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 X-Spam-Level: X-Spam-Status: No, score=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 453AFC433DB for ; Mon, 4 Jan 2021 05:36:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E34D62087E for ; Mon, 4 Jan 2021 05:36:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727737AbhADFgW (ORCPT ); Mon, 4 Jan 2021 00:36:22 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:60715 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725830AbhADFgW (ORCPT ); Mon, 4 Jan 2021 00:36:22 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1609738494; 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=d+9NkcOQX9yEPejfJ84tb0DvqSa3inovTpkQySkaX+I=; b=Rvc0+pVeU4SrWBXAUJ/yLO1zG4/lQFFs8q+qR992eo65Ty2ZZVvKqTz914pJU+OWPGV/Gy VN23dcCPRO6/YFdd+l7LF05BEOSCQ37dk4n5hmE6xCYl9Hh6ukjI0QkR08b7oA6TpRvfaj 6eMrihbLuXx2d/WX1nmFpvvoX0SXXT4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-121-eOl7pfvLOqqBbQyEcRFOpg-1; Mon, 04 Jan 2021 00:34:52 -0500 X-MC-Unique: eOl7pfvLOqqBbQyEcRFOpg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 57720180A093; Mon, 4 Jan 2021 05:34:51 +0000 (UTC) Received: from [10.72.13.91] (ovpn-13-91.pek2.redhat.com [10.72.13.91]) by smtp.corp.redhat.com (Postfix) with ESMTP id C19C15D719; Mon, 4 Jan 2021 05:34:45 +0000 (UTC) Subject: Re: [RFC 1/2] KVM: add initial support for KVM_SET_IOREGION To: Elena Afanasova , kvm@vger.kernel.org Cc: stefanha@redhat.com, jag.raman@oracle.com, elena.ufimtseva@oracle.com References: <0cc68c81d6fae042d8a84bf90dd77eecd4da7cc8.camel@gmail.com> From: Jason Wang Message-ID: <947ba980-f870-16fb-2ea5-07da617d6bb6@redhat.com> Date: Mon, 4 Jan 2021 13:34:43 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <0cc68c81d6fae042d8a84bf90dd77eecd4da7cc8.camel@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 2021/1/4 上午4:32, Elena Afanasova wrote: > On Thu, 2020-12-31 at 11:45 +0800, Jason Wang wrote: >> On 2020/12/29 下午6:02, Elena Afanasova wrote: >>> This vm ioctl adds or removes an ioregionfd MMIO/PIO region. >> How about FAST_MMIO? >> > I’ll add KVM_IOREGION_FAST_MMIO flag support. So this may be suitable > for triggers which could use posted writes. The struct ioregionfd_cmd > size bits and the data field will be unused in this case. Note that eventfd checks for length and have datamatch support. Do we need to do something similar. I guess the idea is to have a generic interface to let eventfd work for ioregion as well. > >>> Guest >>> read and write accesses are dispatched through the given ioregionfd >>> instead of returning from ioctl(KVM_RUN). Regions can be deleted by >>> setting fds to -1. >>> >>> Signed-off-by: Elena Afanasova >>> --- >>> arch/x86/kvm/Kconfig | 1 + >>> arch/x86/kvm/Makefile | 1 + >>> arch/x86/kvm/x86.c | 1 + >>> include/linux/kvm_host.h | 17 +++ >>> include/uapi/linux/kvm.h | 23 ++++ >>> virt/kvm/Kconfig | 3 + >>> virt/kvm/eventfd.c | 25 +++++ >>> virt/kvm/eventfd.h | 14 +++ >>> virt/kvm/ioregion.c | 233 >>> +++++++++++++++++++++++++++++++++++++++ >>> virt/kvm/ioregion.h | 15 +++ >>> virt/kvm/kvm_main.c | 20 +++- >>> 11 files changed, 350 insertions(+), 3 deletions(-) >>> create mode 100644 virt/kvm/eventfd.h >>> create mode 100644 virt/kvm/ioregion.c >>> create mode 100644 virt/kvm/ioregion.h >>> >>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig >>> index f92dfd8ef10d..b914ef375199 100644 >>> --- a/arch/x86/kvm/Kconfig >>> +++ b/arch/x86/kvm/Kconfig >>> @@ -33,6 +33,7 @@ config KVM >>> select HAVE_KVM_IRQ_BYPASS >>> select HAVE_KVM_IRQ_ROUTING >>> select HAVE_KVM_EVENTFD >>> + select KVM_IOREGION >>> select KVM_ASYNC_PF >>> select USER_RETURN_NOTIFIER >>> select KVM_MMIO >>> diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile >>> index b804444e16d4..b3b17dc9f7d4 100644 >>> --- a/arch/x86/kvm/Makefile >>> +++ b/arch/x86/kvm/Makefile >>> @@ -12,6 +12,7 @@ KVM := ../../../virt/kvm >>> kvm-y += $(KVM)/kvm_main.o >>> $(KVM)/coalesced_mmio.o \ >>> $(KVM)/eventfd.o $(KVM)/irqchip.o >>> $(KVM)/vfio.o >>> kvm-$(CONFIG_KVM_ASYNC_PF) += $(KVM)/async_pf.o >>> +kvm-$(CONFIG_KVM_IOREGION) += $(KVM)/ioregion.o >>> >>> kvm-y += x86.o emulate.o i8259.o irq.o >>> lapic.o \ >>> i8254.o ioapic.o irq_comm.o cpuid.o pmu.o >>> mtrr.o \ >>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >>> index e545a8a613b1..ddb28f5ca252 100644 >>> --- a/arch/x86/kvm/x86.c >>> +++ b/arch/x86/kvm/x86.c >>> @@ -3739,6 +3739,7 @@ int kvm_vm_ioctl_check_extension(struct kvm >>> *kvm, long ext) >>> case KVM_CAP_X86_USER_SPACE_MSR: >>> case KVM_CAP_X86_MSR_FILTER: >>> case KVM_CAP_ENFORCE_PV_FEATURE_CPUID: >>> + case KVM_CAP_IOREGIONFD: >>> r = 1; >>> break; >>> case KVM_CAP_SYNC_REGS: >>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h >>> index 7f2e2a09ebbd..7cd667dddba9 100644 >>> --- a/include/linux/kvm_host.h >>> +++ b/include/linux/kvm_host.h >>> @@ -470,6 +470,10 @@ struct kvm { >>> struct mutex resampler_lock; >>> } irqfds; >>> struct list_head ioeventfds; >>> +#endif >>> +#ifdef CONFIG_KVM_IOREGION >>> + struct list_head ioregions_mmio; >>> + struct list_head ioregions_pio; >>> #endif >>> struct kvm_vm_stat stat; >>> struct kvm_arch arch; >>> @@ -1262,6 +1266,19 @@ static inline int kvm_ioeventfd(struct kvm >>> *kvm, struct kvm_ioeventfd *args) >>> >>> #endif /* CONFIG_HAVE_KVM_EVENTFD */ >>> >>> +#ifdef CONFIG_KVM_IOREGION >>> +void kvm_ioregionfd_init(struct kvm *kvm); >>> +int kvm_ioregionfd(struct kvm *kvm, struct kvm_ioregion *args); >>> + >>> +#else >>> + >>> +static inline void kvm_ioregionfd_init(struct kvm *kvm) {} >>> +static inline int kvm_ioregionfd(struct kvm *kvm, struct >>> kvm_ioregion *args) >>> +{ >>> + return -ENOSYS; >>> +} >>> +#endif >>> + >>> void kvm_arch_irq_routing_update(struct kvm *kvm); >>> >>> static inline void kvm_make_request(int req, struct kvm_vcpu >>> *vcpu) >>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >>> index ca41220b40b8..81e775778c66 100644 >>> --- a/include/uapi/linux/kvm.h >>> +++ b/include/uapi/linux/kvm.h >>> @@ -732,6 +732,27 @@ struct kvm_ioeventfd { >>> __u8 pad[36]; >>> }; >>> >>> +enum { >>> + kvm_ioregion_flag_nr_pio, >>> + kvm_ioregion_flag_nr_posted_writes, >>> + kvm_ioregion_flag_nr_max, >>> +}; >>> + >>> +#define KVM_IOREGION_PIO (1 << kvm_ioregion_flag_nr_pio) >>> +#define KVM_IOREGION_POSTED_WRITES (1 << >>> kvm_ioregion_flag_nr_posted_writes) >>> + >>> +#define KVM_IOREGION_VALID_FLAG_MASK ((1 << >>> kvm_ioregion_flag_nr_max) - 1) >>> + >>> +struct kvm_ioregion { >>> + __u64 guest_paddr; /* guest physical address */ >>> + __u64 memory_size; /* bytes */ >>> + __u64 user_data; >> What will this field do? Is it a token? >> > Yes, it’s an opaque token that can be used by userspace in order to > determine which MemoryRegion to dispatch. This part I don't understand. Userspace should know the fd number (which I guess should be sufficient?). > >>> + __s32 rfd; >>> + __s32 wfd; >>> + __u32 flags; >>> + __u8 pad[28]; >>> +}; >> Is this possible to register the same fd with multiple GPA ranges? >> If >> not, do we need to check for fd collision? >> > Yes, it’s possible to register the same fd with multiple GPA ranges. > >>> + >>> #define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0) >>> #define KVM_X86_DISABLE_EXITS_HLT (1 << 1) >>> #define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) >>> @@ -1053,6 +1074,7 @@ struct kvm_ppc_resize_hpt { >>> #define KVM_CAP_X86_USER_SPACE_MSR 188 >>> #define KVM_CAP_X86_MSR_FILTER 189 >>> #define KVM_CAP_ENFORCE_PV_FEATURE_CPUID 190 >>> +#define KVM_CAP_IOREGIONFD 191 >>> >>> #ifdef KVM_CAP_IRQ_ROUTING >>> >>> @@ -1308,6 +1330,7 @@ struct kvm_vfio_spapr_tce { >>> struct >>> kvm_userspace_memory_region) >>> #define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47) >>> #define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO, 0x48, __u64) >>> +#define KVM_SET_IOREGION _IOW(KVMIO, 0x49, struct >>> kvm_ioregion) >>> >>> /* enable ucontrol for s390 */ >>> struct kvm_s390_ucas_mapping { >>> diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig >>> index 1c37ccd5d402..5e6620bbf000 100644 >>> --- a/virt/kvm/Kconfig >>> +++ b/virt/kvm/Kconfig >>> @@ -17,6 +17,9 @@ config HAVE_KVM_EVENTFD >>> bool >>> select EVENTFD >>> >>> +config KVM_IOREGION >>> + bool >>> + >>> config KVM_MMIO >>> bool >>> >>> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c >>> index c2323c27a28b..aadb73903f8b 100644 >>> --- a/virt/kvm/eventfd.c >>> +++ b/virt/kvm/eventfd.c >>> @@ -27,6 +27,7 @@ >>> #include >>> >>> #include >>> +#include "ioregion.h" >>> >>> #ifdef CONFIG_HAVE_KVM_IRQFD >>> >>> @@ -755,6 +756,23 @@ static const struct kvm_io_device_ops >>> ioeventfd_ops = { >>> .destructor = ioeventfd_destructor, >>> }; >>> >>> +#ifdef CONFIG_KVM_IOREGION >>> +/* assumes kvm->slots_lock held */ >>> +bool kvm_eventfd_collides(struct kvm *kvm, int bus_idx, >>> + u64 start, u64 size) >>> +{ >>> + struct _ioeventfd *_p; >>> + >>> + list_for_each_entry(_p, &kvm->ioeventfds, list) >>> + if (_p->bus_idx == bus_idx && >>> + overlap(start, size, _p->addr, >>> + !_p->length ? 8 : _p->length)) >>> + return true; >>> + >>> + return false; >>> +} >>> +#endif >>> + >>> /* assumes kvm->slots_lock held */ >>> static bool >>> ioeventfd_check_collision(struct kvm *kvm, struct _ioeventfd *p) >>> @@ -770,6 +788,13 @@ ioeventfd_check_collision(struct kvm *kvm, >>> struct _ioeventfd *p) >>> _p->datamatch == p->datamatch)))) >>> return true; >>> >>> +#ifdef CONFIG_KVM_IOREGION >>> + if (p->bus_idx == KVM_MMIO_BUS || p->bus_idx == KVM_PIO_BUS) >>> + if (kvm_ioregion_collides(kvm, p->bus_idx, p->addr, >>> + !p->length ? 8 : p->length)) >>> + return true; >>> +#endif >>> + >>> return false; >>> } >>> >>> diff --git a/virt/kvm/eventfd.h b/virt/kvm/eventfd.h >>> new file mode 100644 >>> index 000000000000..73a621eebae3 >>> --- /dev/null >>> +++ b/virt/kvm/eventfd.h >>> @@ -0,0 +1,14 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> +#ifndef __KVM_EVENTFD_H__ >>> +#define __KVM_EVENTFD_H__ >>> + >>> +#ifdef CONFIG_KVM_IOREGION >>> +bool kvm_eventfd_collides(struct kvm *kvm, int bus_idx, u64 start, >>> u64 size); >>> +#else >>> +static inline bool >>> +kvm_eventfd_collides(struct kvm *kvm, int bus_idx, u64 start, u64 >>> size) >>> +{ >>> + return false; >>> +} >>> +#endif >>> +#endif >>> diff --git a/virt/kvm/ioregion.c b/virt/kvm/ioregion.c >>> new file mode 100644 >>> index 000000000000..a200c3761343 >>> --- /dev/null >>> +++ b/virt/kvm/ioregion.c >>> @@ -0,0 +1,233 @@ >>> +// SPDX-License-Identifier: GPL-2.0-only >>> +#include >>> +#include >>> +#include >>> +#include "eventfd.h" >>> + >>> +void >>> +kvm_ioregionfd_init(struct kvm *kvm) >>> +{ >>> + INIT_LIST_HEAD(&kvm->ioregions_mmio); >>> + INIT_LIST_HEAD(&kvm->ioregions_pio); >>> +} >>> + >>> +struct ioregion { >>> + struct list_head list; >>> + u64 paddr; >>> + u64 size; >>> + struct file *rf; >>> + struct file *wf; >>> + u64 user_data; >>> + struct kvm_io_device dev; >>> + bool posted_writes; >>> +}; >>> + >>> +static inline struct ioregion * >>> +to_ioregion(struct kvm_io_device *dev) >>> +{ >>> + return container_of(dev, struct ioregion, dev); >>> +} >>> + >>> +/* assumes kvm->slots_lock held */ >>> +static void >>> +ioregion_release(struct ioregion *p) >>> +{ >>> + fput(p->rf); >>> + fput(p->wf); >>> + list_del(&p->list); >>> + kfree(p); >>> +} >>> + >>> +static int >>> +ioregion_read(struct kvm_vcpu *vcpu, struct kvm_io_device *this, >>> gpa_t addr, >>> + int len, void *val) >>> +{ >>> + return 0; >>> +} >>> + >>> +static int >>> +ioregion_write(struct kvm_vcpu *vcpu, struct kvm_io_device *this, >>> gpa_t addr, >>> + int len, const void *val) >>> +{ >>> + return 0; >>> +} >>> + >>> +/* >>> + * This function is called as KVM is completely shutting down. We >>> do not >>> + * need to worry about locking just nuke anything we have as >>> quickly as possible >>> + */ >>> +static void >>> +ioregion_destructor(struct kvm_io_device *this) >>> +{ >>> + struct ioregion *p = to_ioregion(this); >>> + >>> + ioregion_release(p); >>> +} >>> + >>> +static const struct kvm_io_device_ops ioregion_ops = { >>> + .read = ioregion_read, >>> + .write = ioregion_write, >>> + .destructor = ioregion_destructor, >>> +}; >>> + >>> +static inline struct list_head * >>> +get_ioregion_list(struct kvm *kvm, enum kvm_bus bus_idx) >>> +{ >>> + return (bus_idx == KVM_MMIO_BUS) ? >>> + &kvm->ioregions_mmio : &kvm->ioregions_pio; >>> +} >>> + >>> +/* check for not overlapping case and reverse */ >>> +inline bool >>> +overlap(u64 start1, u64 size1, u64 start2, u64 size2) >>> +{ >>> + u64 end1 = start1 + size1 - 1; >>> + u64 end2 = start2 + size2 - 1; >>> + >>> + return !(end1 < start2 || start1 >= end2); >>> +} >>> + >>> +/* assumes kvm->slots_lock held */ >>> +bool >>> +kvm_ioregion_collides(struct kvm *kvm, int bus_idx, >>> + u64 start, u64 size) >>> +{ >>> + struct ioregion *_p; >>> + struct list_head *ioregions; >>> + >>> + ioregions = get_ioregion_list(kvm, bus_idx); >>> + list_for_each_entry(_p, ioregions, list) >>> + if (overlap(start, size, _p->paddr, _p->size)) >>> + return true; >>> + >>> + return false; >>> +} >>> + >>> +/* assumes kvm->slots_lock held */ >>> +static bool >>> +ioregion_collision(struct kvm *kvm, struct ioregion *p, enum >>> kvm_bus bus_idx) >>> +{ >>> + if (kvm_ioregion_collides(kvm, bus_idx, p->paddr, p->size) || >>> + kvm_eventfd_collides(kvm, bus_idx, p->paddr, p->size)) >>> + return true; >>> + >>> + return false; >>> +} >>> + >>> +static enum kvm_bus >>> +get_bus_from_flags(__u32 flags) >>> +{ >>> + if (flags & KVM_IOREGION_PIO) >>> + return KVM_PIO_BUS; >>> + return KVM_MMIO_BUS; >>> +} >>> + >>> +int >>> +kvm_set_ioregion(struct kvm *kvm, struct kvm_ioregion *args) >>> +{ >>> + struct ioregion *p; >>> + bool is_posted_writes; >>> + struct file *rfile, *wfile; >>> + enum kvm_bus bus_idx; >>> + int ret = 0; >>> + >>> + if (!args->memory_size) >>> + return -EINVAL; >>> + if ((args->guest_paddr + args->memory_size - 1) < args- >>>> guest_paddr) >>> + return -EINVAL; >>> + if (args->flags & ~KVM_IOREGION_VALID_FLAG_MASK) >>> + return -EINVAL; >>> + >>> + rfile = fget(args->rfd); >>> + if (!rfile) >>> + return -EBADF; >>> + wfile = fget(args->wfd); >>> + if (!wfile) { >>> + fput(rfile); >>> + return -EBADF; >>> + } >>> + if ((rfile->f_flags & O_NONBLOCK) || (wfile->f_flags & >>> O_NONBLOCK)) { >>> + ret = -EINVAL; >>> + goto fail; >>> + } >> Instead of checking nonblocking, can we poll here? >> > Yes, it’s possible. It would be necessary in the case of out-of-order > requests. But since multiple in-flight messages don’t seem to be a use > case I’m not sure if it’s necessary. Typically device register accesses > should not take a long time, so making them asynchronous doesn't seem > like a practical advantage. Also this might complicate the code and > make it slower. What do you think? One issue I saw is that, if we register a single fd for e.g two regions. And those two regions were read in parallel from guest. It looks to me we don't have any synchronization in the current code. > >>> + p = kzalloc(sizeof(*p), GFP_KERNEL_ACCOUNT); >>> + if (!p) { >>> + ret = -ENOMEM; >>> + goto fail; >>> + } >>> + >>> + INIT_LIST_HEAD(&p->list); >>> + p->paddr = args->guest_paddr; >>> + p->size = args->memory_size; >>> + p->user_data = args->user_data; >>> + p->rf = rfile; >>> + p->wf = wfile; >>> + is_posted_writes = args->flags & KVM_IOREGION_POSTED_WRITES; >>> + p->posted_writes = is_posted_writes ? true : false; >>> + bus_idx = get_bus_from_flags(args->flags); >>> + >>> + mutex_lock(&kvm->slots_lock); >>> + >>> + if (ioregion_collision(kvm, p, bus_idx)) { >>> + ret = -EEXIST; >>> + goto unlock_fail; >>> + } >>> + kvm_iodevice_init(&p->dev, &ioregion_ops); >>> + ret = kvm_io_bus_register_dev(kvm, bus_idx, p->paddr, p->size, >>> + &p->dev); >>> + if (ret < 0) >>> + goto unlock_fail; >> We probably need to register to FAST_MMIO when bus_idx is MMIO. >> >> >>> + list_add_tail(&p->list, get_ioregion_list(kvm, bus_idx)); >>> + >>> + mutex_unlock(&kvm->slots_lock); >>> + >>> + return 0; >>> + >>> +unlock_fail: >>> + mutex_unlock(&kvm->slots_lock); >>> + kfree(p); >>> +fail: >>> + fput(rfile); >>> + fput(wfile); >>> + >>> + return ret; >>> +} >>> + >>> +static int >>> +kvm_rm_ioregion(struct kvm *kvm, struct kvm_ioregion *args) >>> +{ >>> + struct ioregion *p, *tmp; >>> + enum kvm_bus bus_idx; >>> + int ret = -ENOENT; >>> + struct list_head *ioregions; >>> + >>> + if (args->rfd != -1 || args->wfd != -1) >>> + return -EINVAL; >> If we want to use ioregion fd for doorbell, rfd is probably not >> necessary here. >> > This condition is simply a requirement that region can be deleted in > the case of both fds are set to -1. Ok. Thanks > >> Thanks >> >> >>> + >>> + bus_idx = get_bus_from_flags(args->flags); >>> + ioregions = get_ioregion_list(kvm, bus_idx); >>> + >>> + mutex_lock(&kvm->slots_lock); >>> + >>> + list_for_each_entry_safe(p, tmp, ioregions, list) { >>> + if (p->paddr == args->guest_paddr && >>> + p->size == args->memory_size) { >>> + kvm_io_bus_unregister_dev(kvm, bus_idx, &p- >>>> dev); >>> + ioregion_release(p); >>> + ret = 0; >>> + break; >>> + } >>> + } >>> + >>> + mutex_unlock(&kvm->slots_lock); >>> + >>> + return ret; >>> +} >>> + >>> +int >>> +kvm_ioregionfd(struct kvm *kvm, struct kvm_ioregion *args) >>> +{ >>> + if (args->rfd == -1 || args->wfd == -1) >>> + return kvm_rm_ioregion(kvm, args); >>> + return kvm_set_ioregion(kvm, args); >>> +} >>> diff --git a/virt/kvm/ioregion.h b/virt/kvm/ioregion.h >>> new file mode 100644 >>> index 000000000000..23ffa812ec7a >>> --- /dev/null >>> +++ b/virt/kvm/ioregion.h >>> @@ -0,0 +1,15 @@ >>> +/* SPDX-License-Identifier: GPL-2.0-only */ >>> +#ifndef __KVM_IOREGION_H__ >>> +#define __KVM_IOREGION_H__ >>> + >>> +#ifdef CONFIG_KVM_IOREGION >>> +inline bool overlap(u64 start1, u64 size1, u64 start2, u64 size2); >>> +bool kvm_ioregion_collides(struct kvm *kvm, int bus_idx, u64 >>> start, u64 size); >>> +#else >>> +static inline bool >>> +kvm_ioregion_collides(struct kvm *kvm, int bus_idx, u64 start, u64 >>> size) >>> +{ >>> + return false; >>> +} >>> +#endif >>> +#endif >>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >>> index 2541a17ff1c4..385d8ec6350d 100644 >>> --- a/virt/kvm/kvm_main.c >>> +++ b/virt/kvm/kvm_main.c >>> @@ -747,6 +747,7 @@ static struct kvm *kvm_create_vm(unsigned long >>> type) >>> mmgrab(current->mm); >>> kvm->mm = current->mm; >>> kvm_eventfd_init(kvm); >>> + kvm_ioregionfd_init(kvm); >>> mutex_init(&kvm->lock); >>> mutex_init(&kvm->irq_lock); >>> mutex_init(&kvm->slots_lock); >>> @@ -3708,6 +3709,16 @@ static long kvm_vm_ioctl(struct file *filp, >>> r = kvm_vm_ioctl_set_memory_region(kvm, >>> &kvm_userspace_mem); >>> break; >>> } >>> + case KVM_SET_IOREGION: { >>> + struct kvm_ioregion data; >>> + >>> + r = -EFAULT; >>> + if (copy_from_user(&data, argp, sizeof(data))) >>> + goto out; >>> + >>> + r = kvm_ioregionfd(kvm, &data); >>> + break; >>> + } >>> case KVM_GET_DIRTY_LOG: { >>> struct kvm_dirty_log log; >>> >>> @@ -4301,9 +4312,12 @@ int kvm_io_bus_register_dev(struct kvm *kvm, >>> enum kvm_bus bus_idx, gpa_t addr, >>> if (!bus) >>> return -ENOMEM; >>> >>> - /* exclude ioeventfd which is limited by maximum fd */ >>> - if (bus->dev_count - bus->ioeventfd_count > NR_IOBUS_DEVS - 1) >>> - return -ENOSPC; >>> + /* enforce hard limit if kmemcg is disabled and >>> + * exclude ioeventfd which is limited by maximum fd >>> + */ >>> + if (!memcg_kmem_enabled()) >>> + if (bus->dev_count - bus->ioeventfd_count > >>> NR_IOBUS_DEVS - 1) >>> + return -ENOSPC; >>> >>> new_bus = kmalloc(struct_size(bus, range, bus->dev_count + 1), >>> GFP_KERNEL_ACCOUNT);