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, 54 insertions, 0 deletions

diff --git a/include/soc/microchip/mpfs.h b/include/soc/microchip/mpfs.h
new file mode 100644
index 000000000..ec04c98a8
--- /dev/null
+++ b/include/soc/microchip/mpfs.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *
+ * Microchip PolarFire SoC (MPFS)
+ *
+ * Copyright (c) 2020 Microchip Corporation. All rights reserved.
+ *
+ * Author: Conor Dooley <conor.dooley@microchip.com>
+ *
+ */
+
+#ifndef __SOC_MPFS_H__
+#define __SOC_MPFS_H__
+
+#include <linux/types.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+
+struct mpfs_sys_controller;
+
+struct mpfs_mss_msg {
+	u8 cmd_opcode;
+	u16 cmd_data_size;
+	struct mpfs_mss_response *response;
+	u8 *cmd_data;
+	u16 mbox_offset;
+	u16 resp_offset;
+};
+
+struct mpfs_mss_response {
+	u32 resp_status;
+	u32 *resp_msg;
+	u16 resp_size;
+};
+
+#if IS_ENABLED(CONFIG_POLARFIRE_SOC_SYS_CTRL)
+
+int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, struct mpfs_mss_msg *msg);
+
+struct mpfs_sys_controller *mpfs_sys_controller_get(struct device *dev);
+
+struct mtd_info *mpfs_sys_controller_get_flash(struct mpfs_sys_controller *mpfs_client);
+
+#endif /* if IS_ENABLED(CONFIG_POLARFIRE_SOC_SYS_CTRL) */
+
+#if IS_ENABLED(CONFIG_MCHP_CLK_MPFS)
+#if IS_ENABLED(CONFIG_RESET_POLARFIRE_SOC)
+int mpfs_reset_controller_register(struct device *clk_dev, struct regmap *map);
+#else
+static inline int mpfs_reset_controller_register(struct device *clk_dev, void __iomem *base) { return 0; }
+#endif /* if IS_ENABLED(CONFIG_RESET_POLARFIRE_SOC) */
+#endif /* if IS_ENABLED(CONFIG_MCHP_CLK_MPFS) */
+
+#endif /* __SOC_MPFS_H__ */