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/strcpy-700.S | 67 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) create mode 100644 arch/arc/lib/strcpy-700.S (limited to 'arch/arc/lib/strcpy-700.S') diff --git a/arch/arc/lib/strcpy-700.S b/arch/arc/lib/strcpy-700.S new file mode 100644 index 000000000..6e2294d13 --- /dev/null +++ b/arch/arc/lib/strcpy-700.S @@ -0,0 +1,67 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com) + */ + +/* If dst and src are 4 byte aligned, copy 8 bytes at a time. + If the src is 4, but not 8 byte aligned, we first read 4 bytes to get + it 8 byte aligned. Thus, we can do a little read-ahead, without + dereferencing a cache line that we should not touch. + Note that short and long instructions have been scheduled to avoid + branch stalls. + The beq_s to r3z could be made unaligned & long to avoid a stall + there, but the it is not likely to be taken often, and it + would also be likey to cost an unaligned mispredict at the next call. */ + +#include + +ENTRY_CFI(strcpy) + or r2,r0,r1 + bmsk_s r2,r2,1 + brne.d r2,0,charloop + mov_s r10,r0 + ld_s r3,[r1,0] + mov r8,0x01010101 + bbit0.d r1,2,loop_start + ror r12,r8 + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne r3z + mov_s r4,r3 + .balign 4 +loop: + ld.a r3,[r1,4] + st.ab r4,[r10,4] +loop_start: + ld.a r4,[r1,4] + sub r2,r3,r8 + bic_s r2,r2,r3 + tst_s r2,r12 + bne_s r3z + st.ab r3,[r10,4] + sub r2,r4,r8 + bic r2,r2,r4 + tst r2,r12 + beq loop + mov_s r3,r4 +#ifdef __LITTLE_ENDIAN__ +r3z: bmsk.f r1,r3,7 + lsr_s r3,r3,8 +#else +r3z: lsr.f r1,r3,24 + asl_s r3,r3,8 +#endif + bne.d r3z + stb.ab r1,[r10,1] + j_s [blink] + + .balign 4 +charloop: + ldb.ab r3,[r1,1] + + + brne.d r3,0,charloop + stb.ab r3,[r10,1] + j [blink] +END_CFI(strcpy) -- cgit v1.3.1