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 --- .../tools/check-fpatchable-function-entry.sh | 25 ++++++++++++++++++++++ 1 file changed, 25 insertions(+) create mode 100755 arch/powerpc/tools/check-fpatchable-function-entry.sh (limited to 'arch/powerpc/tools/check-fpatchable-function-entry.sh') diff --git a/arch/powerpc/tools/check-fpatchable-function-entry.sh b/arch/powerpc/tools/check-fpatchable-function-entry.sh new file mode 100755 index 000000000..baed467a0 --- /dev/null +++ b/arch/powerpc/tools/check-fpatchable-function-entry.sh @@ -0,0 +1,25 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 + +set -e + +# To debug, uncomment the following line +# set -x + +# Output from -fpatchable-function-entry can only vary on ppc64 elfv2, so this +# should not be invoked for other targets. Therefore we can pass in -m64 and +# -mabi explicitly, to take care of toolchains defaulting to other targets. + +# Test whether the compile option -fpatchable-function-entry exists and +# generates appropriate code +echo "int func() { return 0; }" | \ + $* -m64 -mabi=elfv2 -S -x c -O2 -fpatchable-function-entry=2 - -o - 2> /dev/null | \ + grep -q "__patchable_function_entries" + +# Test whether nops are generated after the local entry point +echo "int x; int func() { return x; }" | \ + $* -m64 -mabi=elfv2 -S -x c -O2 -fpatchable-function-entry=2 - -o - 2> /dev/null | \ + awk 'BEGIN { RS = ";" } /\.localentry.*nop.*\n[[:space:]]*nop/ { print $0 }' | \ + grep -q "func:" + +exit 0 -- cgit v1.3.1