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 --- include/crypto/internal/simd.h | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 include/crypto/internal/simd.h (limited to 'include/crypto/internal/simd.h') diff --git a/include/crypto/internal/simd.h b/include/crypto/internal/simd.h new file mode 100644 index 000000000..f5e5d7b63 --- /dev/null +++ b/include/crypto/internal/simd.h @@ -0,0 +1,40 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Shared crypto simd helpers + */ + +#ifndef _CRYPTO_INTERNAL_SIMD_H +#define _CRYPTO_INTERNAL_SIMD_H + +#include +#include +#include + +struct simd_aead_alg; +struct aead_alg; + +int simd_register_aeads_compat(struct aead_alg *algs, int count, + struct simd_aead_alg **simd_algs); + +void simd_unregister_aeads(struct aead_alg *algs, int count, + struct simd_aead_alg **simd_algs); + +/* + * crypto_simd_usable() - is it allowed at this time to use SIMD instructions or + * access the SIMD register file? + * + * This delegates to may_use_simd(), except that this also returns false if SIMD + * in crypto code has been temporarily disabled on this CPU by the crypto + * self-tests, in order to test the no-SIMD fallback code. This override is + * currently limited to configurations where the "full" self-tests are enabled, + * because it might be a bit too invasive to be part of the "fast" self-tests. + */ +#ifdef CONFIG_CRYPTO_SELFTESTS_FULL +DECLARE_PER_CPU(bool, crypto_simd_disabled_for_test); +#define crypto_simd_usable() \ + (may_use_simd() && !this_cpu_read(crypto_simd_disabled_for_test)) +#else +#define crypto_simd_usable() may_use_simd() +#endif + +#endif /* _CRYPTO_INTERNAL_SIMD_H */ -- cgit v1.3.1