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Wed, 20 Mar 2024 08:56:45 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFL9lb9JU6u29HDH1ruhW2E+dvTvzRu/d44yRA/zPFQeK1CKRp96jbDh+2Z61dbYWZINepF3A== X-Received: by 2002:a17:906:fd3:b0:a46:d786:3672 with SMTP id c19-20020a1709060fd300b00a46d7863672mr79667ejk.13.1710950204786; Wed, 20 Mar 2024 08:56:44 -0700 (PDT) Received: from [192.168.10.118] ([151.95.49.219]) by smtp.googlemail.com with ESMTPSA id gf9-20020a170906e20900b00a46a27794f6sm5377774ejb.123.2024.03.20.08.56.41 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Mar 2024 08:56:42 -0700 (PDT) Message-ID: <86baf9cb-ba7b-4701-a96d-b34edfe3d1de@redhat.com> Date: Wed, 20 Mar 2024 16:56:40 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 09/49] kvm: Enable KVM_SET_USER_MEMORY_REGION2 for memslot Content-Language: en-US To: Michael Roth , qemu-devel@nongnu.org Cc: kvm@vger.kernel.org, Tom Lendacky , =?UTF-8?Q?Daniel_P_=2E_Berrang=C3=A9?= , Markus Armbruster , Pankaj Gupta , Xiaoyao Li , Isaku Yamahata , Chao Peng References: <20240320083945.991426-1-michael.roth@amd.com> <20240320083945.991426-10-michael.roth@amd.com> From: Paolo Bonzini Autocrypt: addr=pbonzini@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=pbonzini@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.417, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 3/20/24 09:39, Michael Roth wrote: > + if (cap_user_memory2 == -1) { > + cap_user_memory2 = kvm_check_extension(s, KVM_CAP_USER_MEMORY2); > + } > + > + if (!cap_user_memory2 && slot->guest_memfd >= 0) { > + error_report("%s, KVM doesn't support KVM_CAP_USER_MEMORY2," > + " which is required by guest memfd!", __func__); > + exit(1); > + } It's easier and more robust (for error reporting purposes) to check both KVM_CAP_GUEST_MEMFD and KVM_CAP_USER_MEMORY2 at once in the earlier patches: - kvm_guest_memfd_supported = kvm_check_extension(s, KVM_CAP_GUEST_MEMFD); + kvm_guest_memfd_supported = + kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) && + kvm_check_extension(s, KVM_CAP_USER_MEMORY2); since KVM cannot really support guest_memfd if it cannot then use it to create private memory slots. And then, this one can be changed to also use kvm_guest_memfd_supported: diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index e83429b31eb..afcf6f87045 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -284,19 +284,8 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot, boo { KVMState *s = kvm_state; struct kvm_userspace_memory_region2 mem; - static int cap_user_memory2 = -1; int ret; - if (cap_user_memory2 == -1) { - cap_user_memory2 = kvm_check_extension(s, KVM_CAP_USER_MEMORY2); - } - - if (!cap_user_memory2 && slot->guest_memfd >= 0) { - error_report("%s, KVM doesn't support KVM_CAP_USER_MEMORY2," - " which is required by guest memfd!", __func__); - exit(1); - } - mem.slot = slot->slot | (kml->as_id << 16); mem.guest_phys_addr = slot->start_addr; mem.userspace_addr = (unsigned long)slot->ram; @@ -309,7 +298,7 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot, boo * value. This is needed based on KVM commit 75d61fbc. */ mem.memory_size = 0; - if (cap_user_memory2) { + if (kvm_guest_memfd_supported) { ret = kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION2, &mem); } else { ret = kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem); @@ -319,7 +308,7 @@ static int kvm_set_user_memory_region(KVMMemoryListener *kml, KVMSlot *slot, boo } } mem.memory_size = slot->memory_size; - if (cap_user_memory2) { + if (kvm_guest_memfd_supported) { ret = kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION2, &mem); } else { ret = kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem); @@ -331,7 +320,7 @@ err: mem.userspace_addr, mem.guest_memfd, mem.guest_memfd_offset, ret); if (ret < 0) { - if (cap_user_memory2) { + if (kvm_guest_memfd_supported) { error_report("%s: KVM_SET_USER_MEMORY_REGION2 failed, slot=%d," " start=0x%" PRIx64 ", size=0x%" PRIx64 "," " flags=0x%" PRIx32 ", guest_memfd=%" PRId32 "," @@ -501,6 +490,7 @@ static int kvm_mem_flags(MemoryRegion *mr) flags |= KVM_MEM_READONLY; } if (memory_region_has_guest_memfd(mr)) { + assert(kvm_guest_memfd_supported); flags |= KVM_MEM_GUEST_MEMFD; } return flags;