{"id":2197711,"url":"http://patchwork.ozlabs.org/api/1.0/patches/2197711/?format=json","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/1.0/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20260218114233.266178-6-anisinha@redhat.com>","date":"2026-02-18T11:41:58","name":"[v5,05/34] accel/kvm: add changes required to support KVM VM file descriptor change","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"c9203e9fc75bdac91cd8d9d170f2ce6a22f02c48","submitter":{"id":86030,"url":"http://patchwork.ozlabs.org/api/1.0/people/86030/?format=json","name":"Ani Sinha","email":"anisinha@redhat.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260218114233.266178-6-anisinha@redhat.com/mbox/","series":[{"id":492541,"url":"http://patchwork.ozlabs.org/api/1.0/series/492541/?format=json","date":"2026-02-18T11:41:56","name":"Introduce support for confidential guest reset (x86)","version":5,"mbox":"http://patchwork.ozlabs.org/series/492541/mbox/"}],"check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2197711/checks/","tags":{},"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=mimecast20190719 header.b=Cnnm872S;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=redhat.com header.i=@redhat.com header.a=rsa-sha256\n header.s=google header.b=O/CK4/ZB;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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KVM VM file descriptor can change as a part of confidential guest reset\nmechanism. A new function api kvm_arch_on_vmfd_change() per\narchitecture platform is added in order to implement architecture specific\nchanges required to support it. A subsequent patch will add x86 specific\nimplementation for kvm_arch_on_vmfd_change() as currently only x86 supports\nconfidential guest reset.\n\nSigned-off-by: Ani Sinha \n---\n MAINTAINERS | 6 ++++\n accel/kvm/kvm-all.c | 80 ++++++++++++++++++++++++++++++++++++++++--\n accel/kvm/trace-events | 1 +\n include/system/kvm.h | 3 ++\n stubs/kvm.c | 22 ++++++++++++\n stubs/meson.build | 1 +\n target/i386/kvm/kvm.c | 10 ++++++\n 7 files changed, 120 insertions(+), 3 deletions(-)\n create mode 100644 stubs/kvm.c","diff":"diff --git a/MAINTAINERS b/MAINTAINERS\nindex d3aa6d6732..b0eb77c08f 100644\n--- a/MAINTAINERS\n+++ b/MAINTAINERS\n@@ -152,6 +152,12 @@ F: tools/i386/\n F: tests/functional/i386/\n F: tests/functional/x86_64/\n \n+X86 VM file descriptor change on reset test\n+M: Ani Sinha \n+M: Paolo Bonzini \n+S: Maintained\n+F: stubs/kvm.c\n+\n Guest CPU cores (TCG)\n ---------------------\n Overall TCG CPUs\ndiff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c\nindex 0d8b0c4347..14729666a0 100644\n--- a/accel/kvm/kvm-all.c\n+++ b/accel/kvm/kvm-all.c\n@@ -2415,11 +2415,9 @@ void kvm_irqchip_set_qemuirq_gsi(KVMState *s, qemu_irq irq, int gsi)\n g_hash_table_insert(s->gsimap, irq, GINT_TO_POINTER(gsi));\n }\n \n-static void kvm_irqchip_create(KVMState *s)\n+static void do_kvm_irqchip_create(KVMState *s)\n {\n int ret;\n-\n- assert(s->kernel_irqchip_split != ON_OFF_AUTO_AUTO);\n if (kvm_check_extension(s, KVM_CAP_IRQCHIP)) {\n ;\n } else if (kvm_check_extension(s, KVM_CAP_S390_IRQCHIP)) {\n@@ -2452,7 +2450,13 @@ static void kvm_irqchip_create(KVMState *s)\n fprintf(stderr, \"Create kernel irqchip failed: %s\\n\", strerror(-ret));\n exit(1);\n }\n+}\n \n+static void kvm_irqchip_create(KVMState *s)\n+{\n+ assert(s->kernel_irqchip_split != ON_OFF_AUTO_AUTO);\n+\n+ do_kvm_irqchip_create(s);\n kvm_kernel_irqchip = true;\n /* If we have an in-kernel IRQ chip then we must have asynchronous\n * interrupt delivery (though the reverse is not necessarily true)\n@@ -2607,6 +2611,75 @@ static int kvm_setup_dirty_ring(KVMState *s)\n return 0;\n }\n \n+static int kvm_reset_vmfd(MachineState *ms)\n+{\n+ KVMState *s;\n+ KVMMemoryListener *kml;\n+ int ret = 0, type;\n+ Error *err = NULL;\n+\n+ /*\n+ * bail if the current architecture does not support VM file\n+ * descriptor change.\n+ */\n+ if (!kvm_arch_supports_vmfd_change()) {\n+ error_report(\"This target architecture does not support KVM VM \"\n+ \"file descriptor change.\");\n+ return -EOPNOTSUPP;\n+ }\n+\n+ s = KVM_STATE(ms->accelerator);\n+ kml = &s->memory_listener;\n+\n+ memory_listener_unregister(&kml->listener);\n+ memory_listener_unregister(&kvm_io_listener);\n+\n+ if (s->vmfd >= 0) {\n+ close(s->vmfd);\n+ }\n+\n+ type = find_kvm_machine_type(ms);\n+ if (type < 0) {\n+ return -EINVAL;\n+ }\n+\n+ ret = do_kvm_create_vm(s, type);\n+ if (ret < 0) {\n+ return ret;\n+ }\n+\n+ s->vmfd = ret;\n+\n+ kvm_setup_dirty_ring(s);\n+\n+ /* rebind memory to new vm fd */\n+ ret = ram_block_rebind(&err);\n+ if (ret < 0) {\n+ return ret;\n+ }\n+ assert(!err);\n+\n+ ret = kvm_arch_on_vmfd_change(ms, s);\n+ if (ret < 0) {\n+ return ret;\n+ }\n+\n+ if (s->kernel_irqchip_allowed) {\n+ do_kvm_irqchip_create(s);\n+ }\n+\n+ /* these can be only called after ram_block_rebind() */\n+ memory_listener_register(&kml->listener, &address_space_memory);\n+ memory_listener_register(&kvm_io_listener, &address_space_io);\n+\n+ /*\n+ * kvm fd has changed. Commit the irq routes to KVM once more.\n+ */\n+ kvm_irqchip_commit_routes(s);\n+ trace_kvm_reset_vmfd();\n+ return ret;\n+}\n+\n static int kvm_init(AccelState *as, MachineState *ms)\n {\n MachineClass *mc = MACHINE_GET_CLASS(ms);\n@@ -4015,6 +4088,7 @@ static void kvm_accel_class_init(ObjectClass *oc, const void *data)\n AccelClass *ac = ACCEL_CLASS(oc);\n ac->name = \"KVM\";\n ac->init_machine = kvm_init;\n+ ac->rebuild_guest = kvm_reset_vmfd;\n ac->has_memory = kvm_accel_has_memory;\n ac->allowed = &kvm_allowed;\n ac->gdbstub_supported_sstep_flags = kvm_gdbstub_sstep_flags;\ndiff --git a/accel/kvm/trace-events b/accel/kvm/trace-events\nindex e43d18a869..e4beda0148 100644\n--- a/accel/kvm/trace-events\n+++ b/accel/kvm/trace-events\n@@ -14,6 +14,7 @@ kvm_destroy_vcpu(int cpu_index, unsigned long arch_cpu_id) \"index: %d id: %lu\"\n kvm_park_vcpu(int cpu_index, unsigned long arch_cpu_id) \"index: %d id: %lu\"\n kvm_unpark_vcpu(unsigned long arch_cpu_id, const char *msg) \"id: %lu %s\"\n kvm_irqchip_commit_routes(void) \"\"\n+kvm_reset_vmfd(void) \"\"\n kvm_irqchip_add_msi_route(char *name, int vector, int virq) \"dev %s vector %d virq %d\"\n kvm_irqchip_update_msi_route(int virq) \"Updating MSI route virq=%d\"\n kvm_irqchip_release_virq(int virq) \"virq %d\"\ndiff --git a/include/system/kvm.h b/include/system/kvm.h\nindex 8f9eecf044..5fc7251fd9 100644\n--- a/include/system/kvm.h\n+++ b/include/system/kvm.h\n@@ -456,6 +456,9 @@ int kvm_physical_memory_addr_from_host(KVMState *s, void *ram_addr,\n \n #endif /* COMPILING_PER_TARGET */\n \n+bool kvm_arch_supports_vmfd_change(void);\n+int kvm_arch_on_vmfd_change(MachineState *ms, KVMState *s);\n+\n void kvm_cpu_synchronize_state(CPUState *cpu);\n \n void kvm_init_cpu_signals(CPUState *cpu);\ndiff --git a/stubs/kvm.c b/stubs/kvm.c\nnew file mode 100644\nindex 0000000000..2db61d89a7\n--- /dev/null\n+++ b/stubs/kvm.c\n@@ -0,0 +1,22 @@\n+/*\n+ * kvm target arch specific stubs\n+ *\n+ * Copyright (c) 2026 Red Hat, Inc.\n+ *\n+ * Author:\n+ * Ani Sinha \n+ *\n+ * SPDX-License-Identifier: GPL-2.0-or-later\n+ */\n+#include \"qemu/osdep.h\"\n+#include \"system/kvm.h\"\n+\n+int kvm_arch_on_vmfd_change(MachineState *ms, KVMState *s)\n+{\n+ abort();\n+}\n+\n+bool kvm_arch_supports_vmfd_change(void)\n+{\n+ return false;\n+}\ndiff --git a/stubs/meson.build b/stubs/meson.build\nindex 8a07059500..6ae478bacc 100644\n--- a/stubs/meson.build\n+++ b/stubs/meson.build\n@@ -74,6 +74,7 @@ if have_system\n if igvm.found()\n stub_ss.add(files('igvm.c'))\n endif\n+ stub_ss.add(files('kvm.c'))\n stub_ss.add(files('target-get-monitor-def.c'))\n stub_ss.add(files('target-monitor-defs.c'))\n stub_ss.add(files('win32-kbd-hook.c'))\ndiff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c\nindex 6d823a7991..a4e18734b1 100644\n--- a/target/i386/kvm/kvm.c\n+++ b/target/i386/kvm/kvm.c\n@@ -3389,6 +3389,16 @@ static int kvm_vm_enable_energy_msrs(KVMState *s)\n return 0;\n }\n \n+int kvm_arch_on_vmfd_change(MachineState *ms, KVMState *s)\n+{\n+ abort();\n+}\n+\n+bool kvm_arch_supports_vmfd_change(void)\n+{\n+ return false;\n+}\n+\n int kvm_arch_init(MachineState *ms, KVMState *s)\n {\n int ret;\n","prefixes":["v5","05/34"]}