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/arch/powerpc/boot/of.h b/arch/powerpc/boot/of.h
new file mode 100644
index 000000000..31b2f5dfd
--- /dev/null
+++ b/arch/powerpc/boot/of.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _PPC_BOOT_OF_H_
+#define _PPC_BOOT_OF_H_
+
+#include "swab.h"
+
+typedef void *phandle;
+typedef u32 ihandle;
+
+void of_init(void *promptr);
+int of_call_prom(const char *service, int nargs, int nret, ...);
+unsigned int of_claim(unsigned long virt, unsigned long size,
+	unsigned long align);
+void *of_vmlinux_alloc(unsigned long size);
+void of_exit(void);
+void *of_finddevice(const char *name);
+int of_getprop(const void *phandle, const char *name, void *buf,
+	       const int buflen);
+int of_setprop(const void *phandle, const char *name, const void *buf,
+	       const int buflen);
+
+/* Console functions */
+void of_console_init(void);
+
+typedef u16			__be16;
+typedef u32			__be32;
+typedef u64			__be64;
+
+#ifdef __LITTLE_ENDIAN__
+#define cpu_to_be16(x) swab16(x)
+#define be16_to_cpu(x) swab16(x)
+#define cpu_to_be32(x) swab32(x)
+#define be32_to_cpu(x) swab32(x)
+#define cpu_to_be64(x) swab64(x)
+#define be64_to_cpu(x) swab64(x)
+#else
+#define cpu_to_be16(x) (x)
+#define be16_to_cpu(x) (x)
+#define cpu_to_be32(x) (x)
+#define be32_to_cpu(x) (x)
+#define cpu_to_be64(x) (x)
+#define be64_to_cpu(x) (x)
+#endif
+
+#define PROM_ERROR (-1u)
+
+#endif /* _PPC_BOOT_OF_H_ */