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/ABI/testing/sysfs-secvar | 65 ++++++++++++++++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-secvar (limited to 'Documentation/ABI/testing/sysfs-secvar') diff --git a/Documentation/ABI/testing/sysfs-secvar b/Documentation/ABI/testing/sysfs-secvar new file mode 100644 index 000000000..c52a5fd15 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-secvar @@ -0,0 +1,65 @@ +What: /sys/firmware/secvar +Date: August 2019 +Contact: Nayna Jain +Description: This directory is created if the POWER firmware supports OS + secureboot, thereby secure variables. It exposes interface + for reading/writing the secure variables + +What: /sys/firmware/secvar/vars +Date: August 2019 +Contact: Nayna Jain +Description: This directory lists all the secure variables that are supported + by the firmware. + +What: /sys/firmware/secvar/format +Date: August 2019 +Contact: Nayna Jain +Description: A string indicating which backend is in use by the firmware. + This determines the format of the variable and the accepted + format of variable updates. + + On powernv/OPAL, this value is provided by the OPAL firmware + and is expected to be "ibm,edk2-compat-v1". + + On pseries/PLPKS, this is generated by the kernel based on the + version number in the SB_VERSION variable in the keystore. The + version numbering in the SB_VERSION variable starts from 1. The + format string takes the form "ibm,plpks-sb-v" in the + case of dynamic key management mode. If the SB_VERSION variable + does not exist (or there is an error while reading it), it takes + the form "ibm,plpks-sb-v0", indicating that the key management + mode is static. + +What: /sys/firmware/secvar/vars/ +Date: August 2019 +Contact: Nayna Jain +Description: Each secure variable is represented as a directory named as + . The variable name is unique and is in ASCII + representation. The data and size can be determined by reading + their respective attribute files. + + Only secvars relevant to the key management mode are exposed. + Only in the dynamic key management mode should the user have + access (read and write) to the secure boot secvars db, dbx, + grubdb, grubdbx, and sbat. These secvars are not consumed in the + static key management mode. PK, trustedcadb and moduledb are the + secvars common to both static and dynamic key management modes. + +What: /sys/firmware/secvar/vars//size +Date: August 2019 +Contact: Nayna Jain +Description: An integer representation of the size of the content of the + variable. In other words, it represents the size of the data. + +What: /sys/firmware/secvar/vars//data +Date: August 2019 +Contact: Nayna Jain +Description: A read-only file containing the value of the variable. The size + of the file represents the maximum size of the variable data. + +What: /sys/firmware/secvar/vars//update +Date: August 2019 +Contact: Nayna Jain +Description: A write-only file that is used to submit the new value for the + variable. The size of the file represents the maximum size of + the variable data that can be written. -- cgit v1.3.1