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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BD8D5C6FD1D for ; Fri, 17 Mar 2023 18:27:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230125AbjCQS1V (ORCPT ); Fri, 17 Mar 2023 14:27:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35200 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230080AbjCQS1T (ORCPT ); Fri, 17 Mar 2023 14:27:19 -0400 Received: from out-20.mta0.migadu.com (out-20.mta0.migadu.com [IPv6:2001:41d0:1004:224b::14]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BCA5B311E2 for ; Fri, 17 Mar 2023 11:27:14 -0700 (PDT) Date: Fri, 17 Mar 2023 18:27:10 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1679077633; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=4oKF9l25tYdyvWLnXrBZe3srNKkedksE/M0x/BYjlLw=; b=ngjU+Uzunf8+sUBFoB1rW4gjXEc7yaAOxJ4JpVjR2EMHmSnRtMhev8TN0AoC07lpYURv9/ 1PU0FCnoQNu+V1TOlVklWjzBYUuvApNcazbHMyl3K2Bvy+Cb5aKAdaTPO89ddQfV2Dv5yt 7EQA+ewGFcRZfGfVeXQU8zyWsW1zQ4s= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Oliver Upton To: Anish Moorthy Cc: seanjc@google.com, jthoughton@google.com, kvm@vger.kernel.org Subject: Re: [WIP Patch v2 12/14] KVM: arm64: Implement KVM_CAP_MEMORY_FAULT_NOWAIT Message-ID: References: <20230315021738.1151386-1-amoorthy@google.com> <20230315021738.1151386-13-amoorthy@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230315021738.1151386-13-amoorthy@google.com> X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, Mar 15, 2023 at 02:17:36AM +0000, Anish Moorthy wrote: > When a memslot has the KVM_MEM_MEMORY_FAULT_EXIT flag set, exit to > userspace upon encountering a page fault for which the userspace > page tables do not contain a present mapping. > > Signed-off-by: Anish Moorthy > Acked-by: James Houghton > --- > arch/arm64/kvm/arm.c | 1 + > arch/arm64/kvm/mmu.c | 14 ++++++++++++-- > 2 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > index 3bd732eaf0872..f8337e757c777 100644 > --- a/arch/arm64/kvm/arm.c > +++ b/arch/arm64/kvm/arm.c > @@ -220,6 +220,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) > case KVM_CAP_VCPU_ATTRIBUTES: > case KVM_CAP_PTP_KVM: > case KVM_CAP_ARM_SYSTEM_SUSPEND: > + case KVM_CAP_MEMORY_FAULT_NOWAIT: > r = 1; > break; > case KVM_CAP_SET_GUEST_DEBUG2: > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 735044859eb25..0d04ffc81f783 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -1206,6 +1206,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > unsigned long vma_pagesize, fault_granule; > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; > struct kvm_pgtable *pgt; > + bool exit_on_memory_fault = kvm_slot_fault_on_absent_mapping(memslot); > > fault_granule = 1UL << ARM64_HW_PGTABLE_LEVEL_SHIFT(fault_level); > write_fault = kvm_is_write_fault(vcpu); > @@ -1303,8 +1304,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, > */ > smp_rmb(); > > - pfn = __gfn_to_pfn_memslot(memslot, gfn, false, false, NULL, > - write_fault, &writable, NULL); > + pfn = __gfn_to_pfn_memslot( > + memslot, gfn, exit_on_memory_fault, false, NULL, > + write_fault, &writable, NULL); As stated before [*], this google3-esque style does not match the kernel style guide. You may want to check if your work machine is setting up a G3-specific editor configuration behind your back. [*] https://lore.kernel.org/kvm/Y+0QRsZ4yWyUdpnc@google.com/ > + if (exit_on_memory_fault && pfn == KVM_PFN_ERR_FAULT) { nit: I don't think the local is explicitly necessary. I still find this readable: if (pfn == KVM_PFN_ERR_FAULT && kvm_slot_fault_on_absent_mapping(memslot)) > + vcpu->run->exit_reason = KVM_EXIT_MEMORY_FAULT; > + vcpu->run->memory_fault.flags = 0; > + vcpu->run->memory_fault.gpa = gfn << PAGE_SHIFT; > + vcpu->run->memory_fault.len = vma_pagesize; > + return 0; > + } > if (pfn == KVM_PFN_ERR_HWPOISON) { > kvm_send_hwpoison_signal(hva, vma_shift); > return 1; > -- > 2.40.0.rc1.284.g88254d51c5-goog > > -- Thanks, Oliver