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/alpha/lib/ev67-strcat.S | 56 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 arch/alpha/lib/ev67-strcat.S (limited to 'arch/alpha/lib/ev67-strcat.S') diff --git a/arch/alpha/lib/ev67-strcat.S b/arch/alpha/lib/ev67-strcat.S new file mode 100644 index 000000000..f8c7305b1 --- /dev/null +++ b/arch/alpha/lib/ev67-strcat.S @@ -0,0 +1,56 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * arch/alpha/lib/ev67-strcat.S + * 21264 version contributed by Rick Gorton + * + * Append a null-terminated string from SRC to DST. + * + * Much of the information about 21264 scheduling/coding comes from: + * Compiler Writer's Guide for the Alpha 21264 + * abbreviated as 'CWG' in other comments here + * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html + * Scheduling notation: + * E - either cluster + * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1 + * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1 + * Try not to change the actual algorithm if possible for consistency. + * Commentary: It seems bogus to walk the input string twice - once + * to determine the length, and then again while doing the copy. + * A significant (future) enhancement would be to only read the input + * string once. + */ + +#include + .text + + .align 4 + .globl strcat + .ent strcat +strcat: + .frame $30, 0, $26 + .prologue 0 + + mov $16, $0 # E : set up return value + /* Find the end of the string. */ + ldq_u $1, 0($16) # L : load first quadword (a0 may be misaligned) + lda $2, -1 # E : + insqh $2, $16, $2 # U : + + andnot $16, 7, $16 # E : + or $2, $1, $1 # E : + cmpbge $31, $1, $2 # E : bits set iff byte == 0 + bne $2, $found # U : + +$loop: ldq $1, 8($16) # L : + addq $16, 8, $16 # E : + cmpbge $31, $1, $2 # E : + beq $2, $loop # U : + +$found: cttz $2, $3 # U0 : + addq $16, $3, $16 # E : + /* Now do the append. */ + mov $26, $23 # E : + br __stxcpy # L0 : + + .end strcat + EXPORT_SYMBOL(strcat) -- cgit v1.3.1