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[99.241.198.116]) by smtp.gmail.com with ESMTPSA id g7-20020a0566380c4700b00339d892cc89sm1510446jal.83.2022.06.22.14.37.01 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 22 Jun 2022 14:37:02 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterx@redhat.com, Paolo Bonzini , Andrew Morton , David Hildenbrand , "Dr . David Alan Gilbert" , Andrea Arcangeli , Linux MM Mailing List , Sean Christopherson Subject: [PATCH 1/4] mm/gup: Add FOLL_INTERRUPTIBLE Date: Wed, 22 Jun 2022 17:36:53 -0400 Message-Id: <20220622213656.81546-2-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220622213656.81546-1-peterx@redhat.com> References: <20220622213656.81546-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" We have had FAULT_FLAG_INTERRUPTIBLE but it was never applied to GUPs. One issue with it is that not all GUP paths are able to handle signal delivers besides SIGKILL. That's not ideal for the GUP users who are actually able to handle these cases, like KVM. KVM uses GUP extensively on faulting guest pages, during which we've got existing infrastructures to retry a page fault at a later time. Allowing the GUP to be interrupted by generic signals can make KVM related threads to be more responsive. For examples: (1) SIGUSR1: which QEMU/KVM uses to deliver an inter-process IPI, e.g. when the admin issues a vm_stop QMP command, SIGUSR1 can be generated to kick the vcpus out of kernel context immediately, (2) SIGINT: which can be used with interactive hypervisor users to stop a virtual machine with Ctrl-C without any delays/hangs, (3) SIGTRAP: which grants GDB capability even during page faults that are stuck for a long time. Normally hypervisor will be able to receive these signals properly, but not if we're stuck in a GUP for a long time for whatever reason. It happens easily with a stucked postcopy migration when e.g. a network temp failure happens, then some vcpu threads can hang death waiting for the pages. With the new FOLL_INTERRUPTIBLE, we can allow GUP users like KVM to selectively enable the ability to trap these signals. Signed-off-by: Peter Xu Reviewed-by: John Hubbard --- include/linux/mm.h | 1 + mm/gup.c | 33 +++++++++++++++++++++++++++++---- 2 files changed, 30 insertions(+), 4 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index bc8f326be0ce..ebdf8a6b86c1 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2941,6 +2941,7 @@ struct page *follow_page(struct vm_area_struct *vma, = unsigned long address, #define FOLL_SPLIT_PMD 0x20000 /* split huge pmd before returning */ #define FOLL_PIN 0x40000 /* pages must be released via unpin_user_page */ #define FOLL_FAST_ONLY 0x80000 /* gup_fast: prevent fall-back to slow gup = */ +#define FOLL_INTERRUPTIBLE 0x100000 /* allow interrupts from generic sign= als */ =20 /* * FOLL_PIN and FOLL_LONGTERM may be used in various combinations with each diff --git a/mm/gup.c b/mm/gup.c index 551264407624..ad74b137d363 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -933,8 +933,17 @@ static int faultin_page(struct vm_area_struct *vma, fault_flags |=3D FAULT_FLAG_WRITE; if (*flags & FOLL_REMOTE) fault_flags |=3D FAULT_FLAG_REMOTE; - if (locked) + if (locked) { fault_flags |=3D FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; + /* + * We should only grant FAULT_FLAG_INTERRUPTIBLE when we're + * (at least) killable. It also mostly means we're not + * with NOWAIT. Otherwise ignore FOLL_INTERRUPTIBLE since + * it won't make a lot of sense to be used alone. + */ + if (*flags & FOLL_INTERRUPTIBLE) + fault_flags |=3D FAULT_FLAG_INTERRUPTIBLE; + } if (*flags & FOLL_NOWAIT) fault_flags |=3D FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT; if (*flags & FOLL_TRIED) { @@ -1322,6 +1331,22 @@ int fixup_user_fault(struct mm_struct *mm, } EXPORT_SYMBOL_GPL(fixup_user_fault); =20 +/* + * GUP always responds to fatal signals. When FOLL_INTERRUPTIBLE is + * specified, it'll also respond to generic signals. The caller of GUP + * that has FOLL_INTERRUPTIBLE should take care of the GUP interruption. + */ +static bool gup_signal_pending(unsigned int flags) +{ + if (fatal_signal_pending(current)) + return true; + + if (!(flags & FOLL_INTERRUPTIBLE)) + return false; + + return signal_pending(current); +} + /* * Please note that this function, unlike __get_user_pages will not * return 0 for nr_pages > 0 without FOLL_NOWAIT @@ -1403,11 +1428,11 @@ static __always_inline long __get_user_pages_locked= (struct mm_struct *mm, * Repeat on the address that fired VM_FAULT_RETRY * with both FAULT_FLAG_ALLOW_RETRY and * FAULT_FLAG_TRIED. Note that GUP can be interrupted - * by fatal signals, so we need to check it before we + * by fatal signals of even common signals, depending on + * the caller's request. So we need to check it before we * start trying again otherwise it can loop forever. */ - - if (fatal_signal_pending(current)) { + if (gup_signal_pending(flags)) { if (!pages_done) pages_done =3D -EINTR; break; --=20 2.32.0 From nobody Mon Apr 20 02:56:14 2026 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 982A3C43334 for ; Wed, 22 Jun 2022 21:37:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234846AbiFVVhS (ORCPT ); Wed, 22 Jun 2022 17:37:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58538 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233713AbiFVVhK (ORCPT ); Wed, 22 Jun 2022 17:37:10 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 0583D35DC6 for ; Wed, 22 Jun 2022 14:37:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655933829; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vhppIX6vNX1hZt/miaFbnfjIfVwbxcf3RlezEUIw2Gs=; b=ZDzQ2sBMUQMfUtFaRLJeh0c30nPsyFVDXGPEb/MCV3o9np/HUgOOqRR/gkl74ouWif6ptg uFIrO3bKf/iagzVsdp610nRnptrvvxjhCW5aTKqLC21pFU/Ek6pT59vHjl8kOyix2kQFNP Eup820d+VXITRjj2XVtJxj6yVVa6lW8= Received: from mail-il1-f197.google.com (mail-il1-f197.google.com [209.85.166.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-313-i_A0LEsEMuOnvvYrYS-I5Q-1; Wed, 22 Jun 2022 17:37:07 -0400 X-MC-Unique: i_A0LEsEMuOnvvYrYS-I5Q-1 Received: by mail-il1-f197.google.com with SMTP id n14-20020a056e021bae00b002d92c91da8aso3628918ili.15 for ; Wed, 22 Jun 2022 14:37:07 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=vhppIX6vNX1hZt/miaFbnfjIfVwbxcf3RlezEUIw2Gs=; b=P+wDHo+4cURqwROiFngbWdja3jLLyiXacBhwZy+NLO0SgeaB7P6RNc3k9STJuHHTYG myv+E97pXH4r3v3TQo2leFR45LkFEB4gz4qCTK0ubT32Y5UYS4Y2vwnHEaTgOylgCg2g 4Wx6wCsIm15/A2LlqKHDIc3nRbBJkezzvTnCyL6JvnIv2MXdMxn9OzRMAMV0l6kQKr5K NteGG6ztI/hpbcjdMO34IEHt0RCIOoW9fnZBNL1FT/s+LRx+jZmGc6OQrGHfM0V0XGZQ rUc/FWyf+uLxES/j0snQePZ7dCAz50F54FZFn1Qv7K0r+2HtRF5r3xFcv8cA+sbvl2Nn JSVA== X-Gm-Message-State: AJIora8g/VLMbBRMUJmtalDL+2Z2BXIYHg/7vwcTDpOJYJmH8Yydolh4 GOW8uqxg/WhA4v/17Zqk4eTLXnA3OeprdghKvBIlaP2SzE+KFIEkSHc9OeubyjEcFs51W/Aut6F gCedCV+FWF7MR1T/XlyxoiD1w X-Received: by 2002:a05:6e02:1a28:b0:2d8:e770:d43f with SMTP id g8-20020a056e021a2800b002d8e770d43fmr3278551ile.137.1655933826043; Wed, 22 Jun 2022 14:37:06 -0700 (PDT) X-Google-Smtp-Source: AGRyM1uJcMRkwsDNKTMq4mKtUplbgjsXpC8ptulSt8S8Q5/HCNbhHNMkLxzTCVOW888ONQuKUYm7dA== X-Received: by 2002:a05:6e02:1a28:b0:2d8:e770:d43f with SMTP id g8-20020a056e021a2800b002d8e770d43fmr3278518ile.137.1655933825523; Wed, 22 Jun 2022 14:37:05 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id g7-20020a0566380c4700b00339d892cc89sm1510446jal.83.2022.06.22.14.37.03 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 22 Jun 2022 14:37:04 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterx@redhat.com, Paolo Bonzini , Andrew Morton , David Hildenbrand , "Dr . David Alan Gilbert" , Andrea Arcangeli , Linux MM Mailing List , Sean Christopherson Subject: [PATCH 2/4] kvm: Merge "atomic" and "write" in __gfn_to_pfn_memslot() Date: Wed, 22 Jun 2022 17:36:54 -0400 Message-Id: <20220622213656.81546-3-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220622213656.81546-1-peterx@redhat.com> References: <20220622213656.81546-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Merge two boolean parameters into a bitmask flag called kvm_gtp_flag_t for __gfn_to_pfn_memslot(). This cleans the parameter lists, and also prepare for new boolean to be added to __gfn_to_pfn_memslot(). Signed-off-by: Peter Xu --- arch/arm64/kvm/mmu.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_radix.c | 5 ++-- arch/x86/kvm/mmu/mmu.c | 10 +++---- include/linux/kvm_host.h | 9 ++++++- virt/kvm/kvm_main.c | 37 +++++++++++++++----------- virt/kvm/kvm_mm.h | 6 +++-- virt/kvm/pfncache.c | 2 +- 8 files changed, 49 insertions(+), 30 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index f5651a05b6a8..ce1edb512b4e 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -1204,8 +1204,9 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys= _addr_t fault_ipa, */ smp_rmb(); =20 - pfn =3D __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - write_fault, &writable, NULL); + pfn =3D __gfn_to_pfn_memslot(memslot, gfn, + write_fault ? KVM_GTP_WRITE : 0, + NULL, &writable, NULL); if (pfn =3D=3D KVM_PFN_ERR_HWPOISON) { kvm_send_hwpoison_signal(hva, vma_shift); return 0; diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_= 64_mmu_hv.c index 514fd45c1994..e2769d58dd87 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -598,8 +598,9 @@ int kvmppc_book3s_hv_page_fault(struct kvm_vcpu *vcpu, write_ok =3D true; } else { /* Call KVM generic code to do the slow-path check */ - pfn =3D __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - writing, &write_ok, NULL); + pfn =3D __gfn_to_pfn_memslot(memslot, gfn, + writing ? KVM_GTP_WRITE : 0, + NULL, &write_ok, NULL); if (is_error_noslot_pfn(pfn)) return -EFAULT; page =3D NULL; diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book= 3s_64_mmu_radix.c index 42851c32ff3b..232b17c75b83 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -845,8 +845,9 @@ int kvmppc_book3s_instantiate_page(struct kvm_vcpu *vcp= u, unsigned long pfn; =20 /* Call KVM generic code to do the slow-path check */ - pfn =3D __gfn_to_pfn_memslot(memslot, gfn, false, NULL, - writing, upgrade_p, NULL); + pfn =3D __gfn_to_pfn_memslot(memslot, gfn, + writing ? KVM_GTP_WRITE : 0, + NULL, upgrade_p, NULL); if (is_error_noslot_pfn(pfn)) return -EFAULT; page =3D NULL; diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index f4653688fa6d..e92f1ab63d6a 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3968,6 +3968,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,= struct kvm_async_pf *work) =20 static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *f= ault) { + kvm_gtp_flag_t flags =3D fault->write ? KVM_GTP_WRITE : 0; struct kvm_memory_slot *slot =3D fault->slot; bool async; =20 @@ -3999,8 +4000,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, str= uct kvm_page_fault *fault) } =20 async =3D false; - fault->pfn =3D __gfn_to_pfn_memslot(slot, fault->gfn, false, &async, - fault->write, &fault->map_writable, + fault->pfn =3D __gfn_to_pfn_memslot(slot, fault->gfn, flags, + &async, &fault->map_writable, &fault->hva); if (!async) return RET_PF_CONTINUE; /* *pfn has correct page already */ @@ -4016,9 +4017,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, str= uct kvm_page_fault *fault) } } =20 - fault->pfn =3D __gfn_to_pfn_memslot(slot, fault->gfn, false, NULL, - fault->write, &fault->map_writable, - &fault->hva); + fault->pfn =3D __gfn_to_pfn_memslot(slot, fault->gfn, flags, NULL, + &fault->map_writable, &fault->hva); return RET_PF_CONTINUE; } =20 diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index c20f2d55840c..b646b6fcaec6 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1146,8 +1146,15 @@ kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn= , bool write_fault, bool *writable); kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn= ); kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gf= n_t gfn); + +/* gfn_to_pfn (gtp) flags */ +typedef unsigned int __bitwise kvm_gtp_flag_t; + +#define KVM_GTP_WRITE ((__force kvm_gtp_flag_t) BIT(0)) +#define KVM_GTP_ATOMIC ((__force kvm_gtp_flag_t) BIT(1)) + kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t g= fn, - bool atomic, bool *async, bool write_fault, + kvm_gtp_flag_t gtp_flags, bool *async, bool *writable, hva_t *hva); =20 void kvm_release_pfn_clean(kvm_pfn_t pfn); diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 64ec2222a196..952400b42ee9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2444,9 +2444,11 @@ static bool hva_to_pfn_fast(unsigned long addr, bool= write_fault, * The slow path to get the pfn of the specified host virtual address, * 1 indicates success, -errno is returned if error is detected. */ -static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fau= lt, +static int hva_to_pfn_slow(unsigned long addr, bool *async, + kvm_gtp_flag_t gtp_flags, bool *writable, kvm_pfn_t *pfn) { + bool write_fault =3D gtp_flags & KVM_GTP_WRITE; unsigned int flags =3D FOLL_HWPOISON; struct page *page; int npages =3D 0; @@ -2565,20 +2567,22 @@ static int hva_to_pfn_remapped(struct vm_area_struc= t *vma, /* * Pin guest page in memory and return its pfn. * @addr: host virtual address which maps memory to the guest - * @atomic: whether this function can sleep + * @gtp_flags: kvm_gtp_flag_t flags (atomic, write, ..) * @async: whether this function need to wait IO complete if the * host page is not in the memory - * @write_fault: whether we should get a writable host page * @writable: whether it allows to map a writable host page for !@write_fa= ult * - * The function will map a writable host page for these two cases: + * The function will map a writable (KVM_GTP_WRITE set) host page for these + * two cases: * 1): @write_fault =3D true * 2): @write_fault =3D false && @writable, @writable will tell the caller * whether the mapping is writable. */ -kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, - bool write_fault, bool *writable) +kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *a= sync, + bool *writable) { + bool write_fault =3D gtp_flags & KVM_GTP_WRITE; + bool atomic =3D gtp_flags & KVM_GTP_ATOMIC; struct vm_area_struct *vma; kvm_pfn_t pfn =3D 0; int npages, r; @@ -2592,7 +2596,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic,= bool *async, if (atomic) return KVM_PFN_ERR_FAULT; =20 - npages =3D hva_to_pfn_slow(addr, async, write_fault, writable, &pfn); + npages =3D hva_to_pfn_slow(addr, async, gtp_flags, writable, &pfn); if (npages =3D=3D 1) return pfn; =20 @@ -2625,10 +2629,11 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomi= c, bool *async, } =20 kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t g= fn, - bool atomic, bool *async, bool write_fault, + kvm_gtp_flag_t gtp_flags, bool *async, bool *writable, hva_t *hva) { - unsigned long addr =3D __gfn_to_hva_many(slot, gfn, NULL, write_fault); + unsigned long addr =3D __gfn_to_hva_many(slot, gfn, NULL, + gtp_flags & KVM_GTP_WRITE); =20 if (hva) *hva =3D addr; @@ -2651,28 +2656,30 @@ kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_mem= ory_slot *slot, gfn_t gfn, writable =3D NULL; } =20 - return hva_to_pfn(addr, atomic, async, write_fault, - writable); + return hva_to_pfn(addr, gtp_flags, async, writable); } EXPORT_SYMBOL_GPL(__gfn_to_pfn_memslot); =20 kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault, bool *writable) { - return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, false, NULL, - write_fault, writable, NULL); + return __gfn_to_pfn_memslot(gfn_to_memslot(kvm, gfn), gfn, + write_fault ? KVM_GTP_WRITE : 0, + NULL, writable, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_prot); =20 kvm_pfn_t gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t gfn) { - return __gfn_to_pfn_memslot(slot, gfn, false, NULL, true, NULL, NULL); + return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE, + NULL, NULL, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot); =20 kvm_pfn_t gfn_to_pfn_memslot_atomic(const struct kvm_memory_slot *slot, gf= n_t gfn) { - return __gfn_to_pfn_memslot(slot, gfn, true, NULL, true, NULL, NULL); + return __gfn_to_pfn_memslot(slot, gfn, KVM_GTP_WRITE | KVM_GTP_ATOMIC, + NULL, NULL, NULL); } EXPORT_SYMBOL_GPL(gfn_to_pfn_memslot_atomic); =20 diff --git a/virt/kvm/kvm_mm.h b/virt/kvm/kvm_mm.h index 41da467d99c9..1c870911eb48 100644 --- a/virt/kvm/kvm_mm.h +++ b/virt/kvm/kvm_mm.h @@ -3,6 +3,8 @@ #ifndef __KVM_MM_H__ #define __KVM_MM_H__ 1 =20 +#include + /* * Architectures can choose whether to use an rwlock or spinlock * for the mmu_lock. These macros, for use in common code @@ -24,8 +26,8 @@ #define KVM_MMU_READ_UNLOCK(kvm) spin_unlock(&(kvm)->mmu_lock) #endif /* KVM_HAVE_MMU_RWLOCK */ =20 -kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async, - bool write_fault, bool *writable); +kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag_t gtp_flags, bool *a= sync, + bool *writable); =20 #ifdef CONFIG_HAVE_KVM_PFNCACHE void gfn_to_pfn_cache_invalidate_start(struct kvm *kvm, diff --git a/virt/kvm/pfncache.c b/virt/kvm/pfncache.c index dd84676615f1..0f9f6b5d2fbb 100644 --- a/virt/kvm/pfncache.c +++ b/virt/kvm/pfncache.c @@ -123,7 +123,7 @@ static kvm_pfn_t hva_to_pfn_retry(struct kvm *kvm, unsi= gned long uhva) smp_rmb(); =20 /* We always request a writeable mapping */ - new_pfn =3D hva_to_pfn(uhva, false, NULL, true, NULL); + new_pfn =3D hva_to_pfn(uhva, KVM_GTP_WRITE, NULL, NULL); if (is_error_noslot_pfn(new_pfn)) break; =20 --=20 2.32.0 From nobody Mon Apr 20 02:56:14 2026 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 9CD54CCA479 for ; Wed, 22 Jun 2022 21:37:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236566AbiFVVhV (ORCPT ); Wed, 22 Jun 2022 17:37:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58570 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234232AbiFVVhM (ORCPT ); Wed, 22 Jun 2022 17:37:12 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id A476935DD2 for ; Wed, 22 Jun 2022 14:37:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655933830; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ghHac7UV1N6vPGfjk7ojRXZFbMUyEtSeJQo5S/wAoOg=; b=YRCpHorWcD1kefTMslBVEa8A/M7umsaxfZ5hCP746xr4zzujlNPUdvl1xdbwO8Zzy8f9x6 i6mwrOuYAgsHnUCrQhy+VWbOYJnSFriO+vba/tR/zSnYCQTNSJAsQh59G562sRWnfANjCH /vwigs6EeOy3kx+XDLclBKFWkpJsnx0= Received: from mail-io1-f70.google.com (mail-io1-f70.google.com [209.85.166.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-144-a6x3Oaf1PSWCcNRITVpL1Q-1; Wed, 22 Jun 2022 17:37:09 -0400 X-MC-Unique: a6x3Oaf1PSWCcNRITVpL1Q-1 Received: by mail-io1-f70.google.com with SMTP id n20-20020a6b7214000000b00669cae33d00so9835558ioc.17 for ; Wed, 22 Jun 2022 14:37:09 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=ghHac7UV1N6vPGfjk7ojRXZFbMUyEtSeJQo5S/wAoOg=; b=KNqzNFDvpaiucvWICGOt/oPWoUeJWcUKXDC1N+1wVfLyTvRLPR9M/A0FuYps4xF3Bh YTQrMig/MpWVbY5iGWntRhq9RyRGub7kCXVtjfNYJ/qAuPG5ekLc1wCb9HVLcwHYWGef nLkkDewsLy1nMJWtz+cSb1bRcE5kQbgvO8PlHqjpd14H+ax2jiw241Iy4MHZgUrgGarr VeuyKsQWeF366Wv/nJZ7RAg80kQGJMhsjshHQiJ9fo9qSsw7JA2z6U4pmzivot1j+it5 MF//8RiAY2w/N7U+4F8P9y2m2BADt1uIi0pqP7tw/9RsWIthcJc/T5VSlJdmNQCQ3XIi bXAA== X-Gm-Message-State: AJIora92hjClm7TNH3jvUHTs8HEI6UJWoePmG+5cbZZqo3Bun4CJBysN Xmgd1PQrkbry786YtZ2qSqoDXXaagvMBmWq5CpEEPHfujCR0dQM96170At12JoPcP2xaNTgsZ4I DshugzciP1TC7w1Ooy7FNgXsb X-Received: by 2002:a05:6638:3802:b0:32e:3d9a:9817 with SMTP id i2-20020a056638380200b0032e3d9a9817mr3381399jav.206.1655933828963; Wed, 22 Jun 2022 14:37:08 -0700 (PDT) X-Google-Smtp-Source: AGRyM1sef3p8Uu7ssABriH3qblNDoH/AkpKRoJmrO09ZGEgP+PL9or7LCLMx+soJFip3k0p/jz0afA== X-Received: by 2002:a05:6638:3802:b0:32e:3d9a:9817 with SMTP id i2-20020a056638380200b0032e3d9a9817mr3381390jav.206.1655933828779; Wed, 22 Jun 2022 14:37:08 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id g7-20020a0566380c4700b00339d892cc89sm1510446jal.83.2022.06.22.14.37.05 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 22 Jun 2022 14:37:07 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterx@redhat.com, Paolo Bonzini , Andrew Morton , David Hildenbrand , "Dr . David Alan Gilbert" , Andrea Arcangeli , Linux MM Mailing List , Sean Christopherson Subject: [PATCH 3/4] kvm: Add new pfn error KVM_PFN_ERR_INTR Date: Wed, 22 Jun 2022 17:36:55 -0400 Message-Id: <20220622213656.81546-4-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220622213656.81546-1-peterx@redhat.com> References: <20220622213656.81546-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add one new PFN error type to show when we cannot finish fetching the PFN due to interruptions. For example, by receiving a generic signal. This prepares KVM to be able to respond to SIGUSR1 (for QEMU that's the SIGIPI) even during e.g. handling an userfaultfd page fault. Signed-off-by: Peter Xu --- include/linux/kvm_host.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index b646b6fcaec6..4f84a442f67f 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -96,6 +96,7 @@ #define KVM_PFN_ERR_FAULT (KVM_PFN_ERR_MASK) #define KVM_PFN_ERR_HWPOISON (KVM_PFN_ERR_MASK + 1) #define KVM_PFN_ERR_RO_FAULT (KVM_PFN_ERR_MASK + 2) +#define KVM_PFN_ERR_INTR (KVM_PFN_ERR_MASK + 3) =20 /* * error pfns indicate that the gfn is in slot but faild to @@ -106,6 +107,16 @@ static inline bool is_error_pfn(kvm_pfn_t pfn) return !!(pfn & KVM_PFN_ERR_MASK); } =20 +/* + * When KVM_PFN_ERR_INTR is returned, it means we're interrupted during + * fetching the PFN (e.g. a signal might have arrived), so we may want to + * retry at some later point and kick the userspace to handle the signal. + */ +static inline bool is_intr_pfn(kvm_pfn_t pfn) +{ + return pfn =3D=3D KVM_PFN_ERR_INTR; +} + /* * error_noslot pfns indicate that the gfn can not be * translated to pfn - it is not in slot or failed to --=20 2.32.0 From nobody Mon Apr 20 02:56:14 2026 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 ED205C43334 for ; Wed, 22 Jun 2022 21:37:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236323AbiFVVh0 (ORCPT ); Wed, 22 Jun 2022 17:37:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233713AbiFVVhS (ORCPT ); Wed, 22 Jun 2022 17:37:18 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 5A62F36308 for ; Wed, 22 Jun 2022 14:37:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1655933832; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+Bc6oiDMKyczPP3MnRg+YG2Ibpmu1/F27D1fgoc2Uo0=; b=elRe8AFG2Ryml0dZVEwN/7ZYwX/L6A49SBv3pr55f6mL00BamfE+01/fIBPDP63ahCMVW4 4Mx6qkSDZLJE1rWSouzrmAIkatKK+aPuKktqNHyZVKEqRHvUvN/5/wEHDX15Dsg/eAEXR9 4WnRNLwjVZf6oAkqxqlBdCJM9zRX8jQ= Received: from mail-io1-f69.google.com (mail-io1-f69.google.com [209.85.166.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-599-Y822-L91OI2pCns4Cl3yjQ-1; Wed, 22 Jun 2022 17:37:11 -0400 X-MC-Unique: Y822-L91OI2pCns4Cl3yjQ-1 Received: by mail-io1-f69.google.com with SMTP id e195-20020a6bb5cc000000b0066cc9ece80fso9867419iof.5 for ; Wed, 22 Jun 2022 14:37:11 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+Bc6oiDMKyczPP3MnRg+YG2Ibpmu1/F27D1fgoc2Uo0=; b=VxZugiYUTfoIAX85wk5vc+W+mxZcqaM937xuIPu4l7cPQSZt6/9XnmFpPrLbpLcBFY 5iYjS06JajXVBzOriEOemgb+zINdbJXCZOxbRpUeFI8JcSlD3ydf/55JMEM5EtrvROsD jsb5HBmTRzP3mgxZqnm3WywWNHQ9UXuRiwacdNqaLZQnJHvx1v5Sal3lAI4wPKGMFodZ 0ILnlpbAF8W63V2/83GsUXfy87IkWPFhjjMo69AeW/sdc+2augXEf0BM/ivWjlEjWlrr r+4isnpjSMKaAXSI1HNwTo82o39nQYKSon0hEqLEdbFE2/YJjvyJwft2IBm4IL0+ztGQ i5HQ== X-Gm-Message-State: AJIora9VnzYmyzR0CP+TtlDARAHG6+krcWNfHQm0zhK2o58PPoGfso+b xGGxx6RAEefuGmAuUi20NunpyopuZcbbG+TPpnkE4fqybRrpGPcqeIt7xxxHbJrOsmNSDVgs5UB 6KuuE5C2iGieCx6qTBfHaO8E7 X-Received: by 2002:a05:6638:3043:b0:314:7ce2:4a6e with SMTP id u3-20020a056638304300b003147ce24a6emr3407084jak.258.1655933830725; Wed, 22 Jun 2022 14:37:10 -0700 (PDT) X-Google-Smtp-Source: AGRyM1tXYF1gATLPxilQ8J8azYs80FKmrYKCExwZSpp2Y52+zhUd9Cgm+xA8CMppEVs8Il5ycEHTqA== X-Received: by 2002:a05:6638:3043:b0:314:7ce2:4a6e with SMTP id u3-20020a056638304300b003147ce24a6emr3407077jak.258.1655933830514; Wed, 22 Jun 2022 14:37:10 -0700 (PDT) Received: from localhost.localdomain (cpec09435e3e0ee-cmc09435e3e0ec.cpe.net.cable.rogers.com. [99.241.198.116]) by smtp.gmail.com with ESMTPSA id g7-20020a0566380c4700b00339d892cc89sm1510446jal.83.2022.06.22.14.37.08 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 22 Jun 2022 14:37:09 -0700 (PDT) From: Peter Xu To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Cc: peterx@redhat.com, Paolo Bonzini , Andrew Morton , David Hildenbrand , "Dr . David Alan Gilbert" , Andrea Arcangeli , Linux MM Mailing List , Sean Christopherson Subject: [PATCH 4/4] kvm/x86: Allow to respond to generic signals during slow page faults Date: Wed, 22 Jun 2022 17:36:56 -0400 Message-Id: <20220622213656.81546-5-peterx@redhat.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220622213656.81546-1-peterx@redhat.com> References: <20220622213656.81546-1-peterx@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" All the facilities should be ready for this, what we need to do is to add a new KVM_GTP_INTERRUPTIBLE flag showing that we're willing to be interrupted by common signals during the __gfn_to_pfn_memslot() request, and wire it up with a FOLL_INTERRUPTIBLE flag that we've just introduced. Note that only x86 slow page fault routine will set this new bit. The new bit is not used in non-x86 arch or on other gup paths even for x86. However it can actually be used elsewhere too but not yet covered. When we see the PFN fetching was interrupted, do early exit to userspace with an KVM_EXIT_INTR exit reason. Signed-off-by: Peter Xu --- arch/x86/kvm/mmu/mmu.c | 9 +++++++++ include/linux/kvm_host.h | 1 + virt/kvm/kvm_main.c | 4 ++++ 3 files changed, 14 insertions(+) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index e92f1ab63d6a..b39acb7cb16d 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -3012,6 +3012,13 @@ static int kvm_handle_bad_page(struct kvm_vcpu *vcpu= , gfn_t gfn, kvm_pfn_t pfn) static int handle_abnormal_pfn(struct kvm_vcpu *vcpu, struct kvm_page_faul= t *fault, unsigned int access) { + /* NOTE: not all error pfn is fatal; handle intr before the other ones */ + if (unlikely(is_intr_pfn(fault->pfn))) { + vcpu->run->exit_reason =3D KVM_EXIT_INTR; + ++vcpu->stat.signal_exits; + return -EINTR; + } + /* The pfn is invalid, report the error! */ if (unlikely(is_error_pfn(fault->pfn))) return kvm_handle_bad_page(vcpu, fault->gfn, fault->pfn); @@ -4017,6 +4024,8 @@ static int kvm_faultin_pfn(struct kvm_vcpu *vcpu, str= uct kvm_page_fault *fault) } } =20 + /* Allow to respond to generic signals in slow page faults */ + flags |=3D KVM_GTP_INTERRUPTIBLE; fault->pfn =3D __gfn_to_pfn_memslot(slot, fault->gfn, flags, NULL, &fault->map_writable, &fault->hva); return RET_PF_CONTINUE; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 4f84a442f67f..c8d98e435537 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1163,6 +1163,7 @@ typedef unsigned int __bitwise kvm_gtp_flag_t; =20 #define KVM_GTP_WRITE ((__force kvm_gtp_flag_t) BIT(0)) #define KVM_GTP_ATOMIC ((__force kvm_gtp_flag_t) BIT(1)) +#define KVM_GTP_INTERRUPTIBLE ((__force kvm_gtp_flag_t) BIT(2)) =20 kvm_pfn_t __gfn_to_pfn_memslot(const struct kvm_memory_slot *slot, gfn_t g= fn, kvm_gtp_flag_t gtp_flags, bool *async, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 952400b42ee9..b3873cac5672 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2462,6 +2462,8 @@ static int hva_to_pfn_slow(unsigned long addr, bool *= async, flags |=3D FOLL_WRITE; if (async) flags |=3D FOLL_NOWAIT; + if (gtp_flags & KVM_GTP_INTERRUPTIBLE) + flags |=3D FOLL_INTERRUPTIBLE; =20 npages =3D get_user_pages_unlocked(addr, 1, &page, flags); if (npages !=3D 1) @@ -2599,6 +2601,8 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, kvm_gtp_flag= _t gtp_flags, bool *async, npages =3D hva_to_pfn_slow(addr, async, gtp_flags, writable, &pfn); if (npages =3D=3D 1) return pfn; + if (npages =3D=3D -EINTR) + return KVM_PFN_ERR_INTR; =20 mmap_read_lock(current->mm); if (npages =3D=3D -EHWPOISON || --=20 2.32.0