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 --- arch/arc/lib/strlen.S | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 80 insertions(+) create mode 100644 arch/arc/lib/strlen.S (limited to 'arch/arc/lib/strlen.S') diff --git a/arch/arc/lib/strlen.S b/arch/arc/lib/strlen.S new file mode 100644 index 000000000..dae428ceb --- /dev/null +++ b/arch/arc/lib/strlen.S @@ -0,0 +1,80 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +#include + +ENTRY_CFI(strlen) + or r3,r0,7 + ld r2,[r3,-7] + ld.a r6,[r3,-3] + mov r4,0x01010101 + ; uses long immediate +#ifdef __LITTLE_ENDIAN__ + asl_s r1,r0,3 + btst_s r0,2 + asl r7,r4,r1 + ror r5,r4 + sub r1,r2,r7 + bic_s r1,r1,r2 + mov.eq r7,r4 + sub r12,r6,r7 + bic r12,r12,r6 + or.eq r12,r12,r1 + and r12,r12,r5 + brne r12,0,.Learly_end +#else /* BIG ENDIAN */ + ror r5,r4 + btst_s r0,2 + mov_s r1,31 + sub3 r7,r1,r0 + sub r1,r2,r4 + bic_s r1,r1,r2 + bmsk r1,r1,r7 + sub r12,r6,r4 + bic r12,r12,r6 + bmsk.ne r12,r12,r7 + or.eq r12,r12,r1 + and r12,r12,r5 + brne r12,0,.Learly_end +#endif /* ENDIAN */ + +.Loop: + ld_s r2,[r3,4] + ld.a r6,[r3,8] + ; stall for load result + sub r1,r2,r4 + bic_s r1,r1,r2 + sub r12,r6,r4 + bic r12,r12,r6 + or r12,r12,r1 + and r12,r12,r5 + breq r12,0,.Loop +.Lend: + and.f r1,r1,r5 + sub.ne r3,r3,4 + mov.eq r1,r12 +#ifdef __LITTLE_ENDIAN__ + sub_s r2,r1,1 + bic_s r2,r2,r1 + norm r1,r2 + sub_s r0,r0,3 + lsr_s r1,r1,3 + sub r0,r3,r0 + j_s.d [blink] + sub r0,r0,r1 +#else /* BIG ENDIAN */ + lsr_s r1,r1,7 + mov.eq r2,r6 + bic_s r1,r1,r2 + norm r1,r1 + sub r0,r3,r0 + lsr_s r1,r1,3 + j_s.d [blink] + add r0,r0,r1 +#endif /* ENDIAN */ +.Learly_end: + b.d .Lend + sub_s.ne r1,r1,r1 +END_CFI(strlen) -- cgit v1.3.1