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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id y4sm183153wmj.2.2020.11.16.10.20.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Nov 2020 10:20:22 -0800 (PST) Subject: Re: [PATCH] util/vfio-helpers.c: Use ram_block_discard_disable() in qemu_vfio_open_pci() To: David Hildenbrand , qemu-devel@nongnu.org References: <20201116105947.9194-1-david@redhat.com> From: Paolo Bonzini Message-ID: <996cb0a2-f0ce-32bb-efcc-64da9964c518@redhat.com> Date: Mon, 16 Nov 2020 19:20:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: <20201116105947.9194-1-david@redhat.com> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=63.128.21.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/11/16 04:46:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Pankaj Gupta , "Michael S. Tsirkin" , "Dr . David Alan Gilbert" , Peter Xu , Alex Williamson , Wei Yang , Igor Mammedov Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 16/11/20 11:59, David Hildenbrand wrote: > Currently, when using "nvme://" for a block device, like > -drive file=nvme://0000:01:00.0/1,if=none,id=drive0 \ > -device virtio-blk,drive=drive0 \ > > VFIO may pin all guest memory, and discarding of RAM no longer works as > expected. I was able to reproduce this easily with my > 01:00.0 Non-Volatile memory controller: Samsung Electronics Co Ltd > NVMe SSD Controller SM981/PM981/PM983 > > Similar to common VFIO, we have to disable it, making sure that: > a) virtio-balloon won't discard any memory ("silently disabled") > b) virtio-mem and nvme:// run mutually exclusive > > Cc: Paolo Bonzini > Cc: "Michael S. Tsirkin" > Cc: Alex Williamson > Cc: Wei Yang > Cc: Dr. David Alan Gilbert > Cc: Igor Mammedov > Cc: Pankaj Gupta > Cc: Peter Xu > Signed-off-by: David Hildenbrand > --- > stubs/ram-block.c | 6 ++++++ > util/vfio-helpers.c | 14 ++++++++++++++ > 2 files changed, 20 insertions(+) > > diff --git a/stubs/ram-block.c b/stubs/ram-block.c > index 73c0a3ee08..108197683b 100644 > --- a/stubs/ram-block.c > +++ b/stubs/ram-block.c > @@ -1,6 +1,7 @@ > #include "qemu/osdep.h" > #include "exec/ramlist.h" > #include "exec/cpu-common.h" > +#include "exec/memory.h" > > void *qemu_ram_get_host_addr(RAMBlock *rb) > { > @@ -29,3 +30,8 @@ int qemu_ram_foreach_block(RAMBlockIterFunc func, void *opaque) > { > return 0; > } > + > +int ram_block_discard_disable(bool state) > +{ > + return 0; > +} > diff --git a/util/vfio-helpers.c b/util/vfio-helpers.c > index c469beb061..2bec48e163 100644 > --- a/util/vfio-helpers.c > +++ b/util/vfio-helpers.c > @@ -16,6 +16,7 @@ > #include "qapi/error.h" > #include "exec/ramlist.h" > #include "exec/cpu-common.h" > +#include "exec/memory.h" > #include "trace.h" > #include "qemu/error-report.h" > #include "standard-headers/linux/pci_regs.h" > @@ -494,8 +495,20 @@ QEMUVFIOState *qemu_vfio_open_pci(const char *device, Error **errp) > int r; > QEMUVFIOState *s = g_new0(QEMUVFIOState, 1); > > + /* > + * VFIO may pin all memory inside mappings, resulting it in pinning > + * all memory inside RAM blocks unconditionally. > + */ > + r = ram_block_discard_disable(true); > + if (r) { > + error_setg_errno(errp, -r, "Cannot set discarding of RAM broken"); > + g_free(s); > + return NULL; > + } > + > r = qemu_vfio_init_pci(s, device, errp); > if (r) { > + ram_block_discard_disable(false); > g_free(s); > return NULL; > } > @@ -837,4 +850,5 @@ void qemu_vfio_close(QEMUVFIOState *s) > close(s->device); > close(s->group); > close(s->container); > + ram_block_discard_disable(false); > } > Queued, thanks. Paolo