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bh=6tUwxNFvDwg2j+J2ayrByxDVV2OoEExUkjc4qnuWI2Y=; b=OAA/EBrJLEHsPvejD8JbIAknIO9bpzmJphhYG6liZVwRiuZvxoelnG8ctJuL3pkvZPXuTR 3GemaGPDbekNV7H4FNcYDISd9WJrKJDDQmrm6daj3Dx8u4UhsOmyzAn5fmr1hVSUML2cKh obdAbcGwzRD3YODtIpoR8jQeobOBGAU= X-MC-Unique: 8E4S23jwMU-scPmni7FpVg-1 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 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1713885379083100002 Content-Type: text/plain; charset="utf-8" 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 flag= s, Error **errp); int kvm_set_memory_attributes_private(hwaddr start, uint64_t size); int kvm_set_memory_attributes_shared(hwaddr start, uint64_t size); =20 +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)); } =20 +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 =3D -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 =3D memory_region_find(get_system_memory(), start, size); + mr =3D 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 =3D kvm_set_memory_attributes_private(start, size); + } else { + ret =3D kvm_set_memory_attributes_shared(start, size); + } + if (ret) { + goto out_unref; + } + + addr =3D memory_region_get_ram_ptr(mr) + section.offset_within_region; + rb =3D qemu_ram_block_from_host(addr, false, &offset); + + if (to_private) { + if (rb->page_size !=3D 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 =3D ram_block_discard_range(rb, offset, size); + } else { + ret =3D 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 =3D cpu->kvm_run; @@ -2967,18 +3030,20 @@ int kvm_cpu_exec(CPUState *cpu) ret =3D EXCP_INTERRUPT; break; } - fprintf(stderr, "error: kvm run failed %s\n", - strerror(-run_ret)); + if (!(run_ret =3D=3D -EFAULT && run->exit_reason =3D=3D KVM_EX= IT_MEMORY_FAULT)) { + fprintf(stderr, "error: kvm run failed %s\n", + strerror(-run_ret)); #ifdef TARGET_PPC - if (run_ret =3D=3D -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 =3D=3D -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 =3D -1; - break; + ret =3D -1; + break; + } } =20 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%" PRI= x64, + (uint64_t)run->memory_fault.flags); + ret =3D -1; + break; + } + ret =3D kvm_convert_memory(run->memory_fault.gpa, run->memory_= fault.size, + run->memory_fault.flags & KVM_MEMORY_= EXIT_FLAG_PRIVATE); + break; default: ret =3D 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 --=20 2.44.0