From patchwork Wed Sep 21 00:31:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12982852 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 477CCC54EE9 for ; Wed, 21 Sep 2022 00:32:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231167AbiIUAcw (ORCPT ); Tue, 20 Sep 2022 20:32:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34048 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231185AbiIUAct (ORCPT ); Tue, 20 Sep 2022 20:32:49 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 339EF792EA for ; Tue, 20 Sep 2022 17:32:47 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id br14-20020a056a00440e00b00548434985cdso2560192pfb.8 for ; Tue, 20 Sep 2022 17:32:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:reply-to:from:to:cc :subject:date; bh=YVTX41DvvKxI+UwJXy7clPsFGJGlirwL5Ozkg5cZ92g=; b=jsAJOmaw4PgLCggNnx5/TYjU6cPknBULwo8y0CP8EG2Sw1Ww/Zrcrj6rGqXRDdQXIy EWBMc+N0YIPVg9+2uIB4J+yKk6tMlcVTEVpV4JuWamxfv2EHt8Ej3zHy+5oNaS33lDfN vH0m6DcsIZmg5DI1FTeFfpS1f4mHkStL+K18cPVuWZt5XpaSJGD13ON+coD8QTFYFBT0 2meYcKf8yaGiX/cOLkiucS7uLGTg/lFhOnl9Bpa7jzJMpOV+XF1YoiuyQSMhVGmgnyon QYw+h9rG1jod+1d+oEBVHjsWVAsFeTGvZgaCNWH4jrGOsY16rCNYJVCAAf8mzBIPZVXO 9sQw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:reply-to :x-gm-message-state:from:to:cc:subject:date; bh=YVTX41DvvKxI+UwJXy7clPsFGJGlirwL5Ozkg5cZ92g=; b=jNPl3wsxHrkPEINd3pNLJ7w13kI5S92sx9urSNsyKQ5EfALsjLwxcKGDFcvEQ/gDGf aHt4vdvzACVUgZwHKTKmS6aCRykV//42FRIfJfpBGBUF7/dL9+EaJTgwjkDgWgXsvLkX pO0P05oqRoUc9WOp0gDoHGM6dD99+saqvP1daAQIsVZr/lo8z/PuCxoOZ5irjtBkcrQ/ jUSDmk/PJY507Nn31GU/1vV4o0YEZU8WTCs/d9hpwJS9l8nxujZigyBhKqkLSiiEZM8w MNjXIXbcBUI5vZaWF6V9zy7iJi4PAGiJgM7+iSd6rTG1UIs92V14Lils+7/0SKHBRq9R SJmQ== X-Gm-Message-State: ACrzQf1OsIdsyDWeKkqU6Pxf2n/+A4/3sp1SEf+PXOfdGcdCf0uoSsWO BXqP9EctWMt9VMJEtqRy86DVDDnJTvw= X-Google-Smtp-Source: AMsMyM5IXBzO0Z3bLf7U4Nl4fzPxWQVIxnXG7eLk3nZYDV6O9qarsIgEDf3VrL/1WyPiWF5/ev4wovLKs6Q= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:854:b0:542:4254:17f6 with SMTP id q20-20020a056a00085400b00542425417f6mr25988846pfk.47.1663720366656; Tue, 20 Sep 2022 17:32:46 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 21 Sep 2022 00:31:49 +0000 Mime-Version: 1.0 X-Mailer: git-send-email 2.37.3.968.ga6b4b080e4-goog Message-ID: <20220921003201.1441511-1-seanjc@google.com> Subject: [PATCH v4 00/12] KVM: x86: never write to memory from kvm_vcpu_check_block From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Sean Christopherson Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Oliver Upton , Atish Patra , David Hildenbrand , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Maxim Levitsky Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org Non-x86 folks, there's nothing interesting to see here, y'all got pulled in because removing KVM_REQ_UNHALT requires deleting kvm_clear_request() from arch code. Note, this based on: https://github.com/sean-jc/linux.git tags/kvm-x86-6.1-1 to pre-resolve conflicts with the event/exception cleanups in there. In Paolo's words... The following backtrace: [ 1355.807187] kvm_vcpu_map+0x159/0x190 [kvm] [ 1355.807628] nested_svm_vmexit+0x4c/0x7f0 [kvm_amd] [ 1355.808036] ? kvm_vcpu_block+0x54/0xa0 [kvm] [ 1355.808450] svm_check_nested_events+0x97/0x390 [kvm_amd] [ 1355.808920] kvm_check_nested_events+0x1c/0x40 [kvm] [ 1355.809396] kvm_arch_vcpu_runnable+0x4e/0x190 [kvm] [ 1355.809892] kvm_vcpu_check_block+0x4f/0x100 [kvm] [ 1355.811259] kvm_vcpu_block+0x6b/0xa0 [kvm] can occur due to kmap being called in non-sleepable (!TASK_RUNNING) context. The fix is to extend kvm_x86_ops->nested_ops.hv_timer_pending() to cover all events not already checked in kvm_arch_vcpu_is_runnable(), and then get rid of the annoying (and wrong) call to kvm_check_nested_events() from kvm_vcpu_check_block(). Beware, this is not a complete fix, because kvm_guest_apic_has_interrupt() might still _read_ memory from non-sleepable context. The fix here is probably to make kvm_arch_vcpu_is_runnable() return -EAGAIN, and in that case do a round of kvm_vcpu_check_block() polling in sleepable context. Nevertheless, it is a good start as it pushes the vmexit into vcpu_block(). The series also does a small cleanup pass on kvm_vcpu_check_block(), removing KVM_REQ_UNHALT in favor of simply calling kvm_arch_vcpu_runnable() again. Now that kvm_check_nested_events() is not called anymore by kvm_arch_vcpu_runnable(), it is much easier to see that KVM will never consume the event that caused kvm_vcpu_has_events() to return true, and therefore it is safe to evaluate it again. The alternative of propagating the return value of kvm_arch_vcpu_runnable() up to kvm_vcpu_{block,halt}() is inferior because it does not quite get right the edge cases where the vCPU becomes runnable right before schedule() or right after kvm_vcpu_check_block(). While these edge cases are unlikely to truly matter in practice, it is also pointless to get them "wrong". v4: - Make event request if INIT/SIPI is pending when GIF=>1 (SVM) and on nested VM-Enter (VMX). - Make an event request at VMXOFF iff it's necessary. - Keep the INIT/SIPI pending vs. blocked checks separate (for the above nSVM/nVMX fixes). - Check the result of kvm_check_nested_events() in vcpu_block(). - Rename INIT/SIPI helpers (hopefully we'll eventually rename all of the related collateral, e.g. "pending_events" is so misleading). - Drop pending INIT/SIPI snaphsot to avoid creating weird, conflicting code when kvm_check_nested_events() is called by vcpu_block(). v3: - https://lore.kernel.org/all/20220822170659.2527086-1-pbonzini@redhat.com - do not propagate the return value of kvm_arch_vcpu_runnable() up to kvm_vcpu_{block,halt}() - move and reformat the comment in vcpu_block() move KVM_REQ_UNHALT removal last Paolo Bonzini (5): KVM: x86: make vendor code check for all nested events KVM: x86: lapic does not have to process INIT if it is blocked KVM: x86: never write to memory from kvm_vcpu_check_block() KVM: mips, x86: do not rely on KVM_REQ_UNHALT KVM: remove KVM_REQ_UNHALT Sean Christopherson (7): KVM: nVMX: Make an event request when pending an MTF nested VM-Exit KVM: x86: Rename and expose helper to detect if INIT/SIPI are allowed KVM: x86: Rename kvm_apic_has_events() to make it INIT/SIPI specific KVM: SVM: Make an event request if INIT or SIPI is pending when GIF is set KVM: nVMX: Make an event request if INIT or SIPI is pending on VM-Enter KVM: nVMX: Make event request on VMXOFF iff INIT/SIPI is pending KVM: x86: Don't snapshot pending INIT/SIPI prior to checking nested events Documentation/virt/kvm/vcpu-requests.rst | 28 +-------------- arch/arm64/kvm/arm.c | 1 - arch/mips/kvm/emulate.c | 6 ++-- arch/powerpc/kvm/book3s_pr.c | 1 - arch/powerpc/kvm/book3s_pr_papr.c | 1 - arch/powerpc/kvm/booke.c | 1 - arch/powerpc/kvm/powerpc.c | 1 - arch/riscv/kvm/vcpu_insn.c | 1 - arch/s390/kvm/kvm-s390.c | 2 -- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/lapic.c | 38 ++++++-------------- arch/x86/kvm/lapic.h | 9 ++++- arch/x86/kvm/svm/svm.c | 3 +- arch/x86/kvm/vmx/nested.c | 33 +++++++++-------- arch/x86/kvm/vmx/vmx.c | 6 ++-- arch/x86/kvm/x86.c | 46 +++++++++++++++--------- arch/x86/kvm/x86.h | 5 --- arch/x86/kvm/xen.c | 1 - include/linux/kvm_host.h | 3 +- virt/kvm/kvm_main.c | 4 +-- 20 files changed, 79 insertions(+), 113 deletions(-) base-commit: 5df50a4a9b60afba4dd2be76d0f0fb8ae8c9beab