From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 4045D46AA79; Mon, 14 Sep 2026 12:27:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789388828; cv=none; b=XlLKcIvbQfn8bzo+DDG2CpbgKgISBODjpBv23udAgM7q1/pCwCkFovzbWAPhpBnSblRM3DPyfxXylyBAWlVCwfVEv7zQmDrGAlnEQqEDdNJV2XpQyignbTk0xpgFbxT8NLVs2sxMhJU7FVdklACjPx3Cj8lU8PYhNr0RMG3PPG8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789388828; c=relaxed/simple; bh=7h5BNF2TyNFGKTZFDAT77YrYi9+yuhGSKydMX9EZVMo=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=LyAj+X7rcwuSoT6Sld/Q9opJq+RI6Qosgz6RIvuRkRk2qTj33L/VXWP58EsGfgUmuMKiJ2rdudN58ezXX3ivg3u+rsKK3obyjqMW1rNDY0SzQAe7WZfqGWoJfaphBYAx7+latOeOmh3UZsgHN2uydDFi4vWPeggqjO522x0PMmI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Y0IwcxuX; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Y0IwcxuX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 667981F00893; Mon, 14 Sep 2026 12:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789388825; bh=kfg0Uz8+KztBDtg3H0+qNEem9pKDqqYVBa07KrFCXCA=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=Y0IwcxuX0w/WvGSBZT3ojW/ME7dow3oCVDawD0flWeh6jWWkI8QWODZUzZMmjwe/B 4VU4fHsHZc0zyXnmq868pX14HRYBiITiw8MW2ugWOITzNFdGYpjogtppY0ixIguo5U 3YNMESJ4llRoHzSJt6IwGjLIZTj81ZUdHosnMZavRsiYirgqHHmrnbdbZpBTbE+t0e cDfpNXMTZ8DEbCe2uA3r9EEIrXHVeNA3yurCq4oQqpnXcaI6fGuvvuPm7zcntOJkIr TXCADD8sujBUmxChcp5FBfa/WxOYkxnkVduYpNseGiDJqvEcxHPOaPa8AaMP9t2wlZ sWDZuCq9S6lyw== From: "Lorenzo Stoakes (ARM)" Date: Mon, 14 Sep 2026 13:26:16 +0100 Subject: [PATCH v2 05/13] KVM: arm64: Propagate and use kvm_s2_fault_result on S2 fault Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260914-kvm-arm-prefault-v2-5-26fb47f74b73@kernel.org> References: <20260914-kvm-arm-prefault-v2-0-26fb47f74b73@kernel.org> In-Reply-To: <20260914-kvm-arm-prefault-v2-0-26fb47f74b73@kernel.org> To: Catalin Marinas , Will Deacon , Marc Zyngier , Oliver Upton , Fuad Tabba , Joey Gouly , Steffen Eiden , Suzuki K Poulose , Zenghui Yu , Paolo Bonzini , Jonathan Corbet 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 , "Lorenzo Stoakes (ARM)" X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=openpgp-sha256; l=4228; i=ljs@kernel.org; h=from:subject:message-id; bh=7h5BNF2TyNFGKTZFDAT77YrYi9+yuhGSKydMX9EZVMo=; b=owGbwMvMwCV2fu7ZrsZH9SKMp9WSGLKWP/86OaVhwydvpoC2R3t2vPXcX80gaHMmc16puUTH3 fajd+1aO0pZGMS4GGTFFFmefxHfHyQSNq/zgr8bzBxWJpAhDFycAjAR192MDCsEvqkdEtT7Ncsi 0/fLOS+2ZEn/RaI7PWu62SaouqzvSGdkeNvM3+i0/vYDa6aQpUe5rqfc/O9u8jXcMyxswwJeZwN hTgA= X-Developer-Key: i=ljs@kernel.org; a=openpgp; fpr=E7F417BF5214569E89D04F46CF9DCD8A81E27F14 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. No functional change intended. Suggested-by: Vincent Donnefort Signed-off-by: Lorenzo Stoakes (ARM) --- arch/arm64/kvm/mmu.c | 37 +++++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index f402481e8a4e..13541218cadb 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1607,6 +1607,10 @@ 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); @@ -1632,7 +1636,8 @@ 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); @@ -1714,7 +1719,13 @@ 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 { @@ -2038,7 +2049,8 @@ 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; bool writable = prot & KVM_PGTABLE_PROT_W; @@ -2117,12 +2129,17 @@ static int kvm_s2_fault_map(const struct kvm_s2_fault_desc *s2fd, mark_page_dirty_in_slot(kvm, s2fd->memslot, gpa_to_gfn(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 = {}; @@ -2161,7 +2178,7 @@ 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. */ @@ -2440,9 +2457,9 @@ 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