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Tsirkin" , Igor Mammedov , Arun Menon , Stefan Berger Subject: [PATCH v7 6/6] hw/tpm: Add support for VM migration with TPM CRB chunking Date: Wed, 6 May 2026 13:28:13 +0530 Message-ID: <20260506075813.120781-7-armenon@redhat.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260506075813.120781-1-armenon@redhat.com> References: <20260506075813.120781-1-armenon@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=armenon@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=-0.443, 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_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-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: qemu development 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: Arun Menon - Add subsection in VMState for TPM CRB with the newly introduced command and response buffer GByteArrays, along with a needed callback, so that newer QEMU only sends the buffers if it is necessary. - Implement a migration blocker to prevent migration of the VM if the user manually enables chunking capability, cap-chunk, but the machine type does not support it, using a new hw_compat property called allow_chunk_migration. - Add a post_load_errp hook so that during a migration, the buffers are validated before destination VM is started. Signed-off-by: Arun Menon Reviewed-by: Stefan Berger --- hw/core/machine.c | 1 + hw/tpm/tpm_crb.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) diff --git a/hw/core/machine.c b/hw/core/machine.c index 4e0a93e231..30464b21ac 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -41,6 +41,7 @@ GlobalProperty hw_compat_11_0[] = { { "tpm-crb", "cap-chunk", "off" }, + { "tpm-crb", "x-allow-chunk-migration", "off" }, }; const size_t hw_compat_11_0_len = G_N_ELEMENTS(hw_compat_11_0); diff --git a/hw/tpm/tpm_crb.c b/hw/tpm/tpm_crb.c index f85df08185..54fa2042b5 100644 --- a/hw/tpm/tpm_crb.c +++ b/hw/tpm/tpm_crb.c @@ -24,6 +24,7 @@ #include "hw/pci/pci_ids.h" #include "hw/acpi/tpm.h" #include "migration/vmstate.h" +#include "migration/blocker.h" #include "system/tpm_backend.h" #include "system/tpm_util.h" #include "system/reset.h" @@ -50,6 +51,8 @@ struct CRBState { TPMPPI ppi; bool cap_chunk; + bool allow_chunk_migration; + Error *migration_blocker; }; typedef struct CRBState CRBState; @@ -349,18 +352,68 @@ static int tpm_crb_pre_save(void *opaque) return 0; } +static bool tpm_crb_chunk_needed(void *opaque) +{ + CRBState *s = opaque; + + if (!s->allow_chunk_migration) { + return false; + } + + return ((s->command_buffer && s->command_buffer->len > 0) || + (s->response_buffer && s->response_buffer->len > 0)); +} + +static bool tpm_crb_chunk_post_load(void *opaque, int version_id, Error **errp) +{ + CRBState *s = opaque; + + /* + * The external TPM emulator (example swtpm) determines the backend + * buffer capacity (s->be_buffer_size). This check ensures that if we + * migrate from a source with a PQC-enabled emulator that supports + * larger buffers to a destination with a non-PQC emulator, the + * migrated data does not exceed the destination's capacity. + */ + if (s->response_buffer->len > s->be_buffer_size || + s->command_buffer->len > s->be_buffer_size) { + error_setg(errp, "tpm-crb: Buffer sizes exceed backend capacity"); + return false; + } + return true; +} + +static const VMStateDescription vmstate_tpm_crb_chunk = { + .name = "tpm-crb/chunk", + .version_id = 0, + .needed = tpm_crb_chunk_needed, + .post_load_errp = tpm_crb_chunk_post_load, + .fields = (const VMStateField[]) { + VMSTATE_GBYTEARRAY(command_buffer, CRBState, 0), + VMSTATE_GBYTEARRAY(response_buffer, CRBState, 0), + VMSTATE_UINT32(response_offset, CRBState), + VMSTATE_END_OF_LIST() + } +}; + static const VMStateDescription vmstate_tpm_crb = { .name = "tpm-crb", .pre_save = tpm_crb_pre_save, .fields = (const VMStateField[]) { VMSTATE_UINT32_ARRAY(regs, CRBState, TPM_CRB_R_MAX), VMSTATE_END_OF_LIST(), + }, + .subsections = (const VMStateDescription * const []) { + &vmstate_tpm_crb_chunk, + NULL, } }; static const Property tpm_crb_properties[] = { DEFINE_PROP_TPMBE("tpmdev", CRBState, tpmbe), DEFINE_PROP_BOOL("cap-chunk", CRBState, cap_chunk, true), + DEFINE_PROP_BOOL("x-allow-chunk-migration", CRBState, + allow_chunk_migration, true), }; static void tpm_crb_reset(void *dev) @@ -415,6 +468,7 @@ static void tpm_crb_reset(void *dev) static void tpm_crb_realize(DeviceState *dev, Error **errp) { CRBState *s = CRB(dev); + int ret; if (!tpm_find()) { error_setg(errp, "at most one TPM device is permitted"); @@ -424,6 +478,15 @@ static void tpm_crb_realize(DeviceState *dev, Error **errp) error_setg(errp, "'tpmdev' property is required"); return; } + if (s->cap_chunk && !s->allow_chunk_migration) { + error_setg(&s->migration_blocker, + "The tpm-crb device does not support chunk migration with " + "machine version less than 11.1"); + ret = migrate_add_blocker_normal(&s->migration_blocker, errp); + if (ret < 0) { + return; + } + } memory_region_init_io(&s->mmio, OBJECT(s), &tpm_crb_memory_ops, s, "tpm-crb-mmio", sizeof(s->regs)); @@ -454,6 +517,10 @@ static void tpm_crb_unrealize(DeviceState *dev) g_clear_pointer(&s->command_buffer, g_byte_array_unref); g_clear_pointer(&s->response_buffer, g_byte_array_unref); + + if (s->migration_blocker) { + migrate_del_blocker(&s->migration_blocker); + } } static void tpm_crb_class_init(ObjectClass *klass, const void *data) -- 2.54.0