From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 C750637F8C6 for ; Fri, 26 Jun 2026 23:14:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782515670; cv=none; b=Sw9K7hhVxHJHK6xdOSzznnt+c7v0fvjC6T12WT6e/884gae9CGp8KyG3v5U3lFOrcntmZQ1ww8+q0iDyJ5s4oumQN+tkGlHqiyNfP8J0GA5bbk1/smZ8KUpHKR6WMynF9CTUVsDM+SAQvpOVL7URHjpho5HmOoio94U/CJgOJRA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782515670; c=relaxed/simple; bh=M+ns7hIsjvqgw42ToErJ/i81C5vsomZl7iRsyhMGNzc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=HwS8evAafBTNBPvBP/7pyWxmoJilGTX8jlb38AJVT218eywnsvpk4dJm+Tk88UsT4ob1VHJ4Ieyyh+jAffEDiohqdCJ/ocvA9MSX8wS3wXCH+8YFmer0IImWA0hPryfT90zUvrMwhIVdl3q30tuCju1QPWxdOjJRw7PhNF3Wkt4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=vA6SgSh4; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vA6SgSh4" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-37e1f96b248so785741a91.3 for ; Fri, 26 Jun 2026 16:14:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782515666; x=1783120466; 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=CckMd+ZBZTPBjpcDx+h5yQ8CEqxWh1RxSUyuEWlO4OY=; b=vA6SgSh47OrWmPM487Qw8UnDN8s1+7eRejZamrbWNUmX0nype2flWC87jfu+o+BvSV t37CnM//xK8monNfy1SNohDCnlMO59BD16HrMbvVa1nQoGGdEepPAXTdIDt8IndSlLcO OJ5urF19LfDlRCgsVqZki6smW9xnUsJNtw8BS2krOTLRMwVfsLG2HHVRyWmQ3EPWO0xO TmF+zS4vBg7DkF1g+ne/UndLN2DGPGmtqYHCrDJmpGz+ttjkJqfKDwHMa3+JQS9j6066 A4QldNeJiUxgaEH6kQiNFWIABrEkigrHH/bPDvZZPYsuMnyI9diX6+74DPMNfmO0LMx/ s4yw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782515666; x=1783120466; 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=CckMd+ZBZTPBjpcDx+h5yQ8CEqxWh1RxSUyuEWlO4OY=; b=dEHItM8tp4EO2gCWIk07yGUqdn6jwoPCQrN+LF3cq64kKoZuhP1+0QNClTQe74GOMi Recyd4SeDzIhIPzPdZrhWZTgqcHvpf9w5grfrVgtKLwRsTbe43zykh1Jgp2ntwLsYFnx 2R4RoYTdLlnn8gJ7gxco50oDNct/oEW/S71bE2BoPEA/j+NzBQEOAhXnqCdilruqhAnL We/MktA0VmIrPYecc6fyhwQR0ovXLqxtwg2gYocvNq2dd2p7yHgz0jTsCiqEWOuuB8ju NCpAETH3OErCoPMVzWrcOIcTs+Uu8WD73V0t3NZ5YgNmvgc6zHHKp2iW7kgmGrY8wpYk zxIQ== X-Forwarded-Encrypted: i=1; AHgh+RoL46s01Yk3LkRzvLG2TUpKoEDAVFxVBVsv/fXn+NQKLBM19puV3/ShHvoLgAVmiJjf87An1+4ZugaiHTg=@vger.kernel.org X-Gm-Message-State: AOJu0YxlzgATMj8W5eMqAq9GyqL5fUXgMMpuBD1nPYiOFAD3dOFRqSst v2fLlJhNNI3YLrkf0MZrWNs3q1VXVNCtiFhybvLU9Hk/MJS3vb1fb557dW/QT+7QBnkFrqnZyHg S4zLeHg== X-Received: from pjvn5.prod.google.com ([2002:a17:90a:de85:b0:37d:ea95:4421]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:5282:b0:368:ed26:15b2 with SMTP id 98e67ed59e1d1-37dfa1b7ea8mr8569014a91.8.1782515665869; Fri, 26 Jun 2026 16:14:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 26 Jun 2026 16:14:13 -0700 In-Reply-To: <20260626231416.3943216-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260626231416.3943216-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.rc0.799.gd6f94ed593-goog Message-ID: <20260626231416.3943216-7-seanjc@google.com> Subject: [PATCH v2 6/9] KVM: x86/mmu: Split kvm_mmu_zap_all_fast() into "front" and "back" halves From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Hyunwoo Kim , Tom Lendacky , Michael Roth , "=?UTF-8?q?J=C3=B6rg=20R=C3=B6del?=" , Fuad Tabba , Ackerley Tng Content-Type: text/plain; charset="UTF-8" Split kvm_mmu_zap_all_fast() into a "front half" and a "back half", where the front half is everything that runs with mmu_lock held for write, and the back half is the code that runs outside of mmu_lock. Manually invoke the two halves when zapping in response to a memslot being DELETE or MOVED, and share the mmu_lock critical section between the "fast zap all" and "zap only the memslot" paths. This will allow putting more code inside the critical section without having to take mmu_lock twice in quick succession. No functional change intended. Cc: stable@vger.kernel.org # 6.12.x Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 48 +++++++++++++++++++++++++++++------------- 1 file changed, 33 insertions(+), 15 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 223d80b12b9b..5925db37543f 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -6921,20 +6921,11 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) kvm_mmu_commit_zap_page(kvm, &invalid_list); } -/* - * Fast invalidate all shadow pages and use lock-break technique - * to zap obsolete pages. - * - * It's required when memslot is being deleted or VM is being - * destroyed, in these cases, we should ensure that KVM MMU does - * not use any resource of the being-deleted slot or all slots - * after calling the function. - */ -static void kvm_mmu_zap_all_fast(struct kvm *kvm) +static void __kvm_mmu_zap_all_fast_front_half(struct kvm *kvm) { lockdep_assert_held(&kvm->slots_lock); + lockdep_assert_held_write(&kvm->mmu_lock); - write_lock(&kvm->mmu_lock); trace_kvm_mmu_zap_all_fast(kvm); /* @@ -6971,8 +6962,12 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); kvm_zap_obsolete_pages(kvm); +} - write_unlock(&kvm->mmu_lock); +static void __kvm_mmu_zap_all_fast_back_half(struct kvm *kvm) +{ + lockdep_assert_held(&kvm->slots_lock); + lockdep_assert_not_held(&kvm->mmu_lock); /* * Zap the invalidated TDP MMU roots, all SPTEs must be dropped before @@ -6986,6 +6981,24 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) kvm_tdp_mmu_zap_invalidated_roots(kvm, true); } +/* + * Fast invalidate all shadow pages and use lock-break technique + * to zap obsolete pages. + * + * It's required when memslot is being deleted or VM is being + * destroyed, in these cases, we should ensure that KVM MMU does + * not use any resource of the being-deleted slot or all slots + * after calling the function. + */ +static void kvm_mmu_zap_all_fast(struct kvm *kvm) +{ + write_lock(&kvm->mmu_lock); + __kvm_mmu_zap_all_fast_front_half(kvm); + write_unlock(&kvm->mmu_lock); + + __kvm_mmu_zap_all_fast_back_half(kvm); +} + int kvm_mmu_init_vm(struct kvm *kvm) { int r, i; @@ -7578,14 +7591,19 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm, }; bool flush; + write_lock(&kvm->mmu_lock); + if (kvm_memslot_flush_zap_all(kvm)) { - kvm_mmu_zap_all_fast(kvm); + __kvm_mmu_zap_all_fast_front_half(kvm); } else { - write_lock(&kvm->mmu_lock); flush = kvm_unmap_gfn_range(kvm, &range); kvm_mmu_zap_memslot_pages_and_flush(kvm, slot, flush); - write_unlock(&kvm->mmu_lock); } + + write_unlock(&kvm->mmu_lock); + + if (kvm_memslot_flush_zap_all(kvm)) + __kvm_mmu_zap_all_fast_back_half(kvm); } void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) -- 2.55.0.rc0.799.gd6f94ed593-goog