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, 83 insertions, 0 deletions

diff --git a/include/memory/renesas-rpc-if.h b/include/memory/renesas-rpc-if.h
new file mode 100644
index 000000000..53663c4e5
--- /dev/null
+++ b/include/memory/renesas-rpc-if.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Renesas RPC-IF core driver
+ *
+ * Copyright (C) 2018~2019 Renesas Solutions Corp.
+ * Copyright (C) 2019 Macronix International Co., Ltd.
+ * Copyright (C) 2019-2020 Cogent Embedded, Inc.
+ */
+
+#ifndef __RENESAS_RPC_IF_H
+#define __RENESAS_RPC_IF_H
+
+#include <linux/pm_runtime.h>
+#include <linux/types.h>
+
+enum rpcif_data_dir {
+	RPCIF_NO_DATA,
+	RPCIF_DATA_IN,
+	RPCIF_DATA_OUT,
+};
+
+struct rpcif_op {
+	struct {
+		u8 buswidth;
+		u8 opcode;
+		bool ddr;
+	} cmd, ocmd;
+
+	struct {
+		u8 nbytes;
+		u8 buswidth;
+		bool ddr;
+		u64 val;
+	} addr;
+
+	struct {
+		u8 ncycles;
+		u8 buswidth;
+	} dummy;
+
+	struct {
+		u8 nbytes;
+		u8 buswidth;
+		bool ddr;
+		u32 val;
+	} option;
+
+	struct {
+		u8 buswidth;
+		unsigned int nbytes;
+		enum rpcif_data_dir dir;
+		bool ddr;
+		union {
+			void *in;
+			const void *out;
+		} buf;
+	} data;
+};
+
+enum rpcif_type {
+	RPCIF_RCAR_GEN3,
+	RPCIF_RCAR_GEN4,
+	RPCIF_RZ_G2L,
+	XSPI_RZ_G3E,
+};
+
+struct rpcif {
+	struct device *dev;
+	void __iomem *dirmap;
+	size_t size;
+	bool xspi;
+};
+
+int rpcif_sw_init(struct rpcif *rpc, struct device *dev);
+int rpcif_hw_init(struct device *dev, bool hyperflash);
+void rpcif_prepare(struct device *dev, const struct rpcif_op *op, u64 *offs,
+		   size_t *len);
+int rpcif_manual_xfer(struct device *dev);
+ssize_t rpcif_dirmap_read(struct device *dev, u64 offs, size_t len, void *buf);
+ssize_t xspi_dirmap_write(struct device *dev, u64 offs, size_t len,
+			  const void *buf);
+
+#endif // __RENESAS_RPC_IF_H