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, 35 insertions, 0 deletions

diff --git a/include/net/eee.h b/include/net/eee.h
new file mode 100644
index 000000000..cfab1b8bc
--- /dev/null
+++ b/include/net/eee.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _EEE_H
+#define _EEE_H
+
+#include <linux/types.h>
+
+struct eee_config {
+	u32 tx_lpi_timer;
+	bool tx_lpi_enabled;
+	bool eee_enabled;
+};
+
+static inline bool eeecfg_mac_can_tx_lpi(const struct eee_config *eeecfg)
+{
+	/* eee_enabled is the master on/off */
+	return eeecfg->eee_enabled && eeecfg->tx_lpi_enabled;
+}
+
+static inline void eeecfg_to_eee(struct ethtool_keee *eee,
+				 const struct eee_config *eeecfg)
+{
+	eee->tx_lpi_timer = eeecfg->tx_lpi_timer;
+	eee->tx_lpi_enabled = eeecfg->tx_lpi_enabled;
+	eee->eee_enabled = eeecfg->eee_enabled;
+}
+
+static inline void eee_to_eeecfg(struct eee_config *eeecfg,
+				 const struct ethtool_keee *eee)
+{
+	eeecfg->tx_lpi_timer = eee->tx_lpi_timer;
+	eeecfg->tx_lpi_enabled = eee->tx_lpi_enabled;
+	eeecfg->eee_enabled = eee->eee_enabled;
+}
+
+#endif