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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DFE6AC9830B for ; Wed, 23 Sep 2026 15:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=O7DkT3TdNlYpOfcIlfLZN1+Hxti+S/5tyGjgvbR9yuI=; b=S5+PRIJAZbKZn9Qd0Y5FxA8fo6 nTBN20dtkomZeyydwW93N5CLf0SF1jmNuQlLgj8cmbCG+OcUUB5yoAkC3/X/7r5apQJnrg+DchadH +XoIF6VyY2SicKkQUrnJI4EnUZD8QGaJYgJJXyWrd6QDCn+7eBDjF93khRRmuDi20kY8fGMKaZ66a FnSDoULVczp03lUYzG20f009gtbv0zf2YnbnlPrRy8e2HlGTHEYGmHCgnScrP4dNa0VCMD7ADCNjM dXUt26NC6OpMB1+gf7Cu7LxS95ww2fRS5H1nfgFNWK+8LiueMtRjXMapqGRiadzgEh2jvrNeCMsak WkOe+K3g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9Oii-00000008gLO-2noo; Wed, 23 Sep 2026 15:17:16 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1x9Oib-00000008gHB-3JMC for linux-arm-kernel@lists.infradead.org; Wed, 23 Sep 2026 15:17:09 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 3CDD260210; Wed, 23 Sep 2026 15:17:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 622E51F00893; Wed, 23 Sep 2026 15:16:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790176628; bh=O7DkT3TdNlYpOfcIlfLZN1+Hxti+S/5tyGjgvbR9yuI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=kit6ohZ7PI8mOuQZZV6g+wXFRJYU1FjyzoCoatj4b+McSVr/K2BiN7FksX6q/JI9r GyM9QSeiosz9jIKQDcSnCuQNZqjkmrkB3UAATrefKIqye7GoUts8XhtylBLIY2B//f HmZDm3corcyHWKo5x2rIN5NbWsK457Kr53rpAxEhs/2VjgOWRuRURkUSY1O7pbY7nt hh4NY+yro5v5xTmhQ7Hk+bLmSsSS8/h1GvZawcVbu8isEvhN24mJ01TCFKbcqs4Pec vgu1EZoOAYFo/f7Epfkhp7PhNyQjJBUPaCUnV+t7qLqqfBC2qcq8/3yxKqGKDlg0Cc lpPj/hlmfMnQw== From: "Lorenzo Stoakes (ARM)" Date: Wed, 23 Sep 2026 16:15:49 +0100 Subject: [PATCH v4 06/14] KVM: arm64: Propagate and use kvm_s2_fault_result on S2 fault MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260923-kvm-arm-prefault-v4-6-d4b0b4dfa8c3@kernel.org> References: <20260923-kvm-arm-prefault-v4-0-d4b0b4dfa8c3@kernel.org> In-Reply-To: <20260923-kvm-arm-prefault-v4-0-d4b0b4dfa8c3@kernel.org> To: Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Paolo Bonzini , Jonathan Corbet , Mark Rutland , Fuad Tabba , Randy Dunlap , Christian Borntraeger , Janosch Frank , David Hildenbrand , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Sven Schnelle , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Shuah Khan , Shuah Khan Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, Jack Thomson , Jack Thomson , Alexandru Elisei , Vincent Donnefort , "Aneesh Kumar K.V" , Sean Christopherson , Claudio Imbrenda , Leo Soares Passos , Wei-Lin Chang , linux-s390@vger.kernel.org, "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=4957; i=ljs@kernel.org; h=from:subject:message-id; bh=d2RtnpecLVAubBY7OqtG18bcfCdBXcTO5lSZ4rwDIMo=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLI2v9VdqXd4ocH7mN/ia9OuXZ+X1NPuvNj5X9WneRFJC 4VrTzDpdJSyMIhxMciKKbI8/yK+P0gkbF7nBX83mDmsTCBDGLg4BWAi8ckMf/jFr2ycF99Zflv5 qpHc/BXv5M4U3Wp5bPVH4XjFievWjt8ZGbqCly5OkH/9WKNf3u4VV1VT+Zfm8o2nsqsCb237KFt RyAsA X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org When stage 2 page tables fault the net result may either be that a page is mapped, an error occurred or the fault should be retried (-EAGAIN). When a fault succeeds it may be upgraded to a PMD size via transparent_hugepage_adjust(). In order to support KVM pre-faulting the outcome of the fault and the mapping size must be recorded. Track the mapping size via new kvm_s2_fault_result struct, which is threaded through gmem_abort(), user_mem_abort() and kvm_s2_fault_map(). PKVM and SEA aren't relevant to synthetic pre-faulting so neither kvm_inject_sea() nor pkvm_mem_abort() are altered. Actual hardware faulting doesn't require this information, so kvm_handle_guest_abort() simply passes NULL kvm_s2_fault_result to gmem_abort() and user_mem_abort(). A non-NULL result also tells the abort handlers that the caller is pre-faulting rather than a vcpu, in which case -EAGAIN is propagated to the caller to allow the pre-fault to be retried. Likewise, only prepare a KVM_EXIT_MEMORY_FAULT in gmem_abort() when a real fault is being handled, as this updates vcpu state. No functional change intended. Suggested-by: Vincent Donnefort Reviewed-by: Oliver Upton Signed-off-by: Lorenzo Stoakes (ARM) --- arch/arm64/kvm/mmu.c | 43 +++++++++++++++++++++++++++++++------------ 1 file changed, 31 insertions(+), 12 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 9d799f7c1e62..ee2a4f0faa14 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1659,6 +1659,10 @@ struct kvm_s2_fault_desc { struct kvm_s2_mmu *mmu; }; +struct kvm_s2_fault_result { + unsigned long mapping_size; +}; + static bool kvm_s2_fault_is_perm(const struct kvm_s2_fault_desc *s2fd) { return esr_fsc_is_permission_fault(s2fd->esr); @@ -1684,7 +1688,8 @@ static u64 kvm_s2_perm_fault_granule(const struct kvm_s2_fault_desc *s2fd) return BIT(ARM64_HW_PGTABLE_LEVEL_SHIFT(level)); } -static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) +static int gmem_abort(const struct kvm_s2_fault_desc *s2fd, + struct kvm_s2_fault_result *result) { bool write_fault, exec_fault; bool perm_fault = kvm_s2_fault_is_perm(s2fd); @@ -1728,8 +1733,10 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) ret = kvm_gmem_get_pfn(kvm, s2fd->memslot, gfn, &pfn, &page, NULL); if (ret) { - kvm_prepare_memory_fault_exit(s2fd->vcpu, s2fd->fault_ipa, PAGE_SIZE, - write_fault, exec_fault, false); + /* If result is non-NULL this is a synthetic fault. */ + if (!result) + kvm_prepare_memory_fault_exit(s2fd->vcpu, s2fd->fault_ipa, PAGE_SIZE, + write_fault, exec_fault, false); kfree(mapping); return ret; } @@ -1784,7 +1791,13 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) if ((prot & KVM_PGTABLE_PROT_W) && !ret) mark_page_dirty_in_slot(kvm, s2fd->memslot, gfn); - return ret != -EAGAIN ? ret : 0; + if (ret == -EAGAIN) + return result ? ret : 0; + + if (result && !ret) + result->mapping_size = PAGE_SIZE; + + return ret; } struct kvm_s2_fault_vma_info { @@ -2108,7 +2121,8 @@ static int kvm_s2_fault_compute_prot(const struct kvm_s2_fault_desc *s2fd, static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, const struct kvm_s2_fault_vma_info *s2vi, enum kvm_pgtable_prot prot, - void *memcache) + void *memcache, + struct kvm_s2_fault_result *result) { enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_SHARED; struct kvm_guest_s2_mapping *mapping = NULL; @@ -2209,12 +2223,17 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, mark_page_dirty_in_slot(kvm, s2fd->memslot, gpa_to_gfn(canonical_ipa)); - if (ret != -EAGAIN) - return ret; - return 0; + if (ret == -EAGAIN) + return result ? ret : 0; + + if (result && !ret) + result->mapping_size = mapping_size; + + return ret; } -static int user_mem_abort(const struct kvm_s2_fault_desc *s2fd) +static int user_mem_abort(const struct kvm_s2_fault_desc *s2fd, + struct kvm_s2_fault_result *result) { bool perm_fault = kvm_s2_fault_is_perm(s2fd); struct kvm_s2_fault_vma_info s2vi = {}; @@ -2253,7 +2272,7 @@ static int user_mem_abort(const struct kvm_s2_fault_desc *s2fd) return ret; } - return kvm_s2_fault_map(s2fd, &s2vi, prot, memcache); + return kvm_s2_fault_map(s2fd, &s2vi, prot, memcache, result); } /* Resolve the access fault by making the page young again. */ @@ -2532,9 +2551,9 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu) !kvm_s2_fault_is_exec(&s2fd)); if (kvm_slot_has_gmem(memslot)) - ret = gmem_abort(&s2fd); + ret = gmem_abort(&s2fd, NULL); else - ret = user_mem_abort(&s2fd); + ret = user_mem_abort(&s2fd, NULL); } if (ret == 0) -- 2.55.0