From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 155BB3D38B for ; Fri, 27 Oct 2023 18:22:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="3xT/ci44" Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 550FA18F for ; Fri, 27 Oct 2023 11:22:48 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id d9443c01a7336-1cc29f3afe0so4664925ad.2 for ; Fri, 27 Oct 2023 11:22:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698430967; x=1699035767; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=fLrd3AGy66HdihfPmI58EyyG3FCGELBv0TZMEZAIG4Y=; b=3xT/ci44KKzjmmrpAao7ngJthUkPCvXpRnXckArfxBa8Zr2fJkiV/GGCTxm0vyYgnh vv6yfcs4BneSBQUXt/mB0YsqyBZ5wbzwqFoo9Bod2Vk1MyjcsTDxUyOaqvrVCPcPa38Q 32ttnMXcYZbWGrhfz3tqW/C/cXNeWarTxG3N24uN5SnPll/wesBAT3TLmemoDU1LtMo5 WiucU7uTpzEHtyi7rLFqaOet9e3z0o/w1AOA4cn6qjtbOCIhZzZy910UQftKJeSXkd57 vmfr68Fie5ywyab18IL2u0ebB08b0G3NaN81dOAHYtcfnhwyH5rgn4AzwmqQ41JLdjya AovQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698430967; x=1699035767; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=fLrd3AGy66HdihfPmI58EyyG3FCGELBv0TZMEZAIG4Y=; b=Qra7TmxV1r877iB4Pkvnolhhpd6ZZea3P2f+wrUKy6f5mTl+QCP6rEuVbnXBGZV3qX sPGq0pohcjiOlblWyHgLM3SqRCtqizO1tSSj5+FQpUFYa0KRwckTRpTPr5qGYP4n76ux d+CFra2lwi/2sTbtDCvE11WIb1qOdv/nBRe27zjApShVQKbmRJd9j650XtYl53rHWGY0 jumYRHXIMiOtu/g3BWSMQeLvUnWklo9T+dysnuJUzqKhsB7+3Q9jzBWfms35nyBGbPsL Q5EeF45HNosfwASzIR42m0R+ONhHWPs8m2h6XDsDLSGeQQOiXyzoIUH0wiMmKrOZRutM 8daA== X-Gm-Message-State: AOJu0YzV1rabRQ3x1TzsqOQwmlnqK0iEIyq94Ju2C6sxjpr41dSnus0b Td4DPLMDvxgF7FaFTg3g3t1PfyOqOH8= X-Google-Smtp-Source: AGHT+IFw7CMiVxkdfLmPKgztX5f1RnQlL4BTlZlVKLxMz6aRVtHUrQY578kvMdkjnRTl6BBw2VS25sQYIRo= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:902:ee14:b0:1ca:b952:f5fa with SMTP id z20-20020a170902ee1400b001cab952f5famr63161plb.5.1698430967325; Fri, 27 Oct 2023 11:22:47 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 27 Oct 2023 11:21:53 -0700 In-Reply-To: <20231027182217.3615211-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231027182217.3615211-1-seanjc@google.com> X-Mailer: git-send-email 2.42.0.820.g83a721a137-goog Message-ID: <20231027182217.3615211-12-seanjc@google.com> Subject: [PATCH v13 11/35] KVM: Drop .on_unlock() mmu_notifier hook From: Sean Christopherson To: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton Cc: kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , "=?UTF-8?q?Micka=C3=ABl=20Sala=C3=BCn?=" , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="UTF-8" Drop the .on_unlock() mmu_notifer hook now that it's no longer used for notifying arch code that memory has been reclaimed. Adding .on_unlock() and invoking it *after* dropping mmu_lock was a terrible idea, as doing so resulted in .on_lock() and .on_unlock() having divergent and asymmetric behavior, and set future developers up for failure, i.e. all but asked for bugs where KVM relied on using .on_unlock() to try to run a callback while holding mmu_lock. Opportunistically add a lockdep assertion in kvm_mmu_invalidate_end() to guard against future bugs of this nature. Reported-by: Isaku Yamahata Link: https://lore.kernel.org/all/20230802203119.GB2021422@ls.amr.corp.intel.com Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 13 +++---------- 1 file changed, 3 insertions(+), 10 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 2bc04c8ae1f4..cb9376833c18 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -544,7 +544,6 @@ static inline struct kvm *mmu_notifier_to_kvm(struct mmu_notifier *mn) typedef bool (*gfn_handler_t)(struct kvm *kvm, struct kvm_gfn_range *range); typedef void (*on_lock_fn_t)(struct kvm *kvm); -typedef void (*on_unlock_fn_t)(struct kvm *kvm); struct kvm_mmu_notifier_range { /* @@ -556,7 +555,6 @@ struct kvm_mmu_notifier_range { union kvm_mmu_notifier_arg arg; gfn_handler_t handler; on_lock_fn_t on_lock; - on_unlock_fn_t on_unlock; bool flush_on_ret; bool may_block; }; @@ -663,11 +661,8 @@ static __always_inline kvm_mn_ret_t __kvm_handle_hva_range(struct kvm *kvm, if (range->flush_on_ret && r.ret) kvm_flush_remote_tlbs(kvm); - if (r.found_memslot) { + if (r.found_memslot) KVM_MMU_UNLOCK(kvm); - if (!IS_KVM_NULL_FN(range->on_unlock)) - range->on_unlock(kvm); - } srcu_read_unlock(&kvm->srcu, idx); @@ -687,7 +682,6 @@ static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn, .arg = arg, .handler = handler, .on_lock = (void *)kvm_null_fn, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = true, .may_block = false, }; @@ -706,7 +700,6 @@ static __always_inline int kvm_handle_hva_range_no_flush(struct mmu_notifier *mn .end = end, .handler = handler, .on_lock = (void *)kvm_null_fn, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = false, }; @@ -813,7 +806,6 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, .end = range->end, .handler = kvm_mmu_unmap_gfn_range, .on_lock = kvm_mmu_invalidate_begin, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = true, .may_block = mmu_notifier_range_blockable(range), }; @@ -858,6 +850,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn, void kvm_mmu_invalidate_end(struct kvm *kvm) { + lockdep_assert_held_write(&kvm->mmu_lock); + /* * This sequence increase will notify the kvm page fault that * the page that is going to be mapped in the spte could have @@ -889,7 +883,6 @@ static void kvm_mmu_notifier_invalidate_range_end(struct mmu_notifier *mn, .end = range->end, .handler = (void *)kvm_null_fn, .on_lock = kvm_mmu_invalidate_end, - .on_unlock = (void *)kvm_null_fn, .flush_on_ret = false, .may_block = mmu_notifier_range_blockable(range), }; -- 2.42.0.820.g83a721a137-goog