From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration Manually perform cache maintenance on the source VM during intra-host migration to ensure no stale data is left in CPU caches after the VM is destroyed. Because the source VM is "converted" to a non-SEV VM, KVM's memory reclaim flows won't trigger cache maintenance, e.g. when all guest memory is reclaimed in response to detaching from the mmu_notifier. Note, relying on the destination VM to do cache maintenance isn't an option as KVM doesn't require identical guest memory configurations, i.e. the source VM may have access to memory that the destination VM does not. Enforcing equivalent memory configurations is infeasible, as it would require a *deep* comparison of memslots, e.g. to verify that not only are the memslot identical, but what the memslots point at is also identical. Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Cc: stable@vger.kernel.org Reported-by: Stefan Teodorescu Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- Documentation/driver-api/issei/index.rst | 16 ++++ Documentation/driver-api/issei/issei.rst | 135 +++++++++++++++++++++++++++++++ 2 files changed, 151 insertions(+) create mode 100644 Documentation/driver-api/issei/index.rst create mode 100644 Documentation/driver-api/issei/issei.rst (limited to 'Documentation/driver-api/issei') diff --git a/Documentation/driver-api/issei/index.rst b/Documentation/driver-api/issei/index.rst new file mode 100644 index 000000000..604267463 --- /dev/null +++ b/Documentation/driver-api/issei/index.rst @@ -0,0 +1,16 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. include:: + +========================================================= +The Intel Silicon Security Engine Interface (Intel SSEI) +========================================================= + +**Copyright** |copy| 2026 Intel Corporation + + +.. toctree:: + :caption: Table of Contents + :maxdepth: 3 + + issei diff --git a/Documentation/driver-api/issei/issei.rst b/Documentation/driver-api/issei/issei.rst new file mode 100644 index 000000000..a5e99e92e --- /dev/null +++ b/Documentation/driver-api/issei/issei.rst @@ -0,0 +1,135 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Introduction +============ + +The Intel Silicon Security Engine (Intel SSE) is an isolated and +protected computing resource (Co-processor) residing inside +Intel client chipsets released in 2024 (Lunar Lake) or later. +The Intel SSE provide security support and platform boot orchestration. +The actual feature set depends on the Intel chipset SKU. + +The Intel Silicon Security Engine Interface (Intel SSEI) +is the interface between the Host and Intel SSE. +This interface is exposed to the host as one or more PCI devices. +The Intel SSEI Driver is in charge of the communication channel between +a host application and the Intel SSE features. + +Each Intel SSE feature, or Intel SSE Client is addressed by a unique UUID and +each client has its own protocol. The protocol is message-based with a +header and payload up to maximal number of bytes advertised by the client, +upon connection. + +Intel SSEI Driver +================= + +The driver exposes a character device with device nodes /dev/isseiX. + +An application maintains communication with an Intel SSE feature while +/dev/isseiX is open. The binding to a specific feature is performed by calling +:c:macro:`IOCTL_ISSEI_CONNECT_CLIENT`, which passes the desired UUID. +The number of instances of an Intel SSE feature that can be opened +at the same time is limited to single instance. + +The driver is transparent to data that are passed between firmware feature +and host application. + +Because some of the Intel SSE features can change the system +configuration, the driver by default allows only a privileged +user to access it. + +The connection termination is performed by calling +:c:macro:`IOCTL_ISSEI_DISCONNECT_CLIENT`. + +The session is terminated calling :c:expr:`close(fd)`. + +A code snippet for an application communicating with SPDM client: + +.. code-block:: C + + struct issei_connect_client_data data = {.in_client_uuid = + {0xe8, 0x51, 0x49, 0xdf, 0x94, 0x47, 0x4C, + 0x9A, 0x83, 0x67, 0xC4, 0xE3, 0x34, 0x64, 0xF1, 0xB4}}; + __u8 req_data[] = {0x10, 0x84, 0x00, 0x00}; /* SPDM Get Version */ + size_t req_data_len = sizeof(req_data); + __u8 res_data[256]; + size_t res_data_len = sizeof(res_data); + int fd = open("/dev/issei0", O_RDWR); + + ioctl(fd, IOCTL_ISSEI_CONNECT_CLIENT, &data); + + printf("Ver=%d, MaxLen=%u, Flags=0x%08X\n", + data.out_client_properties.protocol_version, + data.out_client_properties.max_msg_length, + data.out_client_properties.flags); + + [...] + + write(fd, req_data, req_data_len); + + [...] + + read(fd, res_data, res_data_len); + + printf("SPDM version count %u, version[0]=%02X%02X\n", + res_data[5], res_data[6], res_data[7]); + + [...] + + ioctl(fd, IOCTL_ISSEI_DISCONNECT_CLIENT, &data); + + [...] + + close(fd); + + +User space API ioctl +==================== + +The Intel SSEI Driver supports the following ioctl commands: + +IOCTL_ISSEI_CONNECT_CLIENT +-------------------------- +Connect to firmware Feature/Client. + +.. code-block:: none + + Usage: + + struct issei_connect_client_data client_data; + + ioctl(fd, IOCTL_ISSEI_CONNECT_CLIENT, &client_data); + + struct issei_connect_client_data - contain the following + Inputs: + in_client_uuid - UUID of the FW Feature that needs to connect to. + Outputs: + out_client_properties - Client Properties: MTU, Protocol Version and Flags. + + Error returns: + ENOTTY No such client (i.e. wrong UUID) or connection is not allowed. + EINVAL Wrong IOCTL Number + ENODEV Device or Connection is not initialized or ready. + ENOMEM Unable to allocate memory to client internal data. + EFAULT Fatal Error (e.g. Unable to access user input data) + EBUSY Connection Already Open + +:Note: + max_msg_length (MTU) in client properties describes the maximum + data that can be sent or received. (e.g. with MTU=2K, can send + requests up to bytes 2k and received responses up to 2k bytes). + +IOCTL_ISSEI_DISCONNECT_CLIENT +----------------------------- +Disconnect from firmware Feature/Client. + +.. code-block:: none + + Usage: + + ioctl(fd, IOCTL_ISSEI_DISCONNECT_CLIENT, NULL); + + Error returns: + EINVAL Wrong IOCTL Number + ENODEV Device or Connection is not initialized or ready. + ENOTCONN Feature/Client is not connected. -- cgit v1.3.1