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/microblaze/lib/memset.c | 94 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 arch/microblaze/lib/memset.c (limited to 'arch/microblaze/lib/memset.c') diff --git a/arch/microblaze/lib/memset.c b/arch/microblaze/lib/memset.c new file mode 100644 index 000000000..7c2352d56 --- /dev/null +++ b/arch/microblaze/lib/memset.c @@ -0,0 +1,94 @@ +/* + * Copyright (C) 2008-2009 Michal Simek + * Copyright (C) 2008-2009 PetaLogix + * Copyright (C) 2007 John Williams + * + * Reasonably optimised generic C-code for memset on Microblaze + * This is generic C code to do efficient, alignment-aware memcpy. + * + * It is based on demo code originally Copyright 2001 by Intel Corp, taken from + * http://www.embedded.com/showArticle.jhtml?articleID=19205567 + * + * Attempts were made, unsuccessfully, to contact the original + * author of this code (Michael Morrow, Intel). Below is the original + * copyright notice. + * + * This software has been developed by Intel Corporation. + * Intel specifically disclaims all warranties, express or + * implied, and all liability, including consequential and + * other indirect damages, for the use of this program, including + * liability for infringement of any proprietary rights, + * and including the warranties of merchantability and fitness + * for a particular purpose. Intel does not assume any + * responsibility for and errors which may appear in this program + * not any responsibility to update it. + */ + +#include +#include +#include +#include +#include + +#ifdef CONFIG_OPT_LIB_FUNCTION +void *memset(void *v_src, int c, __kernel_size_t n) +{ + char *src = v_src; + uint32_t *i_src; + uint32_t w32 = 0; + + /* Truncate c to 8 bits */ + c = (c & 0xFF); + + if (unlikely(c)) { + /* Make a repeating word out of it */ + w32 = c; + w32 |= w32 << 8; + w32 |= w32 << 16; + } + + if (likely(n >= 4)) { + /* Align the destination to a word boundary */ + /* This is done in an endian independent manner */ + switch ((unsigned) src & 3) { + case 1: + *src++ = c; + --n; + fallthrough; + case 2: + *src++ = c; + --n; + fallthrough; + case 3: + *src++ = c; + --n; + } + + i_src = (void *)src; + + /* Do as many full-word copies as we can */ + for (; n >= 4; n -= 4) + *i_src++ = w32; + + src = (void *)i_src; + } + + /* Simple, byte oriented memset or the rest of count. */ + switch (n) { + case 3: + *src++ = c; + fallthrough; + case 2: + *src++ = c; + fallthrough; + case 1: + *src++ = c; + break; + default: + break; + } + + return v_src; +} +EXPORT_SYMBOL(memset); +#endif /* CONFIG_OPT_LIB_FUNCTION */ -- cgit v1.3.1