From patchwork Tue Apr 23 15:09:43 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 13640263 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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C739EC10F1A for ; Tue, 23 Apr 2024 15:16:17 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rzHnb-0006yK-0I; Tue, 23 Apr 2024 11:11:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rzHnI-00057X-8B for qemu-devel@nongnu.org; Tue, 23 Apr 2024 11:10:52 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rzHnG-0000L6-7X for qemu-devel@nongnu.org; Tue, 23 Apr 2024 11:10:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1713885049; 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=6tUwxNFvDwg2j+J2ayrByxDVV2OoEExUkjc4qnuWI2Y=; b=OAA/EBrJLEHsPvejD8JbIAknIO9bpzmJphhYG6liZVwRiuZvxoelnG8ctJuL3pkvZPXuTR 3GemaGPDbekNV7H4FNcYDISd9WJrKJDDQmrm6daj3Dx8u4UhsOmyzAn5fmr1hVSUML2cKh obdAbcGwzRD3YODtIpoR8jQeobOBGAU= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-402-8E4S23jwMU-scPmni7FpVg-1; Tue, 23 Apr 2024 11:10:48 -0400 X-MC-Unique: 8E4S23jwMU-scPmni7FpVg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C2DDE1049881; Tue, 23 Apr 2024 15:10:47 +0000 (UTC) Received: from avogadro.lan (unknown [10.39.192.70]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1A08F203397E; Tue, 23 Apr 2024 15:10:46 +0000 (UTC) From: Paolo Bonzini To: qemu-devel@nongnu.org Cc: Chao Peng , Xiaoyao Li Subject: [PULL 55/63] kvm: handle KVM_EXIT_MEMORY_FAULT Date: Tue, 23 Apr 2024 17:09:43 +0200 Message-ID: <20240423150951.41600-56-pbonzini@redhat.com> In-Reply-To: <20240423150951.41600-1-pbonzini@redhat.com> References: <20240423150951.41600-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 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: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.67, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=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: 2.1.29 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 From: Chao Peng Upon an KVM_EXIT_MEMORY_FAULT exit, userspace needs to do the memory conversion on the RAMBlock to turn the memory into desired attribute, switching between private and shared. Currently only KVM_MEMORY_EXIT_FLAG_PRIVATE in flags is valid when KVM_EXIT_MEMORY_FAULT happens. Note, KVM_EXIT_MEMORY_FAULT makes sense only when the RAMBlock has guest_memfd memory backend. Note, KVM_EXIT_MEMORY_FAULT returns with -EFAULT, so special handling is added. When page is converted from shared to private, the original shared memory can be discarded via ram_block_discard_range(). Note, shared memory can be discarded only when it's not back'ed by hugetlb because hugetlb is supposed to be pre-allocated and no need for discarding. Signed-off-by: Chao Peng Co-developed-by: Xiaoyao Li Signed-off-by: Xiaoyao Li Message-ID: <20240320083945.991426-13-michael.roth@amd.com> Signed-off-by: Paolo Bonzini --- include/sysemu/kvm.h | 2 + accel/kvm/kvm-all.c | 98 +++++++++++++++++++++++++++++++++++++----- accel/kvm/trace-events | 2 + 3 files changed, 92 insertions(+), 10 deletions(-) diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h index 217f3fe17ba..47f9e8be1b3 100644 --- a/include/sysemu/kvm.h +++ b/include/sysemu/kvm.h @@ -542,4 +542,6 @@ int kvm_create_guest_memfd(uint64_t size, uint64_t flags, Error **errp); int kvm_set_memory_attributes_private(hwaddr start, uint64_t size); int kvm_set_memory_attributes_shared(hwaddr start, uint64_t size); +int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private); + #endif diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c index f49b2b95b54..9eef2c64003 100644 --- a/accel/kvm/kvm-all.c +++ b/accel/kvm/kvm-all.c @@ -2900,6 +2900,69 @@ static void kvm_eat_signals(CPUState *cpu) } while (sigismember(&chkset, SIG_IPI)); } +int kvm_convert_memory(hwaddr start, hwaddr size, bool to_private) +{ + MemoryRegionSection section; + ram_addr_t offset; + MemoryRegion *mr; + RAMBlock *rb; + void *addr; + int ret = -1; + + trace_kvm_convert_memory(start, size, to_private ? "shared_to_private" : "private_to_shared"); + + if (!QEMU_PTR_IS_ALIGNED(start, qemu_real_host_page_size()) || + !QEMU_PTR_IS_ALIGNED(size, qemu_real_host_page_size())) { + return -1; + } + + if (!size) { + return -1; + } + + section = memory_region_find(get_system_memory(), start, size); + mr = section.mr; + if (!mr) { + return -1; + } + + if (!memory_region_has_guest_memfd(mr)) { + error_report("Converting non guest_memfd backed memory region " + "(0x%"HWADDR_PRIx" ,+ 0x%"HWADDR_PRIx") to %s", + start, size, to_private ? "private" : "shared"); + goto out_unref; + } + + if (to_private) { + ret = kvm_set_memory_attributes_private(start, size); + } else { + ret = kvm_set_memory_attributes_shared(start, size); + } + if (ret) { + goto out_unref; + } + + addr = memory_region_get_ram_ptr(mr) + section.offset_within_region; + rb = qemu_ram_block_from_host(addr, false, &offset); + + if (to_private) { + if (rb->page_size != qemu_real_host_page_size()) { + /* + * shared memory is backed by hugetlb, which is supposed to be + * pre-allocated and doesn't need to be discarded + */ + goto out_unref; + } + ret = ram_block_discard_range(rb, offset, size); + } else { + ret = ram_block_discard_guest_memfd_range(rb, offset, size); + } + +out_unref: + memory_region_unref(mr); + return ret; +} + int kvm_cpu_exec(CPUState *cpu) { struct kvm_run *run = cpu->kvm_run; @@ -2967,18 +3030,20 @@ int kvm_cpu_exec(CPUState *cpu) ret = EXCP_INTERRUPT; break; } - fprintf(stderr, "error: kvm run failed %s\n", - strerror(-run_ret)); + if (!(run_ret == -EFAULT && run->exit_reason == KVM_EXIT_MEMORY_FAULT)) { + fprintf(stderr, "error: kvm run failed %s\n", + strerror(-run_ret)); #ifdef TARGET_PPC - if (run_ret == -EBUSY) { - fprintf(stderr, - "This is probably because your SMT is enabled.\n" - "VCPU can only run on primary threads with all " - "secondary threads offline.\n"); - } + if (run_ret == -EBUSY) { + fprintf(stderr, + "This is probably because your SMT is enabled.\n" + "VCPU can only run on primary threads with all " + "secondary threads offline.\n"); + } #endif - ret = -1; - break; + ret = -1; + break; + } } trace_kvm_run_exit(cpu->cpu_index, run->exit_reason); @@ -3061,6 +3126,19 @@ int kvm_cpu_exec(CPUState *cpu) break; } break; + case KVM_EXIT_MEMORY_FAULT: + trace_kvm_memory_fault(run->memory_fault.gpa, + run->memory_fault.size, + run->memory_fault.flags); + if (run->memory_fault.flags & ~KVM_MEMORY_EXIT_FLAG_PRIVATE) { + error_report("KVM_EXIT_MEMORY_FAULT: Unknown flag 0x%" PRIx64, + (uint64_t)run->memory_fault.flags); + ret = -1; + break; + } + ret = kvm_convert_memory(run->memory_fault.gpa, run->memory_fault.size, + run->memory_fault.flags & KVM_MEMORY_EXIT_FLAG_PRIVATE); + break; default: ret = kvm_arch_handle_exit(cpu, run); break; diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events index e8c52cb9e7a..681ccb667d6 100644 --- a/accel/kvm/trace-events +++ b/accel/kvm/trace-events @@ -31,3 +31,5 @@ kvm_cpu_exec(void) "" kvm_interrupt_exit_request(void) "" kvm_io_window_exit(void) "" kvm_run_exit_system_event(int cpu_index, uint32_t event_type) "cpu_index %d, system_even_type %"PRIu32 +kvm_convert_memory(uint64_t start, uint64_t size, const char *msg) "start 0x%" PRIx64 " size 0x%" PRIx64 " %s" +kvm_memory_fault(uint64_t start, uint64_t size, uint64_t flags) "start 0x%" PRIx64 " size 0x%" PRIx64 " flags 0x%" PRIx64