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, 271 insertions, 0 deletions

diff --git a/drivers/acpi/acpica/nsparse.c b/drivers/acpi/acpica/nsparse.c
new file mode 100644
index 000000000..1e9c70c38
--- /dev/null
+++ b/drivers/acpi/acpica/nsparse.c
@@ -0,0 +1,271 @@
+// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
+/******************************************************************************
+ *
+ * Module Name: nsparse - namespace interface to AML parser
+ *
+ * Copyright (C) 2000 - 2026, Intel Corp.
+ *
+ *****************************************************************************/
+
+#include <acpi/acpi.h>
+#include "accommon.h"
+#include "acnamesp.h"
+#include "acparser.h"
+#include "acdispat.h"
+#include "actables.h"
+#include "acinterp.h"
+
+#define _COMPONENT          ACPI_NAMESPACE
+ACPI_MODULE_NAME("nsparse")
+
+/*******************************************************************************
+ *
+ * FUNCTION:    ns_execute_table
+ *
+ * PARAMETERS:  table_desc      - An ACPI table descriptor for table to parse
+ *              start_node      - Where to enter the table into the namespace
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Load ACPI/AML table by executing the entire table as a single
+ *              large control method.
+ *
+ * NOTE: The point of this is to execute any module-level code in-place
+ * as the table is parsed. Some AML code depends on this behavior.
+ *
+ * It is a run-time option at this time, but will eventually become
+ * the default.
+ *
+ * Note: This causes the table to only have a single-pass parse.
+ * However, this is compatible with other ACPI implementations.
+ *
+ ******************************************************************************/
+acpi_status
+acpi_ns_execute_table(u32 table_index, struct acpi_namespace_node *start_node)
+{
+	acpi_status status;
+	struct acpi_table_header *table;
+	acpi_owner_id owner_id;
+	struct acpi_evaluate_info *info = NULL;
+	u32 aml_length;
+	u8 *aml_start;
+	union acpi_operand_object *method_obj = NULL;
+
+	ACPI_FUNCTION_TRACE(ns_execute_table);
+
+	status = acpi_get_table_by_index(table_index, &table);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/* Table must consist of at least a complete header */
+
+	if (table->length < sizeof(struct acpi_table_header)) {
+		return_ACPI_STATUS(AE_BAD_HEADER);
+	}
+
+	aml_start = (u8 *)table + sizeof(struct acpi_table_header);
+	aml_length = table->length - sizeof(struct acpi_table_header);
+
+	status = acpi_tb_get_owner_id(table_index, &owner_id);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/* Create, initialize, and link a new temporary method object */
+
+	method_obj = acpi_ut_create_internal_object(ACPI_TYPE_METHOD);
+	if (!method_obj) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	/* Allocate the evaluation information block */
+
+	info = ACPI_ALLOCATE_ZEROED(sizeof(struct acpi_evaluate_info));
+	if (!info) {
+		status = AE_NO_MEMORY;
+		goto cleanup;
+	}
+
+	ACPI_DEBUG_PRINT_RAW((ACPI_DB_PARSE,
+			      "%s: Create table pseudo-method for [%4.4s] @%p, method %p\n",
+			      ACPI_GET_FUNCTION_NAME, table->signature, table,
+			      method_obj));
+
+	method_obj->method.aml_start = aml_start;
+	method_obj->method.aml_length = aml_length;
+	method_obj->method.owner_id = owner_id;
+	method_obj->method.info_flags |= ACPI_METHOD_MODULE_LEVEL;
+
+	info->pass_number = ACPI_IMODE_EXECUTE;
+	info->node = start_node;
+	info->obj_desc = method_obj;
+	info->node_flags = info->node->flags;
+	info->full_pathname = acpi_ns_get_normalized_pathname(info->node, TRUE);
+	if (!info->full_pathname) {
+		status = AE_NO_MEMORY;
+		goto cleanup;
+	}
+
+	/* Optional object evaluation log */
+
+	ACPI_DEBUG_PRINT_RAW((ACPI_DB_EVALUATION,
+			      "%-26s:  (Definition Block level)\n",
+			      "Module-level evaluation"));
+
+	status = acpi_ps_execute_table(info);
+
+	/* Optional object evaluation log */
+
+	ACPI_DEBUG_PRINT_RAW((ACPI_DB_EVALUATION,
+			      "%-26s:  (Definition Block level)\n",
+			      "Module-level complete"));
+
+cleanup:
+	if (info) {
+		ACPI_FREE(info->full_pathname);
+		info->full_pathname = NULL;
+	}
+	ACPI_FREE(info);
+	acpi_ut_remove_reference(method_obj);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    ns_one_complete_parse
+ *
+ * PARAMETERS:  pass_number             - 1 or 2
+ *              table_desc              - The table to be parsed.
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Perform one complete parse of an ACPI/AML table.
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ns_one_complete_parse(u32 pass_number,
+			   u32 table_index,
+			   struct acpi_namespace_node *start_node)
+{
+	union acpi_parse_object *parse_root;
+	acpi_status status;
+	u32 aml_length;
+	u8 *aml_start;
+	struct acpi_walk_state *walk_state;
+	struct acpi_table_header *table;
+	acpi_owner_id owner_id;
+
+	ACPI_FUNCTION_TRACE(ns_one_complete_parse);
+
+	status = acpi_get_table_by_index(table_index, &table);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/* Table must consist of at least a complete header */
+
+	if (table->length < sizeof(struct acpi_table_header)) {
+		return_ACPI_STATUS(AE_BAD_HEADER);
+	}
+
+	aml_start = (u8 *)table + sizeof(struct acpi_table_header);
+	aml_length = table->length - sizeof(struct acpi_table_header);
+
+	status = acpi_tb_get_owner_id(table_index, &owner_id);
+	if (ACPI_FAILURE(status)) {
+		return_ACPI_STATUS(status);
+	}
+
+	/* Create and init a Root Node */
+
+	parse_root = acpi_ps_create_scope_op(aml_start);
+	if (!parse_root) {
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	/* Create and initialize a new walk state */
+
+	walk_state = acpi_ds_create_walk_state(owner_id, NULL, NULL, NULL);
+	if (!walk_state) {
+		acpi_ps_free_op(parse_root);
+		return_ACPI_STATUS(AE_NO_MEMORY);
+	}
+
+	status = acpi_ds_init_aml_walk(walk_state, parse_root, NULL,
+				       aml_start, aml_length, NULL,
+				       (u8)pass_number);
+	if (ACPI_FAILURE(status)) {
+		acpi_ds_delete_walk_state(walk_state);
+		goto cleanup;
+	}
+
+	/* Found OSDT table, enable the namespace override feature */
+
+	if (ACPI_COMPARE_NAMESEG(table->signature, ACPI_SIG_OSDT) &&
+	    pass_number == ACPI_IMODE_LOAD_PASS1) {
+		walk_state->namespace_override = TRUE;
+	}
+
+	/* start_node is the default location to load the table */
+
+	if (start_node && start_node != acpi_gbl_root_node) {
+		status =
+		    acpi_ds_scope_stack_push(start_node, ACPI_TYPE_METHOD,
+					     walk_state);
+		if (ACPI_FAILURE(status)) {
+			acpi_ds_delete_walk_state(walk_state);
+			goto cleanup;
+		}
+	}
+
+	/* Parse the AML */
+
+	ACPI_DEBUG_PRINT((ACPI_DB_PARSE,
+			  "*PARSE* pass %u parse\n", pass_number));
+	acpi_ex_enter_interpreter();
+	status = acpi_ps_parse_aml(walk_state);
+	acpi_ex_exit_interpreter();
+
+cleanup:
+	acpi_ps_delete_parse_tree(parse_root);
+	return_ACPI_STATUS(status);
+}
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_ns_parse_table
+ *
+ * PARAMETERS:  table_desc      - An ACPI table descriptor for table to parse
+ *              start_node      - Where to enter the table into the namespace
+ *
+ * RETURN:      Status
+ *
+ * DESCRIPTION: Parse AML within an ACPI table and return a tree of ops
+ *
+ ******************************************************************************/
+
+acpi_status
+acpi_ns_parse_table(u32 table_index, struct acpi_namespace_node *start_node)
+{
+	acpi_status status;
+
+	ACPI_FUNCTION_TRACE(ns_parse_table);
+
+	/*
+	 * Executes the AML table as one large control method.
+	 * The point of this is to execute any module-level code in-place
+	 * as the table is parsed. Some AML code depends on this behavior.
+	 *
+	 * Note: This causes the table to only have a single-pass parse.
+	 * However, this is compatible with other ACPI implementations.
+	 */
+	ACPI_DEBUG_PRINT_RAW((ACPI_DB_PARSE,
+			      "%s: **** Start table execution pass\n",
+			      ACPI_GET_FUNCTION_NAME));
+
+	status = acpi_ns_execute_table(table_index, start_node);
+
+	return_ACPI_STATUS(status);
+}