXteliU=; b=sHM8qs6ZBbf+kzBLeEdrobG1QlN2RBCL9p+ZU9OmdNwkc12FQALnZyqyyqKNZ82Gh1 tyhfZAmpK9kVMXgOjAKDQRc+RLYhb+Kcw8VSad8grRgRIv93WhKMO8pXNyGVo1SKu3LG PK0Hy2NA4CRkAMjA+2NYqQplibxYjpxZWg1VJ0b9Ux1DtjzWtdv2PZ01yENwFvy9dmF3 L+78rzjrZNDk7buFzJI4RuAXhnrVBx94fvpwtdw3+HIo3Rkd/sXwleBT17zGEbmMFasF sGwy2M8tL3cP/d/UgkkSbxGToCN9xZrMpqlACSSICowQCv74iqFMt37me1hMnUYnfXeD blEw== X-Forwarded-Encrypted: i=1; AJvYcCW/V4goKU2joEQ0H4ZRvMEssmPj2zVV5gLbC895qP11E1Dllu51POaaroL2h9IogwpPAVNZgHYg@vger.kernel.org, AJvYcCX/L5uiqGTEmxDiv2cgu+SsiaYdVNhZwcx2NmUCWoHDqxPcvTiK1osgBm/S38q72uvPDfHN+PD6Ktvb+dw=@vger.kernel.org, AJvYcCXmagrxil7bE/HWovt/4vK2TAp2kcaN8YNaQRDJ+mRMHxH7ncyQTm95vLuoSL1LrY3lzr4TnwcZsjIqlbQb@vger.kernel.org, AJvYcCXp0UHnpTqFZPBZb6rFAvuWNGoNvZygtsQ+h9ZD+llv30/rS2nk7Ysg3o3AEYlBDclQRHdG9SookKkY3Q==@vger.kernel.org X-Gm-Message-State: AOJu0YxAmob5gej3qWrUSnabFSety0cLRqytGq/sv1QubshNaXZKRaFK aIk6CCXl5Kcsd8GY4wt4aTyBTD7Zz5ZFgfiyUpeSOfJN3+xNctLN X-Google-Smtp-Source: AGHT+IFKLPlcSp9SUFRml4GIrUDRe7i+pHx0/lLBWbzLd4R0zTcKVcErbP/p5ZwNke1aAWlNDTBqqg== X-Received: by 2002:a17:903:c5:b0:20b:a431:8f2f with SMTP id d9443c01a7336-20bc5a701bbmr52713415ad.55.1727927655583; Wed, 02 Oct 2024 20:54:15 -0700 (PDT) Received: from localhost.localdomain (c-67-160-120-253.hsd1.wa.comcast.net. [67.160.120.253]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-20beead8dc2sm906115ad.44.2024.10.02.20.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Oct 2024 20:54:15 -0700 (PDT) From: mhkelley58@gmail.com X-Google-Original-From: mhklinux@outlook.com To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, joro@8bytes.org, will@kernel.org, robin.murphy@arm.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, James.Bottomley@HansenPartnership.com, martin.petersen@oracle.com Cc: iommu@lists.linux.dev, netdev@vger.kernel.org, linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Subject: [PATCH 3/5] iommu/hyper-v: Don't assume cpu_possible_mask is dense Date: Wed, 2 Oct 2024 20:53:31 -0700 Message-Id: <20241003035333.49261-4-mhklinux@outlook.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20241003035333.49261-1-mhklinux@outlook.com> References: <20241003035333.49261-1-mhklinux@outlook.com> Reply-To: mhklinux@outlook.com Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Michael Kelley Current code gets the APIC IDs for CPUs numbered 255 and lower. This code assumes cpu_possible_mask is dense, which is not true in the general case per [1]. If cpu_possible_mask contains holes, num_possible_cpus() is less than nr_cpu_ids, so some CPUs might get skipped. Furthermore, getting the APIC ID of a CPU that isn't in cpu_possible_mask is invalid. However, the configurations that Hyper-V provides to guest VMs on x86 hardware, in combination with how x86 code assigns Linux CPU numbers, *does* always produce a dense cpu_possible_mask. So the dense assumption is not currently causing failures. But for robustness against future changes in how cpu_possible_mask is populated, update the code to no longer assume dense. The correct approach is to determine the range to scan based on nr_cpu_ids, and skip any CPUs that are not in the cpu_possible_mask. [1] https://lore.kernel.org/lkml/SN6PR02MB4157210CC36B2593F8572E5ED4692@SN6PR02MB4157.namprd02.prod.outlook.com/ Signed-off-by: Michael Kelley --- drivers/iommu/hyperv-iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/hyperv-iommu.c b/drivers/iommu/hyperv-iommu.c index 8a5c17b97310..2a86aa5d54c6 100644 --- a/drivers/iommu/hyperv-iommu.c +++ b/drivers/iommu/hyperv-iommu.c @@ -164,8 +164,8 @@ static int __init hyperv_prepare_irq_remapping(void) * max cpu affinity for IOAPIC irqs. Scan cpu 0-255 and set cpu * into ioapic_max_cpumask if its APIC ID is less than 256. */ - for (i = min_t(unsigned int, num_possible_cpus() - 1, 255); i >= 0; i--) - if (cpu_physical_id(i) < 256) + for (i = min_t(unsigned int, nr_cpu_ids - 1, 255); i >= 0; i--) + if (cpu_possible(i) && cpu_physical_id(i) < 256) cpumask_set_cpu(i, &ioapic_max_cpumask); return 0;