KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

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 <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 47 insertions, 0 deletions

diff --git a/include/asm-generic/int-ll64.h b/include/asm-generic/int-ll64.h
new file mode 100644
index 000000000..a248545f1
--- /dev/null
+++ b/include/asm-generic/int-ll64.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * asm-generic/int-ll64.h
+ *
+ * Integer declarations for architectures which use "long long"
+ * for 64-bit types.
+ */
+#ifndef _ASM_GENERIC_INT_LL64_H
+#define _ASM_GENERIC_INT_LL64_H
+
+#include <uapi/asm-generic/int-ll64.h>
+
+
+#ifndef __ASSEMBLY__
+
+typedef __s8  s8;
+typedef __u8  u8;
+typedef __s16 s16;
+typedef __u16 u16;
+typedef __s32 s32;
+typedef __u32 u32;
+typedef __s64 s64;
+typedef __u64 u64;
+
+#define S8_C(x)  x
+#define U8_C(x)  x ## U
+#define S16_C(x) x
+#define U16_C(x) x ## U
+#define S32_C(x) x
+#define U32_C(x) x ## U
+#define S64_C(x) x ## LL
+#define U64_C(x) x ## ULL
+
+#else /* __ASSEMBLY__ */
+
+#define S8_C(x)  x
+#define U8_C(x)  x
+#define S16_C(x) x
+#define U16_C(x) x
+#define S32_C(x) x
+#define U32_C(x) x
+#define S64_C(x) x
+#define U64_C(x) x
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_GENERIC_INT_LL64_H */