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-bus-cdx | 121 ++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-bus-cdx (limited to 'Documentation/ABI/testing/sysfs-bus-cdx') diff --git a/Documentation/ABI/testing/sysfs-bus-cdx b/Documentation/ABI/testing/sysfs-bus-cdx new file mode 100644 index 000000000..e84277531 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-bus-cdx @@ -0,0 +1,121 @@ +What: /sys/bus/cdx/rescan +Date: March 2023 +Contact: nipun.gupta@amd.com +Description: + Writing y/1/on to this file will cause rescan of the bus + and devices on the CDX bus. Any new devices are scanned and + added to the list of Linux devices and any devices removed are + also deleted from Linux. + + For example:: + + # echo 1 > /sys/bus/cdx/rescan + +What: /sys/bus/cdx/devices/.../vendor +Date: March 2023 +Contact: nipun.gupta@amd.com +Description: + Vendor ID for this CDX device, in hexadecimal. Vendor ID is + 16 bit identifier which is specific to the device manufacturer. + Combination of Vendor ID and Device ID identifies a device. + +What: /sys/bus/cdx/devices/.../device +Date: March 2023 +Contact: nipun.gupta@amd.com +Description: + Device ID for this CDX device, in hexadecimal. Device ID is + 16 bit identifier to identify a device type within the range + of a device manufacturer. + Combination of Vendor ID and Device ID identifies a device. + +What: /sys/bus/cdx/devices/.../subsystem_vendor +Date: July 2023 +Contact: puneet.gupta@amd.com +Description: + Subsystem Vendor ID for this CDX device, in hexadecimal. + Subsystem Vendor ID is 16 bit identifier specific to the + card manufacturer. + +What: /sys/bus/cdx/devices/.../subsystem_device +Date: July 2023 +Contact: puneet.gupta@amd.com +Description: + Subsystem Device ID for this CDX device, in hexadecimal + Subsystem Device ID is 16 bit identifier specific to the + card manufacturer. + +What: /sys/bus/cdx/devices/.../class +Date: July 2023 +Contact: puneet.gupta@amd.com +Description: + This file contains the class of the CDX device, in hexadecimal. + Class is 24 bit identifier specifies the functionality of the device. + +What: /sys/bus/cdx/devices/.../revision +Date: July 2023 +Contact: puneet.gupta@amd.com +Description: + This file contains the revision field of the CDX device, in hexadecimal. + Revision is 8 bit revision identifier of the device. + +What: /sys/bus/cdx/devices/.../enable +Date: October 2023 +Contact: abhijit.gangurde@amd.com +Description: + CDX bus should be disabled before updating the devices in FPGA. + Writing n/0/off will attempt to disable the CDX bus and. + writing y/1/on will attempt to enable the CDX bus. Reading this file + gives the current state of the bus, 1 for enabled and 0 for disabled. + + For example:: + + # echo 1 > /sys/bus/cdx/.../enable + +What: /sys/bus/cdx/devices/.../reset +Date: March 2023 +Contact: nipun.gupta@amd.com +Description: + Writing y/1/on to this file resets the CDX device or all devices + on the bus. On resetting the device, the corresponding driver is + notified twice, once before the device is being reset, and again + after the reset has been complete. + + For example:: + + # echo 1 > /sys/bus/cdx/.../reset + +What: /sys/bus/cdx/devices/.../remove +Date: March 2023 +Contact: tarak.reddy@amd.com +Description: + Writing y/1/on to this file removes the corresponding + device from the CDX bus. If the device is to be reconfigured + reconfigured in the Hardware, the device can be removed, so + that the device driver does not access the device while it is + being reconfigured. + + For example:: + + # echo 1 > /sys/bus/cdx/devices/.../remove + +What: /sys/bus/cdx/devices/.../resource +Date: July 2023 +Contact: puneet.gupta@amd.com +Description: + The resource binary file contains the content of the memory + regions. These files can be m'maped from userspace. + +What: /sys/bus/cdx/devices/.../modalias +Date: July 2023 +Contact: nipun.gupta@amd.com +Description: + This attribute indicates the CDX ID of the device. + That is in the format: + cdx:vXXXXdXXXXsvXXXXsdXXXXcXXXXXX, + where: + + - vXXXX contains the vendor ID; + - dXXXX contains the device ID; + - svXXXX contains the subsystem vendor ID; + - sdXXXX contains the subsystem device ID; + - cXXXXXX contains the device class. -- cgit v1.3.1