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-kernel-kexec-kdump | 61 ++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-kernel-kexec-kdump (limited to 'Documentation/ABI/testing/sysfs-kernel-kexec-kdump') diff --git a/Documentation/ABI/testing/sysfs-kernel-kexec-kdump b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump new file mode 100644 index 000000000..f59051b5d --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-kexec-kdump @@ -0,0 +1,61 @@ +What: /sys/kernel/kexec/* +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: + The /sys/kernel/kexec/* directory contains sysfs files + that provide information about the configuration status + of kexec and kdump. + +What: /sys/kernel/kexec/loaded +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates whether a new kernel image has been loaded + into memory using the kexec system call. It shows 1 if + a kexec image is present and ready to boot, or 0 if none + is loaded. +User: kexec tools, kdump service + +What: /sys/kernel/kexec/crash_loaded +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates whether a crash (kdump) kernel is currently + loaded into memory. It shows 1 if a crash kernel has been + successfully loaded for panic handling, or 0 if no crash + kernel is present. +User: Kexec tools, Kdump service + +What: /sys/kernel/kexec/crash_size +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read/write + Shows the amount of memory reserved for loading the crash + (kdump) kernel. It reports the size, in bytes, of the + crash kernel area defined by the crashkernel= parameter. + This interface also allows reducing the crashkernel + reservation by writing a smaller value, and the reclaimed + space is added back to the system RAM. +User: Kdump service + +What: /sys/kernel/kexec/crash_elfcorehdr_size +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Indicates the preferred size of the memory buffer for the + ELF core header used by the crash (kdump) kernel. It defines + how much space is needed to hold metadata about the crashed + system, including CPU and memory information. This information + is used by the user space utility kexec to support updating the + in-kernel kdump image during hotplug operations. +User: Kexec tools + +What: /sys/kernel/kexec/crash_cma_ranges +Date: Nov 2025 +Contact: kexec@lists.infradead.org +Description: read only + Provides information about the memory ranges reserved from + the Contiguous Memory Allocator (CMA) area that are allocated + to the crash (kdump) kernel. It lists the start and end physical + addresses of CMA regions assigned for crashkernel use. +User: kdump service -- cgit v1.3.1