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/sound/hda/controllers/intel.h b/sound/hda/controllers/intel.h
new file mode 100644
index 000000000..4efb3b0fc
--- /dev/null
+++ b/sound/hda/controllers/intel.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ */
+#ifndef __SOUND_HDA_INTEL_H
+#define __SOUND_HDA_INTEL_H
+
+#include "hda_controller.h"
+
+struct hda_intel {
+	struct azx chip;
+
+	/* sync probing */
+	struct completion probe_wait;
+	struct delayed_work probe_work;
+
+	/* card list (for power_save trigger) */
+	struct list_head list;
+
+	/* extra flags */
+	unsigned int irq_pending_warned:1;
+	unsigned int probe_continued:1;
+	unsigned int runtime_pm_disabled:1;
+
+	/* vga_switcheroo setup */
+	unsigned int use_vga_switcheroo:1;
+	unsigned int vga_switcheroo_registered:1;
+	unsigned int init_failed:1; /* delayed init failed */
+	unsigned int freed:1; /* resources already released */
+
+	bool need_i915_power:1; /* the hda controller needs i915 power */
+
+	int probe_retry;	/* being probe-retry */
+};
+
+struct hda_intel_stream {
+	struct azx_dev azx_dev;
+
+	/* for pending irqs */
+	struct hda_intel *hda;
+	struct work_struct irq_pending_work;
+	bool irq_pending;
+};
+
+#define azx_dev_to_istream(azx_dev) \
+	container_of(azx_dev, struct hda_intel_stream, azx_dev)
+
+#endif