From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29EEEC00140 for ; Fri, 5 Aug 2022 19:40:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241284AbiHETks (ORCPT ); Fri, 5 Aug 2022 15:40:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238395AbiHETkr (ORCPT ); Fri, 5 Aug 2022 15:40:47 -0400 Received: from mail-lf1-x12c.google.com (mail-lf1-x12c.google.com [IPv6:2a00:1450:4864:20::12c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9B5EE11451 for ; Fri, 5 Aug 2022 12:40:45 -0700 (PDT) Received: by mail-lf1-x12c.google.com with SMTP id e15so4840680lfs.0 for ; Fri, 05 Aug 2022 12:40:45 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=semihalf.com; s=google; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc; bh=rty6mPaEYkYj+hk2AIwEoGnTyks1fl0dWOatixd39IQ=; b=ZVdfbFAYeIUhGFL1MsmiiKPKr/iDRfw7LNLWovNYdZMMSqGycmpqxqzuBFS59yToBK MPF47XlwvkHwloFZ0QU+WvcrJW+xDfoqtCH6+uSUqgYSW2NOjGo2det5Od7Njoq5Ml6/ +CwAoGIa929cRNttmpn9qxEz7B25vEtt9azLRc4iOHcQBoQNErztOE3hjKnLTHyzGigl 4mvtAuLzu+sJRNekNhuKmQSjb7IotNHEnum47KHJxbGqltNqRcXB5U3smOfpln9CRsBE QX1tQ+doOlI35hmgOmUSmYGQtWtHtzm0jO8ApsmID8pbklD+AmnrFFEawPFrZlRm05Ee pU5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc; bh=rty6mPaEYkYj+hk2AIwEoGnTyks1fl0dWOatixd39IQ=; b=zox1oxlzW5iUjyu3GXO5Twbwp0itBSEzcKXljIOfgy2uQpuu+BXSiIJw7I9tK2JhCm 4WppHeBWqz/052vSUW0GSuJcTqWCWS9hM/XmzrcwSY6yDM1KU1DLWjhLJ9vCihFo+2Uy 5+jx2yGIjcZ84LRbNCC5wx8wNSF2QVmbU7cDptG2aAhlTUyMb0kcEf84UY81Tgt8T2UX FttFo2J21ZeyMi0XNZJnbZqeJcPPQT92HulGucZFTiCWROIYl/0i/xaMBbabuiQMQo0d LOCBsBjdbDUVTriHRCgCjnT3341EnosMUIIQyRlTD0vxXeFk7VDu3r0O3xWt9YwFex8N 5VIw== X-Gm-Message-State: ACgBeo1Qdzx4bq/ksITOPF5ObR2YfczSIIO6TFRG7KTjIWRdsmFh8O53 Q8qol8Y/oq5pMBEtEm+lI0SCvw== X-Google-Smtp-Source: AA6agR4yyOputGlNoeiiinUA89rWH8MyQHy5pMHZ5HQQAH93EmzS4UkCpxA03zHmJI4OgjW4LGuxNA== X-Received: by 2002:a05:6512:3981:b0:48a:6fb9:74b7 with SMTP id j1-20020a056512398100b0048a6fb974b7mr2647305lfu.98.1659728443958; Fri, 05 Aug 2022 12:40:43 -0700 (PDT) Received: from dmaluka.office.semihalf.net ([83.142.187.84]) by smtp.gmail.com with ESMTPSA id o4-20020a056512230400b0048a407f41bbsm560079lfu.238.2022.08.05.12.40.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Aug 2022 12:40:43 -0700 (PDT) From: Dmytro Maluka To: Sean Christopherson , Paolo Bonzini , kvm@vger.kernel.org Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org, Eric Auger , Alex Williamson , Rong L Liu , Zhenyu Wang , Tomasz Nowicki , Grzegorz Jaszczyk , upstream@semihalf.com, Dmitry Torokhov , Dmytro Maluka Subject: [PATCH v2 0/5] KVM: Fix oneshot interrupts forwarding Date: Fri, 5 Aug 2022 21:39:14 +0200 Message-Id: <20220805193919.1470653-1-dmy@semihalf.com> X-Mailer: git-send-email 2.37.1.559.g78731f0fdb-goog MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The existing KVM mechanism for forwarding of level-triggered interrupts using resample eventfd doesn't work quite correctly in the case of interrupts that are handled in a Linux guest as oneshot interrupts (IRQF_ONESHOT). Such an interrupt is acked to the device in its threaded irq handler, i.e. later than it is acked to the interrupt controller (EOI at the end of hardirq), not earlier. The existing KVM code doesn't take that into account, which results in erroneous extra interrupts in the guest caused by premature re-assert of an unacknowledged IRQ by the host. This patch series fixes this issue (for now on x86 only) by checking if the interrupt is unmasked when we receive irq ack (EOI) and, in case if it's masked, postponing resamplefd notify until the guest unmasks it. Patches 1 and 2 extend the existing support for irq mask notifiers in KVM, which is a prerequisite needed for KVM irqfd to use mask notifiers to know when an interrupt is masked or unmasked. Patch 3 implements the actual fix: postponing resamplefd notify in irqfd until the irq is unmasked. Patches 4 and 5 just do some optional renaming for consistency, as we are now using irq mask notifiers in irqfd along with irq ack notifiers. Please see individual patches for more details. v2: - Fixed compilation failure on non-x86: mask_notifier_list moved from x86 "struct kvm_arch" to generic "struct kvm". - kvm_fire_mask_notifiers() also moved from x86 to generic code, even though it is not called on other architectures for now. - Instead of kvm_irq_is_masked() implemented kvm_register_and_fire_irq_mask_notifier() to fix potential race when reading the initial IRQ mask state. - Renamed for clarity: - irqfd_resampler_mask() -> irqfd_resampler_mask_notify() - kvm_irq_has_notifier() -> kvm_irq_has_ack_notifier() - resampler->notifier -> resampler->ack_notifier - Reorganized code in irqfd_resampler_ack() and irqfd_resampler_mask_notify() to make it easier to follow. - Don't follow unwanted "return type on separate line" style for irqfd_resampler_mask_notify(). Dmytro Maluka (5): KVM: x86: Move irq mask notifiers from x86 to generic KVM KVM: x86: Add kvm_register_and_fire_irq_mask_notifier() KVM: irqfd: Postpone resamplefd notify for oneshot interrupts KVM: irqfd: Rename resampler->notifier KVM: Rename kvm_irq_has_notifier() arch/x86/include/asm/kvm_host.h | 17 +--- arch/x86/kvm/i8259.c | 6 ++ arch/x86/kvm/ioapic.c | 8 +- arch/x86/kvm/ioapic.h | 1 + arch/x86/kvm/irq_comm.c | 74 +++++++++++------ arch/x86/kvm/x86.c | 1 - include/linux/kvm_host.h | 21 ++++- include/linux/kvm_irqfd.h | 16 +++- virt/kvm/eventfd.c | 136 ++++++++++++++++++++++++++++---- virt/kvm/kvm_main.c | 1 + 10 files changed, 221 insertions(+), 60 deletions(-) -- 2.37.1.559.g78731f0fdb-goog