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Wed, 15 Jul 2026 13:21:34 -0700 (PDT) Date: Wed, 15 Jul 2026 14:21:31 -0600 From: Mathieu Poirier To: Gavin Shan Cc: berrange@redhat.com, kchamart@redhat.com, pierrick.bouvier@oss.qualcomm.com, peter.maydell@linaro.org, mst@redhat.com, cohuck@redhat.com, pbonzini@redhat.com, eblake@redhat.com, armbru@redhat.com, jpb@kernel.org, lorenzo.pieralisi@linaro.org, qemu-devel@nongnu.org, qemu-arm@nongnu.org, kvm@vger.kernel.org Subject: Re: [RFC v1 04/25] target/arm/kvm-rme: Add mechanic to initialize realms Message-ID: References: <20260707224306.1202330-1-mathieu.poirier@linaro.org> <20260707224306.1202330-5-mathieu.poirier@linaro.org> <4ffc3787-a53e-4889-b245-458de4463cb9@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4ffc3787-a53e-4889-b245-458de4463cb9@redhat.com> On Mon, Jul 13, 2026 at 03:34:20PM +1000, Gavin Shan wrote: > On 7/8/26 8:42 AM, Mathieu Poirier wrote: > > From: Jean-Philippe Brucker > > > > Initialise an @rme_guest object and install a handler to get notified > > when the Realm is ready to start. That way we can finish reading the > > Realm once we know everything is in place. > > > > Signed-off-by: Jean-Philippe Brucker > > Signed-off-by: Mathieu Poirier > > --- > > target/arm/kvm-rme.c | 50 +++++++++++++++++++++++++++++++++++++++++++ > > target/arm/kvm-stub.c | 5 +++++ > > target/arm/kvm.c | 7 +++++- > > target/arm/kvm_arm.h | 9 ++++++++ > > 4 files changed, 70 insertions(+), 1 deletion(-) > > > > diff --git a/target/arm/kvm-rme.c b/target/arm/kvm-rme.c > > index 42e1d1e7b859..b86b9d6a25cb 100644 > > --- a/target/arm/kvm-rme.c > > +++ b/target/arm/kvm-rme.c > > @@ -13,6 +13,7 @@ > > #include "kvm_arm.h" > > #include "migration/blocker.h" > > #include "qapi/error.h" > > +#include "qemu/error-report.h" > > #include "qom/object_interfaces.h" > > #include "system/confidential-guest-support.h" > > #include "system/kvm.h" > > @@ -29,14 +30,63 @@ OBJECT_DEFINE_SIMPLE_TYPE_WITH_INTERFACES(RmeGuest, rme_guest, RME_GUEST, > > CONFIDENTIAL_GUEST_SUPPORT, > > { TYPE_USER_CREATABLE }, { }) > > +static RmeGuest *rme_guest; > > + > > +static void rme_vm_state_change(void *opaque, bool running, RunState state) > > +{ > > + if (!running) { > > + return; > > + } > > + > > + kvm_mark_guest_state_protected(); > > This would be called in kvm_arm_rme_init(), why we can't call this to mark the > KVM state as protected in kvm_arm_rme_init() ? > One of the very last things happening in qemu_init() is a call to qmp_x_exit_preconfig(), which ultimately ends up calling qemu_system_reset(). If we mark the guest state as protected before qemu_system_reset() is called, as it would be the case if we move kvm_mark_guest_state_protected() to kvm_arm_rme_init(), general purposes and the program counter registers don't get pushed down to KVM, resulting in a failure to start the Realm. > > +} > > + > > static void rme_guest_class_init(ObjectClass *oc, const void *data) > > { > > } > > static void rme_guest_init(Object *obj) > > { > > + if (rme_guest) { > > + error_report("a single instance of RmeGuest is supported"); > > + exit(1); > > + } > > + rme_guest = RME_GUEST(obj); > > } > > static void rme_guest_finalize(Object *obj) > > { > > } > > + > > +int kvm_arm_rme_init(MachineState *ms, KVMState *s) > > +{ > > + static Error *rme_mig_blocker; > > + ConfidentialGuestSupport *cgs = ms->cgs; > > + > > + if (!rme_guest) { > > + return 0; > > + } > > + > > + if (!cgs) { > > + error_report("missing -machine confidential-guest-support parameter"); > > + return -EINVAL; > > + } > > + > > + if (!kvm_vm_check_extension(s, KVM_CAP_ARM_RMI)) { > > + error_report("KVM doesn't support Realms"); > > + return -ENODEV; > > + } > > + > > + error_setg(&rme_mig_blocker, "RME: migration is not implemented"); > > + migrate_add_blocker(&rme_mig_blocker, &error_fatal); > > + > > + /* > > + * The realm activation is done last, when the VM starts, after all images > > + * have been loaded and all vcpus finalized. > > + */ > > + qemu_add_vm_change_state_handler(rme_vm_state_change, NULL); > > + > > + cgs->require_guest_memfd = true; > > + cgs->ready = true; > > + return 0; > > +} > > diff --git a/target/arm/kvm-stub.c b/target/arm/kvm-stub.c > > index 88cbe8d85c41..eec1ca3dd2e5 100644 > > --- a/target/arm/kvm-stub.c > > +++ b/target/arm/kvm-stub.c > > @@ -119,3 +119,8 @@ char *kvm_print_register_name(uint64_t regidx) > > { > > g_assert_not_reached(); > > } > > + > > +int kvm_arm_rme_init(MachineState *ms, KVMState *s) > > +{ > > + g_assert_not_reached(); > > +} > > diff --git a/target/arm/kvm.c b/target/arm/kvm.c > > index ed99be7fd80c..28d5643d6779 100644 > > --- a/target/arm/kvm.c > > +++ b/target/arm/kvm.c > > @@ -660,7 +660,12 @@ int kvm_arch_init(MachineState *ms, KVMState *s) > > hw_breakpoints = g_array_sized_new(true, true, > > sizeof(HWBreakpoint), max_hw_bps); > > - return 0; > > + ret = kvm_arm_rme_init(ms, s); > > + if (ret) { > > + error_report("Failed to enable RME: %s", strerror(-ret)); > > + } > > + > > + return ret; > > } > > unsigned long kvm_arch_vcpu_id(CPUState *cpu) > > diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h > > index e7c40fb003e4..6d058b0e08a2 100644 > > --- a/target/arm/kvm_arm.h > > +++ b/target/arm/kvm_arm.h > > @@ -240,4 +240,13 @@ void arm_gic_cap_kvm_probe(GICCapability *v2, GICCapability *v3); > > */ > > char *kvm_print_register_name(uint64_t regidx); > > +/** > > + * kvm_arm_rme_init > > + * @ms: the machine state > > + * @s: State of KVM > > + * > > + * Prepare the machine to be a Realm, if the user enabled it. > > + */ > > +int kvm_arm_rme_init(MachineState *ms, KVMState *s); > > + > > #endif > > Thanks, > Gavin >